| Title of Invention | "IDENTIFICATION AND ENGINEERING OF ANTIBODIES WITH VARIANT FC REGIONS AND METHODS OF USING SAME" |
|---|---|
| Abstract | The present invention relates to molecules, particularly polypeptides, more particularly immunoglobulins (e.g., antibodies), comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcϝRIIIA and/or FcϝRIIA with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. The molecules of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcϝR is desired, e.g. , cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC. |
| Full Text | A I)rA1~TT F'- REGIONS AND METHODg OF USING fAME 1. FIELD OF THE INVENTION [0001] The present invention relates to molecules, particularly polypeptides, more particularly immunoglobulins (e.g., antibodies), comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds Fc'RIIIA and/or FcRIIA with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. The molecules of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcTR is desired, e.g., cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC. 2. BACKGROUND OF THE INVENTION 2.1 Fe RECEPTORS AND THEIR ROLES IN TILE IMMUNE SYSTEM [00021 The interaction of antibody-antigen complexes with cells of the immune system results in a wide array of responses, ranging from effector fimctions such as antibody-dependent cytotoxicity, mast cell degranulation, and phagocytosis to immunomodulatory signals such as regulating lymphocyte proliferation and antibody secretion. All these interactions are initiated through the binding of the Fc domain of antibodies or immune complexes to specialized cell surface receptors on hematopoietic cells. The diversity of cellular responses triggered by antibodies and immune complexes results from the structural heterogeneity of Fe receptors. Fc receptors share structurally related ilgand binding domains which presumably mediate intracellular signaling. [0003] The Fc receptors, members of the immunoglobulin gene superfamily of proteins, are surface glycoproteins that can bind the Fe portion of inimunoglobulin molecules. Each member of the family recognizes immunoglobulins of one or more isotypes through a recognition domain on the a chain of the Fe receptor. Fe receptors are defined by their specificity for inimunoglobulin subtypes. Fe receptors for IgG are referred to as FoyR, for IgE as FaR, and for IgA as FeaR. Different accessory cells bear Fe receptors for antibodies of different isotype, and the isotype of the antibody determines which accessory cells will be engaged in a given response (reviewed by Ravetch J.V. etal. 199 Lrk.mzw Reva Immuiol. 9: 457-92; Gerber J.S. et a?. 2001 Microbes and Infection, 3: 13 1-139; Billadeau D.D. eta!. 2002, The Journal of Clinical Investigation, 2(109): 161- 1681; Ravetch J.V. eta?. 2000, Science, 290: 84-89; Ravetch J.V. et al., 2001 Annu. Rev. linmunol. 19:275-90; Ravetch J.V. 1994, Cell, 78(4): 553-60). The different Fe receptors, the cells that express them, and their isotype specificity is summarized in Table 1 (adapted from Immunobiology: The Immune System in Health and Disease. 4~ ed. 1999, Elsevier Science Ltd/Garland Publishing, New York). Fcy Receptors [0004] Each member of this family is an integral membrane glycoprotein, possessing extracellular domains related to a C2-set of inimunoglobulin-related domains, a single membrane spanning domain and an intracytoplasmic domain of variable length. There are three known FeRs, designated FcRl(CD64), FcRII(CD32), and FcRIII(CD 16). The three receptors are encoded by distinct genes; however, the extensive homology between the three family members suggest they arose from a common progenitor perhaps by gene duplication. FcyRII(CD32) [00051 FcRli proteins are 4OKDa integral membrane glycoproteins which bind only the complexed IgG due to a low affinity for monomeric Ig (106 lyE'). This receptor is the most widely expressed FcR, present on all heniatopoietic cells, including monocytes, macrophages, B cells, NK cells, neutrophils, mast cells, and platelets. FcRIT has only two linmunoglobulin-like regions in its immunoglobulin binding chain and hence a much lower affinity for IgG than FcRI. There are three human FcyRU genes (FcRfl-A, FcRfl-B, FcRII-C), all of which bind IgG in aggregates or immune complexes. [00061 Distinct differences within the cytoplasmic domains of FcRU-A and FcRII-B create two functionally heterogenous responses to receptor ligation. The fundamental difference is that the A isoform initiates intracellular signaling leading to cell activation such as phagocytosis and respiratory burst, whereas the B isoform initiates inhibitory signals, e.g., inhibiting B-cell activation. Signaling through FcyRs [0007] Both activating and inhibitory signals are transduced through the FcRs following ligation. These diametrically opposing functions result from structural differences among the different receptor isoforms. Two distinct domains within the of the receptor called jinmunoreceptor tyrosine based activation motifs (ITAMs) or immunoreceptor tyrosine based inhibitory motifs (ITIMS) account for the different responses. The recruitment of different cytoplasmic enzymes to these structures dictates the outcome of the FcR-mediated cellular responses. ITAM¬containing FcR complexes include FcRI, FcRIIA, EcRiIIA, whereas ITIM-containing complexes only include FcRIiB. [0008] Human neutrophils express the FcRIIA gene. FcRIIA clustering via immune complexes or specific antibody cross-linldng serves to aggregate ITAMs along with receptor-associated lcinases which facilitate ITAM phosphorylation. ITAM phosphorylation serves as a docking site for Syk kinase, activation of which results in activation of downstream substrates (e.g., PI3K). Cellular activation leads to release of proinflammatory mediators. 100091 The Fcy'RIJB gene is expressed on B lymphocytes; its extracellular domain is 96% identical to FcyRIIA and binds IgG complexes in an indistinguishable manner. The presence of an ITIM in the cytoplasmic domain of FcRIIB defines this inhibitory subclass of FcR. Recently the molecular basis of this inhibition was established. When colligated along with an activating FcR, the ITIM in FcRIIB becomes phosphorylated and attracts the 5H2 domain of the inosital polyphosphate 5'-phosphatase (SHIP), which hydrolyzes phosphoinositol messengers released as a consequence of ITAM-containing FcR¬mediated tyrosine kinase activation, consequently preventing the influx of intracellular Ca~. Thus crosslinking of FcRIIB dampens the activating response to EcR ligation and inhibits cellular responsiveness. B cell activation, B cell proliferation and antibody secretion is thus aborted. TABLE 1. Receptors for the Fe Regions of Immunoglobulin Isotypes (Table Removed) 2.2 DISEASES OF RELEVANCE 2.2.1 CANCER [00101 is a neoplastic mass resulting from abnormal uncontrolled cell growth which can be benign or malignant. Benign tumors generally remain localized. Malignant tumors are collectively termed cancers. The term "malignant" generally means that the tumor can invade and destroy neighboring body structures and spread to distant sites to cause death (for review, see Robbins and Angell, 1976, Basic Pathology, 2d Ed., W.B. Saunders Co., Philadelphia, pp. 68-122). Cancer can arise in many sites of the body and behave differently depending upon its origin. Cancerous cells destroy the part of the body in which they originate and then spread to other part(s) of the body where they start new growth and cause more destruction. 100111 More than 1.2 million Americans develop cancer each year. Cancer is the second leading case of death in the United States and if current trends continue, cancer is expected to be the leading cause of the death by the year 2010. Lung and prostate cancer are the top cancer killers for men in the United States. Lung and breast cancer are the top cancer killers for women in the United States. One in two men in the United States will be diagnosed with cancer at some time during his lifetime. One in three women in the United States will be diagnosed with cancer at some time during her lifetime. (0012] A cure for cancer has yet to be found. Current treatment options, such as surgery, chemotherapy and radiation treatment, are oftentimes either ineffective or present serious side effects. Cancer Therapy [0013] Currently, cancer therapy may involve surgery, chemotherapy, hormonal therapy and/ar radiation treatment to eradicate neoplastic cells in a patient (See, for example, Stockdale, 1998, "Principles of Cancer Patient Management", in Scientific American: M~i~ille vol. 3, Rubenstein and Federman, eds., Chapter 12, Section lV). Recently, cancer therapy could also involve biological therapy or immunotherapy. All of these approaches pose significant drawbacks for the patient Surgery, for example, may be contraindicated due to the health of the patient or may be unacceptable to the patient. Additionally, surgery may not completely remove the neoplastic tissue. Radiation therapy is only effective when the neoplastic tissue exhibits a higher sensitivity to radiation than normal tissue, and radiation therapy can also often elicit serious side effects. Hormonal therapy is rarely given as a single agent and although can be effective, is often used to prevent or delay recurrence of cancer after other treatments have removed the majority of the cancer cells. Biological therapies/immunotherapies are limited in number and may produce side effects such as rashes or swellings, flu-like symptoms, including fever, chills and fatigue, digestive tract problems or allergic reactions. [0014] With respect to chemotherapy, there are a variety of chemotherapeutic agents available for treatment of cancer. A significant majority of cancer chemotherapeutics act by inhibiting DNA synthesis, either directly, or indirectly by inhibiting the biosynthesis of the deoxyribonucleotide triphosphate precursors, to prevent DNA replication and concomitant cell division (See, for example, Oilman etal., Goodman and Gilman's: The Pharmacoloaical Basis of Therapeutics Eighth Ed. (Pergamom Press, New York, 1990)). These agents, which include alkylating agents, such as nitrosourea, anti-metabolites, such as methotrexate and hydroxyurea, and other agents, such as etoposides, campathecins, bleomycin, doxorubicin, daunorubicin, etc., although not necessarily cell cycle specific, kill cells during S phase because of their effect on DNA replication. Other agents, specifically colchicine and the ymca alkaloids, such as vimblastine and vincristine, interfere with microtubule assembly resulting in mitotic arrest. Chemotherapy protocols generally involve administration of a combination of chemotherapeutic agents to increase the efficacy of treatment. [0015] Despite the availability of a variety of chemotherapeutic agents, chemotherapy has many drawbacks (See, for example, Stockdale, 1998, "Principles Of Cancer Patient Management" in Scientific American Medicine. vol.3, Rubenstein and Federman, eds., ch. 12, sect. 10). Almost all chemotherapeutic agents are toxic, and chemotherapy causes significant, and often dangerous, side effects, including severe nausea, bone marrow depression, immunosuppression, etc. Additionally, even with administration of combinations of chemotherapeutic agents, many tumor cells are resistant or develop resist~ce to the chemotherapeutic agents. In fact, those cells resistant to the particular chemotherapeutic agents used in the treatment protocol often prove to be resistant to other drugs, even those agents that act by mechanisms different from the mechanisms of action of the drugs used in the specific treatment; this phenomenon is termed pleiotropic drug or multidrug resistance. Thus, because of drug resistance, many cancers prove refractory to standard chemotherapeutic treatment protocols. [0016] There is a significant need for alternative cancer treatments, particularly for treatment of cancer that has proved refractory to standard cancer treatments, such as surgery, radiation therapy, chemotherapy, and hormonal therapy. A promising alternative is immunotherapy, in which cancer cells are specifically targeted by cancer antigen-specific antibodies. Major efforts have been directed at harnessing the specificity of the immune response, for example, hybridoma technology has enabled the development of tumor selective monoclonal antibodies (See Green MC. etal., 2000 Cancer Treat Rev., 26: 269-286; Weiner LM, 1999 Sernin Oncol. 26(suppl. 14):43-5 1), and in the past few years, the Food and Drug Administration has approved the first MAbs for cancer therapy: Rituxin (anti¬CD2O) for non-Hodgkin's Lyniphoma and Herceptin [anti-(c-erb-2/HER-2)] for metastatic breast cancer (Suzanne A. Eccles, 2001, Breast Cancer Res., 3: 86-90). However, the potency of antibody effector function, e.g., to mediate antibody dependent cellular cytotoxicity ("ADCC") is an obstacle to such treatment. Methods to improve the efficacy of such immunotherapy are thus needed. 2.2.2 INFLAMMATORY DISEASES AND AUTOIMMUNE DISEASES [0017] Inflammation is a process by which the body's white blood cells and chemicals protect our bodies from infection by foreign substances, such as bacteria and viruses. It is usually characterized by pain, swelling, warmth and redness of the affected area. Chemicals known as cytokines and prostaglandins control this process, and are released in an ordered and self-limiting cascade into the blood or affected tissues. This release of chemicals increases the blood flow to the area of injury or infection, and may result in the redness and warmth. Some of the chemicals cause a leak of fluid into the tissues, resulting in swelling. This protective process may stimulate nerves and cause pain. These changes, when occurring for a limited period in the relevant area, work to the benefit of the body. [0018] In autoimmune and/or inflammatory disorders, the immune system triggers an inflammatory response when there are no foreign substances to fight and the body's normally protective immune system causes damage to its own tissues by mistakenly attacking self. There are many different autoimmune disorders which affect the body in different ways. For example, the brain is affected in individuals with multiple sclerosis, the gut is affected in individuals with Crohn's disease, and the synovium, bone and cartilage of various joints are affected in individuals with rheumatoid arthritis. As autoinimune disorders progress destruction of one or more types of body tissues, abnormal growth of an organ, or changes in organ function may result. The autoimmune disorder may affect only one organ or tissue type or may affect multiple organs and tissues. Organs and tissues commonly affected by autoimmune disorders include red blood cells, blood vessels, connective tissues, endocrine glands (e.g, the thyroid or pancreas), muscles, joints, and skin. Examples of autoimmune disorders include, but are not limited to, Hashimoto's thyroiditis, pernicious anemia, Addison's disease, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Sjogren's syndrome, dermatomyositis, lupus erythematosus, multiple sclerosis, autoimmune inner ear disease myasthenia gravis, Reiter's syndrome, Graves disease, autoimmune hepatitis, familial adenomatous polyposis and ulcerative colitis. [0019] Rheumatoid arthritis (RA) and juvenile rheumatoid arthritis are types of inflammatory arthritis. Arthritis is a general term that describes inflammation in joints. Some, but not all, types of arthritis are the result of misdirected inflammation. Besides rheumatoid arthritis, other types of arthritis associated with inflammation include the following: psoriatic arthritis, Reiter's syndrome, ankylosing spondylitis arthritis, and gouty arthritis. Rheumatoid arthritis is a type of chronic arthritis that occurs in joints on both sides of the body (such as both hands, wrists or knees). This symmetry helps distinguish rheumatoid arthritis from other types of arthritis. In addition to affecting the joints, rheumatoid arthritis may occasionally affect the skin, eyes, lungs, heart, blood or nerves. [0020] Rheumatoid arthritis affects about 1% of the world's population and is potentially disabling. There are approximately 2.9 million incidences of rheumatoid arthritis in the United States. Two to three times more women are affected than men. The typical age that rheumatoid arthritis occurs is between 25 and 50. Juvenile rheumatoid arthritis affects 71,000 young Americans (aged eighteen and under), affecting six times as many girls as boys. [00211 Rheumatoid arthritis is an autoimmune disorder where the body's immune system improperly identifies the synovial membranes that secrete the lubricating fluid in the joints as foreign. Inflammation results, and the cartilage and tissues in and around the joints are damaged or destroyed. In severe cases, this inflammation extends to other joint tissues and surrounding cartilage, where it may erode or destroy bone and cartilage and lead to joint deformities. The body replaces damaged tissue with scar tissue, causing the normal spaces within the joints to become narrow and the bones to fuse together. Rheumatoid arthritis creates strffness, swelling, fatigue, anemia, weight loss, fever, and often, crippling pain. Some common symptoms of rheumatoid arthritis include joint stiffness upon awakening that lasts an hour or longer; swelling in a specific finger or wrist joints; swelling in the soft tissue around the joints; and swelling on both sides of the joint. Swelling can occur with or without pain, and can worsen progressively or remain the same for years before progressing. [0022] The diagnosis of rheumatoid arthritis is based on a combination of factors, including: the specific location and symmetry of painful joints, the presence of joint stiffness in the morning, the presence of bumps and nodules under the skin (rheumatoid nodules), results of X-ray tests that suggest rheumatoid arthritis, and/or positive results of a blood test called the rheumatoid factor. Many, but not all, people with rheumatoid arthritis have the rheumatoid-factor antibody in their blood. The rheumatoid factor may be present in people who do not have rheumatoid arthritis. Other diseases can also cause the rheumatoid factor to be produced in the blood. That is why the diagnosis of rheumatoid arthritis is based on a combination of several factors and not just the presence of the rheumatoid factor in the blood . [0023] The typical course of the disease is one of persistent but fluctuating joint symptoms, and after about 10 years, 90% of sufferers will show structural damage to bone and cartilage. A small percentage will have a short illness that clears up completely, and another small percentage will have very severe disease with many joint deformities, and occasionally other manifestations of the disease. The inflammatory process causes erosion or destruction of bone and cartilage in the joints. In rheumatoid arthritis, there is an autoimmune cycle of persistent antigen presentation, T-cell stimulation, cytokine secretion, synovial cell activation, and joint destruction. The disease has a major impact on both the individual and society, causing significant pain, impaired function and disability, as well as costing millions of dollars in healthcare expenses and lost wages. (See, for example, the NIH website and the NIAID website). [00241 Currently available therapy for arthritis focuses on reducing inflammation of the joints with anti-inflammatory or immunosuppressive medications. The first line of treatment of any arthritis is usually anti-inflammatories, such as aspirin, ibuprofen and Cox-2 inhibitors such as celecoxib and rofecoxib. "Second line drugs" include gold, methotrexate and steroids. Although these are well-established treatments for arthritis, very few patients remit on these lines of treatment alone. Recent advances in the understanding of the pathogenesis of rheumatoid arthritis have led to the use of methotrexate in combination with antibodies to cytokines or recombinant soluble receptors. For example, recombinant soluble receptors for tumor necrosis factor (TNF)-ci have been used in combination with methotrexate in the treatment of arthritis. Hiowever, only about 50% of the patients treated with a combination of methotrexate and anti-TNF-a agents such as recombinant soluble receptors for TNF-a show clinically significant improvement. Many patients remain refractory despite treatment. Difficult treatment issues still remain for patients with rheumatoid arthritis. Many current treatments have a high incidence of side effects or cannot completely prevent disease progression. So far, no treatment is ideal, and there is no cure. Novel therapeutics are needed that more effectively treat rheumatoid arthritis and other autoimmune disorders. 2.2.3 INFECTIOUS DISEASES [00251 Infectious agents that cause disease fall into five groups: viruses, bacteria, fungi, protozoa, and helminths (worms). The remarkable variety of these pathogens has caused the natural selection of two crucial features of adaptive immunity. First, the advantage of being able to recognize a wide range of different pathogens has driven the development of receptors on B and T cells of equal or greater diversity. Second, the distinct habitats and life cycles of pathogens have to be countered by a range of distinct effector mechanisms. The characteristic features of each pathogen are its mode of transmission, its mechanism of replication, its pathogenesis or the means by which it causes disease, and the response it elicits. 10026] The record of human suffering and death caused by smallpox, cholera, typhus, dysentery, malaria, etc. establishes the eminence of the infectious diseases. Despite the outstanding successes in control afforded by improved sanitation, immunization, and antimicrobial therapy, the infectious diseases continue to be a common and significant problem of modern medicine. The most common disease of mankind, the common cold, is an infectious disease, as is the feared modem disease AIDS. Some chronic neurological diseases that were thought formerly to be degenerative diseases have proven to be infectious. There is little doubt that the future will continue to reveal the infectious diseases as major medical problems. (0027] An enormous number of human and animal diseases result from virulent and opportunistic infections from any of the above mentioned infectious agents (see Belshe (Ed.) 1984 Textbook of Human Virology. PSG Publishing, Littleton, MA). [0028] One category of infectious diseases are viral infections for example. Viral diseases of a wide array of tissues, including the respiratory tract, CNS, skin, genitourinary tract, eyes, ears, immune system, gastrointestinal tract, and musculoskeletal system, affect a vast number of humans of all ages (see Table 328-2 1n Wyngaarden and Smith, 1988, Cecil Textbook of Medicine~ 18th Ed, W.B. Saunders Co., Philadelphia, pp.l750-l753). Although considerable effort has been invested in the design of effective anti-viral therapies, viral infections continue to threaten the lives of millions of people worldwide. In general, attempts to develop anti-viral drugs have focused on several stages of viral life cycle (See e.g., Mitsuya et al., 1991, FASEB J 5:2369-2381, discussing HIV). However, a common drawback associated with using of many current anti-viral drugs is their deleterious side effects, such as toxicity to the host or resistance by certain viral strains. 3. SUMMARY OF THE INVENTION [0029] The present invention is based, in part, on the identification of mutant human IgGl heavy chain Fe regions, with altered affinities for PcR receptors (e.g., activating FcRs, inhibitory FcRs), using a yeast display system. In vivo animal modeling and clinical experiments indicate that the Fc region plays an essential role in determining the outcome of monoclonal antibody therapy. Current approaches to optimize the Fc region function (e.g., antibody-dependent cell mediated cytotoxicity (ADCC), complement dependent cytotoxicity (CDC) activity) in therapeutic monoclonal antibodies and soluble polypeptides fused to Pc regions have focused on a limited number of single amino acid changes based on structural analysis and/or computer aided designs. Alternative approaches in engineering Pc regions have focused on the glycosylation of the Fc region to optimize Fc region function. The present invention is based, in part, on selecting possible mutants for alteration in one or more Ec functional activities, such as but not limited to ADCC and CDC, from an unbiased library of Fc variants. The present invention provides methods for engineering Pc regions and identification and screening of novel Fc variants outside the expected regions identified by structural studies. Expected regions as used herein refer to those regions that based on structural and/or biochemical studies are in contact with an Fc ligand. [00301 The present invention provides a discovery platform for the identification of Fc variants with improvement in one or more Pc effector function by combining cell based functional assays and combinatorial library construction with state of the art automation. The present invention assembles complete combinatorial libraries by saturating regions of interest within the Fc with modifications that cover all possible amino acid changes. Combinatorial libraries will be tested using a set of binding and functional assays to select mutants based on improved biological function. [0031] Accordingly, the invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fc region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter, e.g., increase or decrease, the affinity of the variant Pc region for an FoyR. Preferably, said onE or more amino acid modification increases the affinity of the variant Pc region for FcyRJJIA and/or FoyRIIA. In a preterred embodiment, the molecules of the invention further specifically bind Pc'YRIIB (via the Fc region) with a lower affinity than a comparable molecule (i.e., having the same amino acid sequence as the molecule of the invention except for the one or more amino acid modifications in the Pc region) comprising the wild-type Pc region binds Pc-yRIIB. In some embodiments, the invention encompasses molecules with variant Pc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Pc region for Fc'yRIIIA and/or FcyRIIA and enhance the affinity of the variant Fe region for PcyRflB relative to a comparable molecule with a wild type Fe region. In other embodiments, the invention encompasses molecules with variant Pc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Pc region for FcRJIIA and/or FcyRIIA but do not alter the affinity of the variant Pc regions for FcyRIIB relative to a comparable molecule with a wild type Pc region. A preferred embodiment is a variant Pc region that has enhanced affinity for FcRIIIA and Fc~yRIIA but reduced affinity for FcyRIIB relative to a comparable molecule with a wild type Fc region. [0032] The Pc variants of the present invention may be combined with other Pc modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Pc variant of the invention with other Fc modifications to provide additive, synergistic, or novel properties in antibodies or Fc fusions. Preferably, the Pc variants of the invention enhance the phenotype of the modification with which they are combined. For example, if an Pc variant of the invention is combined with a mutant known to bind Pc-yRIIIA with a higher affinity than a comparable molecule comprising a wild type Fe region; the combination with a mutant of the invention results in a greater fold enhancement in PcyRIIIA affinity. [0033J In one embodiment, the Pc variants of the present invention may be combined with other known Pc variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et at, 1991, J. Immunol 147:2657-2662; Lund et al, 1992, Mol Immunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1543; Hutchins et al., 1995, Proc NatI. Acad Sci US A92:11980-11984; Jefferis etal, 1995, InimunolLett. ~:l1l-l17; Lundetal., 1995, Pasebi9:115-119; Jefferis etal, 1996,ImmunolLett54:10l-104; Lundetal, 1996,1 lnimtmol 157:49634969; Armour et aL, 1999, Eur J Immunol 29:2613-2624; ldusogie Ct al, 2000, 3 linmunol 164:41784184; Reddy Ct al, 2000, 1 Immunol 164:1925-1933; Xu et at, 2000, Cell Immunol 200:16-26; Idusogie et at, 2001,1 Immunol 166:2571-2575; Shields et al., 2001, 1 Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Left 82:57-65; Presta et aL, 2002, Biochem Soc Trans 30:487-490); US 5,624,821; US 5,885,573; US 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety. In certain embodiemins, the Fe variants of the present invention may be combined with one or more of the Pc variants, i.e., amino acid modifications relative to a wild-type Fe region, presented in tables 5, 6, 7, and 8, i,ifra. [0034] The invention encompasses molecules that are homodimers or heterodimers of Pc regions. Heterodimers comprising Pc regions refer to molecules where the two Pc chains have the same or different sequences. In some embodiments, in the heterodimeric molecules comprising variant Pc regions, each chain has one or more different modifications from the other chain. In other embodiments, in the heterodimeric molecules comprising variant Fe regions, one chain contains the wild-type Pc region and the other chains comprises one or or more modifications. Methods of engineering heterodimeric Fe containing molecules are known in the art and encompassed within the invention. [0035] In some embodiments, the invention encompasses molecules comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Pc region does~not bind any FcR or binds with a reduced affinity, relative to a comparable molecule comprising the wild-type Fe region, as determined by standard assays (e.g., in vitro assays) known to one skilled in the art. In a specific embodiment, the invention encompasses molecules comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one PeR, wherein said PcR is FeylliA. In another specific embodiment, the invention encompasses molecules comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one FcR, wherein said PeR is FoRIIA. In yet another ambodiment, the invention encompasses molecules comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one PcR. wherein said PcR is FeRIIB. [0036] The affinities and binding properties of the molecules of the invention for an FcR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Pc-PcR interactions, L e., specific binding of an Fe region to an FcR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more PcR mediator effector cell functions (See Section 5.2.6). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo. [0037] In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PcRIIIA with a greater affinity than a comparable molecule comprising the wild-type Pc region binds Fc-RIIIA, provided that said variant Fe region does not solely have a substitution at any one of positions 329,331, or 332, and do not include or are not solely substitution with any one of: alanine at any of positions 256, 290, 298, 312, 333, 334, 359, 360, 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a seine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335. [003 8] In another specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeRiIA with a greater affinity than a comparable molecule comprising the wild-type Pc region binds FoyRIIA, provided that the one or more amino acid modifications do not include or are not solely substitution with an alanine at any of positions 256,290,326,255, 258, 267,272,276,280,283,285,286,331,337,268,272, or 430; an asparagine at position 268; a glutamine at position 272; a glutamine, seine, or aspartic acid at position 286; a seine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301. [0039] In a preferred specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule has an altered affinity for an PcR. provided that said variant Pc region does not have a substitution at positions that make a direct contact with PeR based on crystallographic and structural analysis of Pc-PeyR interactions such as those disclosed by Sondermann et al., (2000 Nature, 406: 267-273, which is incorporated herein by reference in its entirety). Examples of positions within the Fe region that make a direct contact with PcR are amino acids 234-23 9 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C'IE loop), and amino acids 327-332 (PIG) loop. In some embodiments, the molecules of the invention comprising variant Pc regions comprise modification of at least one residue that does not make a direct contact with an FcR based on structural and crystallographic analysis, e.g., is not within the Fc-FcR binding site. [0040] In another preferred embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said molecule binds an PeR with an altered affinity relative to a molecule comprising a wild-type Pc region, provided that said at least one amino acid modification do not include or are not solely a substitution at any of positions 255, 256, 258, 267, 268, 269,270,272, 276, 278, 280, 283, 285, 286, 289, 290, 292, 293, 294, 295, 296, 298, 300, 301, 303, 305, 307, 309, 312, 320, 322, 326, 329, 330, 332, 331, 333, 334, 335, 337, 338, 339, 340, 359, 360, 373, 376, 416, 419, 430, 434, 435, 437, 438, 439. In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an FcR with an altered affinity relative to a molecule comprising a wild-type Pc region, provided that said variant Pc region does not include or are not solely a substitution at any of positions 255, 258, 267, 269, 270, 276, 278, 280,283,285,289, 292, 293,294, 295, 296, 300, 303, 305, 307, 309, 322, 329,332, 331, 337, 338, 340, 373, 376,416,419, 434, 435, 437, 438,439 and does not have an alanine at any of positions 256,290, 298, 312, 333, 334, 359, 360 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a seine at position 326; an asparagine at position 326; an 8spartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335 an asparagine at position 268; a glutarnine at position 272; a glutamine, seine, or aspartic acid at position 286; a seine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position 322; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301. [0041] In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region does not include or are not solely a substitution at any of positions 268, 269, 270, 272, 276, 278,283, 285, 286, 289, 292, 293, 301, 303, 305, 307, 309, 331, 333, 334, 335, 337, 338, 340, 360, 373, 376,416,419, 430, 434, 435, 437, 438 or 439 and does not have a histidine, glutamine, or tyrosine at position 280; a serine, glycine, threonine or tyrosine at position 290, a leucine or isoleucine at position 300; an asparagine at position 294, a proline at position 296; a proline, asparagine, aspartic acid, or valine at position 298; a lysine at position 295. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an PeyR with a reduced aflhity relative to a molecule comprising a wild-type Fe region provided that said variant Fe region does not have or are not solely have a substitution at any of positions 252, 254, 265, 268, 269, 270, 278, 289, 292, 293, 294, 295, 296, 298, 300, 301, 303, 322, 324, 327, 329, 333, 335, 338, 340, 373, 376, 382, 388, 389, 414, 416, 419, 434, 435, 437, 438, or 439. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an PcR with an enhanced afThity relative to a molecule comprising a wild-type Pc region provided that said variant Pc region does not have or are not solely a substitution at any of positions 280, 283, 285, 286, 290, 294, 295,298, 300, 301, 305, 307, 309, 312, 315, 331, 333, 334, 337, 340, 360, 378, 398, or 430. [0042] In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region does not include a substitution or does not solely have a substitution at any of positions 330, 243,247,298,241,240,244,263,262, 235,269, or 328 and does not have a leucine at position 243, an asparagine at position 298, a leucine at position 241, and isoleucine or an alanine at position 240, a histidine at position 244, a valine at position 330, or an isoleucine at position 328. [0043] In a specific embodiment, molecules of the invention comprise a variant Fe region having one or more amino acid modifications (e.g., substitutions), which modifications increase the affinity of the variant Fc region for FcRIIIA and/or PeyRIIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Pc region. In certain embodiments, molecules of the invention comprise a variant Pc region having one or more amino acid modifications (e.g., substitutions), which modifications increase the affinity of the variant Pc region for FcRJIIA and/or FcRIIA by greater than 2-fold, at least 4-fold, at least 5-fold, at least 6-fold, at least 8-fold, or at least 10-fold relative to a comparable molecule comprising a wild-type Fe region. In other embodiments of the invention, molecules of the invention comprising a variant Fe region specifically bind PeRIHA and/or FcRIIA with at least 65%, at least 75%, at least 85%, at least 95%, at least 100%, at least 150%, at least 200% greater affinity relative to a molecule comprising a wild-type Fe region. Such measurements are preferably in vitro assays. [0044] The invention encompasses molecules with altered affinities for the activating and/or inhibitory Fey receptors. In particular, the invention contemplates molecules with variant Pc regions, having one or more amino acid modifications, which modifications increase the affinity of the variant Fe region for FcRIIB but decrease the affinity of the variant Fe region for FeRIITA and/or FcRIIA, relative to a comparable molecule with a wild-type Fe region. In other embodiments, the invention encompasses molecules with variant Pc regions, having one or more amino acid modifications, which modifeations decrease the affinity of the variant Fe region for FeRUB and also decrease the affinity of the variant Fe regions for FeRIIIA and/or PeRIIA relative to a comparable molecule with a wild-type Fe region. In yet other embodiments, the invention encompasses molecules with variant Fe regions, having one or more amino acid modifications, which modifeations increase the affinity of the variant Fe region for FeRIiB and also increase the affinity of the variant Fe regions for FcRiIIA and/or PeRIIA relative to a comparable molecule with a wild-type Fe region. In yet other embodiments, the invention encompasses molecules with variant Fe regions, which modifications decrease the affinity of the variant Pc region for Pc'RIIIA and/or FcRIIA but do not alter the affinity of the variant Fe region for FcRJIB relative to a comparable molecule with a wild-type Pc region. In yet other embodiments, the invention encompasses molecules with variant Fe regions, which modifications increase the affinity of the variant Fe region for FcRIIIA and/or FcRIIA but reduce the affinity of the variant Fe region for PeRIIB relative to a comparable molecule with a wild-type Fe region. [0045] In a specific embodiment, the molecules of the invention comprise a variant Fe region, having one or more amino acid modifications (e.g., substitutions), which one or more modifications increase the affinity of the variant Fe region for FcRiIIA and decrease the affinity of the variant Fe region for PoRIIB, relative to a comparable molecule comprising a wild-type Fe region which binds FcRIIIA and FcRIIB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications are not a substitution with alanine at any of positions 256, 298, 333, or 334. [00461 In another specific embodiment, the molecules of the invention comprise a variant Fe region, having one or more amino acid modifications (e.g., substitutions), which one or more modifications increase the affinity of the variant Pc region for FcRIIA and decrease the affinity of the variant Fe region for FcRIIB, relative to a comparable molecule comprising a wild-type Fe region which binds FeRIIA and PeRIIB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications is not a substitution with arginine at position 320. [0047] In most preferred embodiments, the molecules of the invention with altered affinities for activating and/or inhibitory receptors having variant Fe regions, have one or more amino acid modifications, wherein said one or more amino acid modification is a substitution at position 288 with asaparagine, at position 330 with seine and at position 396 with leucine (MgPclO) (See Tables 5 & 6); or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFcl3); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 392 with threonine, and at position 396 with leucine (MgFc3 8); or a substitution at position 221 with glutamic acid, at position 270 with glutamic acid, at position 308 with alanine, at position 311 with bistidine, at position 396 with leucine, and at position 402 with aspartic acid (MgFc42); or a substitution at position 240 with alanine, and at position 396 with leucine (MgPc52); or a substitution at position 410 with histidine, and at position 396 with leucine (MgPc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with seine, and at position 396 with leucine (MgFcS4); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc5 5); or a substitution at position 370 with glutamic acid and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine (MgPel 55); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine. In a related embodiment, the variant Fe region further comprises one or more amino acid modifications disclosed in tables 5, 6, 7, and 8. infra. [0048] The preferred method for screening and identifying molecules comprising variant Fe regions with altered FcR affinities (e.g., enhanced FcRIIIA affinity) is yeast surface display technology (for review see Boder and Wittrup, 2000, Methods in Enzymology, 328: 43 0-444, which is incorporated herein by reference in its entirety). Specifically, the yeast surface display is a genetic method whereby polypeptides comprising Pc mutants are expressed on the yeast cell wall in a form accessible for interacting with PcR. Yeast surface display of the mutant Pc containing polypeptides of the invention may be performed in accordance with any of the techniques known to those skilled in the art or the specific methods described herein. Yeast display offers the advantage of utilizing actual binding to a desired receptor to identify variant Fe regions that have enhanced binding to that receptor. [00491 One aspect of the invention provides a method for selecting mutant Fe fusion proteins with a desirable binding property, e.g., the ability of the mutant Fe fusion protein to bind FcRIIIA with a greater affinity than a comparable polypeptide comprising a wild-type Fe region binds FcRIllA. Yeast cells displaying the mutant Fe fusion proteins can be screened and characterized by any biochemical or immunological based assays known to those skilled in the art for assessing binding interactions. In a specific embodiment, screening of mutant Pc fusion proteins is done using one or more biochemical based assays, e.g., an ELISA assay. [00501 In preferred embodiments, screening and identifying molecules comprising variant Fe regions with altered PcR affinities (e.g, enhanced FcyRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Pc-FcR interaction, i.e., specific binding of an Pc region to an FcR, including, but not limited to, an ELISA assay, surface plasmon resonance assays, unmunoprecipitation assay, affinity chromatography, and equilibrium dialysis. In some embodiments, screening and identifying molecules comprising variant Fe regions with altered PcR affinities (e.g., enhanced FcRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more functional based assays, preferably in a high throughput manner. The functional based assays can be any assay known in the art for characterizing one or more PcR mediated effector cell function such as those described herein in Section 5.2.6. Non-limiting examples of effector cell functions that can be used in accordance with the methods of the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity (ADCC), antibody-dependent phagocytosis, phagocytosis, opsonization, opsonophagocytosis, cell binding, rosetting, Clq binding, and complement dependent cell mediated cytotoxicity. In some embodiments, screening and identifying molecules comprising variant Pc regions with altered PcR affinities (e.g., enhanced FcRilIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays in combination or in parallel with one or more functional based assays, preferably in a high throughput manner. [0051] A preferred method for measuring the PeR-Fe interaction in accordance with the invention is an assay developed by the inventors, which allows detection and quantitation of the interaction, despite the inherently weak affinity of the receptor for its ligand, e.g., m the micromolar range for PeRLIB and PeyRiIIA. The method involves the formation of an PcR complex (e.g., FcyRIIIA, FcRliB) that has an improved avidity for an Fe region, relative to an uncomplexed Pc-yR. In a specific embodiment, the invention encompasses a method for producing a tetrameric FcR complex, wherein said tetrameric complex has an enhanced affinity for an Fe region, relative to the affinity of a monomeric PcR for the Fe region, said method comprising: (i) producing a fusion protein, such that a 15 amino acid AVITAG sequence operably linked to the soluble region of FcR (ii) biotinylating the protein produced using an E. coli BirA enzyme; (iii) mixing the biotinylated protein produced with streptaividn-phycoerythrin in an appropriate molar ratio, such that a tetrameric FcR complex is formed. [0052] In a preferred embodiment of the invention, polypeptides comprising Fe regions bind the tetrameric FcR complexes, formed according to the methods of the invention, with at least an 8-fold higher affinity than they bind the monomeric uncomplexed FcR The binding of polypeptides comprising Fe regions to the tetrameric FcR complexes may be determined using standard techniques known to those skilled in the art, such as for example, fluorescence activated cell sorting (FACS), radioirnmunoassays, ELISA assays, etc. [0053] The invention encompasses the use of the immune complexes formed according to the methods described above for determining the functionality of molecules comprising an Fe region in cell-based or cell-free assays. [00541 In a specific embodiment, the invention provides modified immunoglobulins comprising a variant Pc region with an enhanced affinity for FcRiIIA and/or PcyRIIA. Such immunoglobulins include IgG molecules that naturally contain FcR binding regions (e.g., Pc'yRIIIA and/or PeRIIB binding regions), or immunoglobulin derivatives that have been engineered to contain an FcR binding region (e.g., FcRILIA and/or FcRIIB binding regions). The modified immunoglobulins of the invention include any immunoglobulin molecule that binds, preferably, immunospecifically, i.e., competes off non-specific binding as determined by immunoassays well known in the art for assaying specific antigen-antibody binding, an antigen and contains an PeR binding region (e.g., a PeRIIIA and/or PeRJIB binding region). Such antibodies include, but are not limited to, polyclonal, monoclonal, bi¬specific, multi-specific, human, humanized, chimeric antibodies, single chain antibodies, Fab fragments, F(ab') fragments, disulfide-linked Fvs, and fragments containing either a VL or VH domain or even a complementary determining region (CDR) that specifically binds an antigen, in certain cases, engineered to contain or fused to an PcR binding region. [00551 In certain embodiment, the invention encompasses immunoglobulins comprising a variant Pc region with an enhanced affinity for PeyRIiIA and/or PcRflA such that the immunogiobulin has an enhanced effector function, e.g. antibody dependent cell mediated cytotoxicity. The effector function of the molecules of the invention can be assayed using any assay described herein or known to those skilled in the art. In some embodiments, immunoglobulins comprising a variant Fe region with an enhanced affinity for PeRIIIA and/or FcRiIA have an enhanced ADCC activity relative to wild-type by at least 2-fold, at least 4-fold, at least 8-fold, at least 10-fold, at least 50-fold, or at least 100-fold. [0056] The invention encompasses engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Pc region by modification (e.g., substitution, insertion, deletion) of one or more amino acid residues, which modifications modulate the affinity of the therapeutic antibody for an FcR activating receptor and/or an PeR inhibitory receptor. In one embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fe region by modification of one or more amino acid residues, which modifications increase the affinity of the Fe region for PeRJIIA and/or PcRIIA. In another embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fe region by modification of one or more amino acid residues, which modification increases the affinity of the Fe region for FcRHIA and/or FcR.UA and further decreases the affinity of the Fe region for FcR]IB. The engineered therapeutic antibodies may further have an enhanced effector function, e.g., enhanced ADCC activity, phagocytosis activity, etc., as determined by standard assays known to those skilled in the art. [00571 In a specific embodiment, the invention encompasses engineering a humanized monoclonal antibody specific for Her2/neu protooncogene (e.g., Ab4D5 humanized antibody as disclosed in Carter etal., 1992, Proc. Nati. Acad. Sci. USA 89:4285-9) by modification (e.g, substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Pc rgion for FcRIIIA and/or PeyRITA. In another specific embodiment, modification of the humanized Her2/neu monoclonal antibody may also further decrease the affinity of the Pc region for FcRIIB. In yet another specific embodiment, the engineered humanized monoclonal antibodies specific for Her2/neu may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. [00581 In another specific embodiment, the invention encompasses engineering an anti-CD2O antibody by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Pc rgion for FcRIIIA and/or FcRiIA. In a related embodiment, the anti-CD2O antibody is mouse human chimeric anti-CD2O monoclonal antibody, 2117 Further nonlimiting examples of anti-CD2O atibodies that can be used in the methods of the inventionare disclosed in U.S. Patent Application No.: 11/271,140, filed November 10, 2005, hereby incorporated by reference in its entirety. in another specific embodiment, modification of the anti-CD2O monoclonal antibody, 2117 may also further decrease the affinity of the Pc region for PeRIIB. In yet another specific embodiment, the engineered anti-CD2O monoclonal antibody, 2117 may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. [00591 In another specific embodiment, the invention encompasses engineering an anti-FcRflB antibody, in particular an anti-FcRflB antibody that specifically binds human PeyRUB, more particularly native human Pc'yRUB, by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the a~nity of the Fc rgion for FcRTILA and/or FcRTIA. Non-limiting examples of representaive anti-FcRflB antibodies are disclosed in U.S. Provisional Application No. 60/403,266 filed on August 12,2002; U.S. Application No. 10/643,857 flIed on August 14, 2003; and U.S Patent Application Publication No.s: 2004-0185045; 2005-0260213; and 2006-00138 10, all of which are hereby incorporated by reference in their entireties. Examples of anti-FcRIIB antibodies that may be engineered in accordance with the methods of the invention are the monoclonal antibodies produced by clone 2B6, 3117, 8B5.4.3, lDS, 2E1, 2119, 2D11 and 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA- 76 10, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (deposited at ATCC, 10801 University Boulevard, Manassas, VA 02209-2011, all of which are incorporated herein by reference), or chimeric, humanized or other engineered versions thereof. [0060] In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain and/or light chain variable domain of 2B6, 3117 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the CDRs of 2B6, 3117 or 8B5.3.4. In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO: 1, SEQ ID NO:2 or SEQ ID NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO: 4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7 or SEQ ID NO: 8. In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ II) NO:9 and the light chain variable domain having the amino acid sequence of SEQ ID NO:l0. [00611 In another specific embodiment, modification of the anti-FcRJIB antibody may also further decrease the affinity of the Pc region for PeRUB. In yet another specific embodiment, the engineered anti-PeyRTIB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. In a specific embodiment, the anti-FcRIIB monoclonal antibody comprises a modification at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFcl3); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine (MgFc29); or a substitution at positon 392 with threonine and at position 396 with leucine (MgFc3 8); or a substitution at position 221 with glutamic acid, at positon 270 with glutaniic acid, at positon 308 with alanine, at position 311 with histidine, at position 396 with leucine, and at position 402 with aspartic (MgFc42); or a substitution at position 410 with histidine, and at position 396 with leucine (MgPc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgPc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFcS5); or a substitution at position 370 with glutamic acid, and at position 396 with leucine (MgFc59) ; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgFcl55); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine. In a related embodiment, the variant Pc region further comprises one or more amino acid modifications disclosed in tables 5, 6, 7, and 8, infra. [0062] The present invention also includes polynucleotides that encode a molecule of the invention, including polypeptides and antibodies, identified by the methods of the invention. The polynucleotides encoding the molecules of the invention may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. The invention relates to an isolated nucleic acid encoding a molecule of the invention. The invention also provides a vector comprising said nucleic acid. The invention further provides host cells containing the vectors or polynucleotides of the invention. [0063] The invention further provides methods for the production of the molecules of the invention. The molecules of the invention, including polypeptides and antibodies, can be produced by any method known to those skilled in the art, in particular, by recombinant expression. In a specific embodiment, the invention relates to a method for recombinantly producing a molecule of the invention, said method comprising: (i) culturing in a medium a host cell comprising a nucleic acid encoding said molecule, under conditions suitable for the expression of said molecule; and (ii) recovery of said molecule from said medium. [0064] The molecules identified in accordance with the methods of the invention are useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcR is desired, e.g., cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC. [0065] In one embodiment, the invention encompasses a method of treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that binds the cancer antigen, which has been engineered in accordance with the methods of the invention. In a specific embodiment, the invention encompasses a method for treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds said cancer antigen, said therapeutic antibody comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said therapeutic antibody specifically binds FcRIIIA with a greater affinity than the therapeutic antibody comprising the wild-type Fe region binds Fc'yRIIIA, provided that said variant Pc region does not have a substitution at positions 329, 331, or 332, and does not have an alanine at any of positions 256,290, 298, 312, 333, 334, 359, 360, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a seine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamic acid at position 334; a methionine at position 334; a bistidine at position 334; a valine at position 334; or a leucine at position 334. In another specific embodiment, the invention encompasses a method for treating cancer in a patient having a cancer characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds a cancer antigen, said therapeutic antibody comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region such that said therapeutic antibody specifically binds FcRIHA with a greater affinity than a therapeutic antibody comprising the wild-type Pa region binds FcTRflIA, and said therapeutic antibody further specifically binds FcTRJIB with a lower affinity than a therapeutic antibody comprising the wild-type Pc region binds FcRflB, provided that said variant Pc region does not have an alanine at any of positions 256,298,333, or 334. The invention encompasses a method for treating cancer in a patient characterized by a cancer antigen, said method comprising administering a therapeutically effective amount of a therapeutic antibody that specifically binds said cancer antigen and said therapeutic antibody comprises a variant Fe region so that the antibody has an enhanced ADCC activity. (00661 The invention encompasses a method of treating an autoimmune disorder and/or inflammatory disorder in a patient in need thereof, said method comprising administering to said patient a therapeutically effective amount of a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild type Pc region, such that said molecule specifically binds FcRIIB with a greater affinity than a comparable molecule comprising the wild type Pc region, and said molecule further specifically binds FcRIHA with a lower affinity than a comparable molecule comprising the wild type Pc region., and said molecule binds an immune complex (e.g., an antigen/antibody complex). The invention encompasses a method of treating an autoimmune disorder and/or inflammatory disorder further comprising administering one or more additional prophylactic or therapeutic agents, e.g., m,munomodulatory agents, anti-inflammatory agents, used for the treatment and/or prevention of such diseases. 100671 The invention also encompasses methods for treating or preventing an infectious disease in a subject comprising administering a therapeutically or prophylactically effective amount of one or more molecules of the invention that bind an infectious agent or cellular receptor therefor. Infectious diseases that can be treated or prevented by the molecules of the invention are caused by infectious agents including but not limited to viruses, bacteria, fungi, protozae, and viruses. [0068) According to one aspect of the invention, molecules of the invention comprising variant Pc regions have an enhanced antibody effector function towards an infectious agent, e.g., a pathogenic protein, relative to a comparable molecule comprising a wild-type Pc region. In a specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing phagocytosis and/or opsonization of the infectious agent causing the infectious disease. In another specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing ADCC of infected cells causing the infectious disease. [00691 In some embodiments, the molecules of the invention may be administered in combination with a therapeutically or prophylactically effective amount of one or additional therapeutic agents known to those skilled in the art for the treatment and/or prevention of an infectious disease. The invention contemplates the use of the molecules of the invention in combination with antibiotics known to those skilled in the art for the treatment and or prevention of an infectious disease. [0070] The invention provides pharmaceutical compositions comprising a molecule of the invention, e.g., a polypeptide comprising a variant Pc region, an immunoglobulin comprising a variant Pc region, a therapeutic antibody engineered in accordance with the invention, and a pharmaceutically acceptable carrier. The invention additionally provides pharmaceutical compositions further comprising one or more additional therapeutic agents, including but not limite to anti-cancer agents, anti-inflammatory agents, immunomodulatory agents. 3.1 DEFINITIONS [00711 As used herein, the term "Pc region" is used to define a C-terminal region of an IgO heavy chain. Although the boundaries may vary slightly, the human IgG heavy chain Pc region is defined to stretch from 0ys226 to the carboxy terminus. The Pc region of an IgG comprises two constant domains, CH2 and C113. The CH2 domain of a human IgG Fc region (also referred to as "C'y2" domain) usually extends from amino acid 231 to amino acid 338. The CH3 domain of a human IgG Fc region usually extends from amino acids 342 to 447. The CH2 domain is unique in that it is not closely paired with another domain. Rather, two N-linked branched carbohydrate chains are interposed between the two CH2 domains of an intact native IgG. [00721 Throughout the present specification, the numbering of the residues in an IgG heavy chain is that of the EU index as in Kabat et al., Secjuences of Proteins of Immunological Interest. 5~ Ed. Public Health Service, NH1, MD (1991), expressly incorporated herein by references. The "EU index as in Kabat" refers to the numbering of the human IgGi EU antibody. [00731 The "hinge region" is generally defined as stretching from Glu2l6 to Pro23O of human IgGl. Hinge regions of other IgCl isotypes may be aligned with the IgGl sequence by placing the first and last cysteine residues forming inter-heavy chain S-S bonds in the same positions. [0.0741 As used herein, the terms "antibody" and "antibodies" refer to monoclonal antibodies, multispecific antibodies, human antibodies, humanized antibodies, synthetic antibodies, chimeric antibodies, polyclonal antibodies, camelized antibodies, single-chain Fvs (scPv), single chain antibodies, Fab fragments, F(ab') fragments, disulfide-linked bispecific Pvs (sdFv), intrabodies, and anti-idiotypic (anti-Id) antibodies (including, e.g., anti-Id and anti-anti-Id antibodies to antibodies of the invention), and epitope-binding fragments of any of the above. In particular, antibodies include immunoglobulin molecules and immunologically active fragments of immunoglobulin molecules, i.e., molecules that contain an antigen binding site. Immunoglobulin molecules can be of any type (e.g., IgG, IgE, 1gM, IgD, IgA and IgY), class (e.g., IgGi, 1g02, IgG3, IgG4, IgA1 and IgA2) or subclass. [0075] As used herein, the term "derivative" in the context of polypeptides or proteins refers to a polypeptide or protein that comprises an amino acid sequence which has been altered by the introduction of amino acid residue substitutions, deletions or additions. The term "derivative" as used herein also refers to a polypeptide or protein which has been modified, Le, bythe covalent attachment of any type of molecule to the polypeptide or protein. For example, but not by way of limitation, an antibody may be modified, e.g., by giycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by knQwn protectingfblocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. A derivative polypeptide or protein may be produced by chemical modifications using techniques known to those of skill in the art, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Further, a derivative polypeptide or protein derivative possesses a similar or identical function as the polypeptide or protein from which it was derived. [00761 As used herein, the term "derivative" in the context of a non-proteinaceous derivative refers to a second organic or inorganic molecule that is formed based upon the structure of a first organic or inorganic molecule. A derivative of an organic molecule includes, but is not limited to, a molecule modified, e.g., by the addition or deletion of a hydroxyl, methyl, ethyl, carboxyl or amine group. An organic molecule may also be esterifled, alkylated and/or phosphorylated. [00771 As used herein, the terms "disorder" and "disease" are used interchangeably to refer to a condition in a subject. In particular, the term "autoimmune disease" is used interchangeably with the term "autoirnmune disorder" to refer to a condition in a subject characterized by cellular, tissue and/or organ injury caused by an immunologic reaction of the subject toitso~ cells, tissues and/or organs. The term "inflammatory disease" is used interchangeably with the term "inflammatory disorder" to refer to a condition in a subject characterized by inflammation, preferably chronic inflammation. Autoimmune disorders may or may not be associated with inflammation. Moreover, inflammation may or may not be caused by an autoimmune disorder. Thus, certain disorders may be characterized as both autoimmune and inflammatory disorders. [00781 As used herein, the term "cancer" refers to a neoplasm or tumor resulting from abnormal uncontrolled growth of cells. As used herein, cancer explicitly includes, leukemias and lymphomas. In some embodiments, cancer refers to a benign tumor, which has remained localized. In other embodiments, cancer refers to a malignant tumor, which has invaded and destroyed neighboring body structures and spread to distant sites. In some embodiments, the cancer is associated with a specific cancer antigen. [0079] As used herein, the term "immunomodulatory agent" and variations thereof refer to an agent that modulates a host's immune system. In certain embodiments, an immunomodulatory agent is an inimunosuppressant agent. In certain other embodiments, an immunomodulatory agent is an immunostimulatory agent. Immunomodatory agents include, but are not limited to, small molecules, peptides, polypeptides, fusion proteins, antibodies, inorganic molecules, mimetic agents, and organic molecules. [0080] As used herein, the term "epitope" refers to a fragment of a polypeptide or protein or a non-protein molecule having antigenic or immunogenic activity in an animal, preferably in a mammal, and most preferably in a human. An epitope having immunogenic activity is a fragment of a polypeptide or protein that elicits an antibody response in an animal. An epitope having antigenic activity is a fragment of a polypeptide or protein to which an antibody immunospecifically binds as determined by any method well-known to one of skill in the art, for example by immunoassays. Antigenic epitopes need not necessarily be immunogenic. [0081] As used herein, the term "fragment" refers to a peptide or polypeptide comprising an amino acid sequence of at least 5 contiguous amino acid residues, at least 10 contiguous amino acid residues, at least 15 contiguous amino acid residues, at least 20 contiguous amino acid residues, at least 25 contiguous amino acid residues, at least 40 contiguous amino acid residues, at least 50 contiguous amino acid residues, at least 60 contiguous amino residues, at least 70 contiguous amino acid residues, at least contiguous 80 amino acid residues, at least contiguous 90 amino acid residues, at least contiguous 100 amino acid residues, at least contiguous 125 amino acid residues, at least 150 contiguous amino acid residues, at least contiguous 175 amino acid residues, at least contiguous 200 ammo acid residues, or at least contiguous 250 amino acid residues of the amino acid sequence of another polypeptide. In a specific embodiment, a fragment of a polypeptide retains at least one function of the polypeptide. [00821 As used herein, the terms "nucleic acids" and "nuclcotide sequences~~ include DNA molecules (e.g., eDNA or genomic DNA), RNA molecules (e.g., xnRNA), combinations of DNA and RNA molecules or hybrid DNA/RNA molecules, and analogs of DNA or RNA molecules. Such analogs can be generated using, for example, nucleotide analogs, which include, but are not limited to, inosine or tritylated bases. Such analogs can also comprise DNA or RNA molecules comprising modified backbones that lend beneficial attributes to the molecules such as, for example, nuclease resistance or an increased ability to cross cellular membranes. The nucleic acids or nucleotide sequences can be single-stranded, double-stranded, may contain both single-stranded and double-stranded portions, and may contain triple-stranded portions, but preferably is double-stranded DNA. [0083] As used herein, a "therapeutically effective amount" refers to that amount of the therapeutic agent sufficient to treat or manage a disease or disorder. A therapeutically effective amount may refer to the amount of therapeutic agent sufficient to delay or minimize the onset of disease, e.g., delay or minimize the spread of cancer. A therapeutically effective amount may also refer to the amount of the therapeutic agent that provides a therapeutic benefit in the treatment or management of a disease. Further, a therapeutically effective amount with respect to a therapeutic agent of the invention means the amount of therapeutic agent alone, or in combination with other therapies, that provides a therapeutic benefit in the treatment or management of a disease. [0084] As used herein, the terms "prophylactic agent" and "prophylactic agents" refer to any agent(s) which can be used in the prevention of a disorder, or prevention of recurrence or spread of a disorder. A prophylactically effective amount may refer to the amount of prophylactic agent sufficient to prevent the recurrence or spread of hyperproliferative disease, particularly cancer, or the occurrence of such in a patient, including but not limited to those predisposed to hyperproliferative disease, for example those genetically predisposed to cancer or previously exposed to carcinogens. A prophylactically effective amount may also refer to the amount of the prophylactic agent that provides a prophylactic benefit in the prevention of disease. Further, a prophylactically effective amount with respect to a prophylactic agent of the invention means that amount of prophylactic agent alone, or in combination with other agents, that provides a prophylactic benefit in the prevention of disease. [0085] As used herein, the terms "prevent", "preventing" and "prevention" refer to the prevention of the recurrence or onset of one or more symptoms of a disorder in a subject as result of the administration of a prophylactic or therapeutic agent. [00861 As used herein, the term "in combination" refers to the use of more than one prophylactic and/or therapeutic agents. The use of the term "in combination" does not restrict the order in which prophylactic and/or therapeutic agents are administered to a subject with a disorder. A first prophylactic or therapeutic agent can be administered prior to (e.g., 5 minutes, i~ minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks before), concomitantly with, or subsequent to (e.g., 5 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 8 weeks, or 12 weeks after) the administration of a second prophylactic or therapeutic agent to a subject with a disorder. [00871 "Effector function" as used herein is meant a biochemical event that results from the interaction of an antibody Fe region with an Pc receptor or ligand. Effector functions include but are not limited to antibody dependent cell mediated cytotoxicity (ADOC), antibody dependent cell mediated phagocytosis (ADCP), and complement dependent cytotoxicity (CDC). Effector functions include both those that operate after the binding of an antigen and those that operate independent of antigen binding. [0088] "Effector cell" as used herein is meant a cell of the immune system that expresses one or more Pc receptors and mediates one or more effector functions. Effector cells include but are not limited to monocytes, macrophages, neutrophils, dendritic cells, eosinophils, mast cells, platelets, B cells, large granular lymphocytes, Langerhans' cells, natural killer (NK) cells, and may be from any organism including but not limited to humans, mice, rats, rabbits, and monkeys. [0089] "Pc ligand" as used herein is meant a molecule, preferably a polypeptide, from any organism that binds to the Pc region of an antibody to form an Pc-ligand complex. Pc ligands include but are not limited to PcRs, FcRs, PcyRs, PcRn, Clq, C3, staphylococcal protein A, streptococcal protein G, and viral PcR. Fe ligands may include undiscovered molecules that bind Pc. 4. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 SCHEMATIC OF SEQUENCE OF 8B5.3.4 VARIABLE LIGHT CHAIN DOMAIN [0090] Depiction of the 8B5.3.4 VL nucleotide and amino acid sequence (SEQ ID NOS:ll and 10, respectively). FIG. 2 SCHEMATIC OF SEQUENCE OF 8B5.3.4 VARIABLE HEAVY CHAIN DOMAIN [0091] Depiction of the of the 8B5.3.4 VII nucleotide and amino acid sequence (SEQ ID NOS:12 and 9, respectively). FIG. 3 SDS-PAGE ANALYSIS OF RECOMBINANT SOLUBLE FcR [00921 The purity of recombinant soluble FcR proteins was assessed by 10% polyacrylamide gel electrophoresis. The gels were stained with Coomassie blue. Lane 1: purified recombinant soluble PeyRITIA; Lane 2: molecular weight marker; Lane 3: molecular weight marker; Lane 4: purified recombinant soluble PcRIIB. The dashes refer to the molecular weight of the markers, from top to bottom, they correspond to a molecular weight of 98, 50, 36, and 22 KDa respectively. FIG. 4 ELISA ASSAY OF RECOMBINANT SOLUBLE Fc7R [0093] The direct binding of purified recombinant soluble FcRIIIA to aggregated and monomeric IgG was determined using an ELISA assay. Binding of (A) aggregated IgG with 3G8; (•) Biotinylated IgG; (in) aggregated IgG; (X) aggregated IgG with mouse IgGl. FIGs. 5 A and B CHARACTERIZATION OF FcRIIIA TE¶IRAMERIC COMPLEX USING AN ELISA ASSAY A. Soluble tetrameric PcyRTIIA complex binds soluble monomeric human IgG specifically. Binding of soluble tetrameric FcyRUIA to human IgG is blocked by 3G8 a mouse anti-FcllIA monoclonal antibody; the 4-4-20 monoclonal antibody harboring the D265A mutation was not able to block the binding of soluble tetrameric FoyRIIJA to aggregated human IgO (A). B. Binding of soluble tetrameric FcyRIIIA complex to soluble monomeric human IgO (in) is compared to the binding of monomeric soluble PcyRIIIA to soluble monomeric human IgO (•). FIGS. 6 A and B CHARAC1~RIZATION OF FcyRIILA TETRAMERIC COMPLEX USING A MAGNETIC BEAD ASSAY A. FcRTILA Complex: two PcRIIIA(filled shape) are joined by a monoclonal antibody DJI3Oc (1~ Ab); the anti-mouse P(ab)2 is conjugated to FE (circle). B. FAGS analysis of FcRIIIA bound to Pc coated beads: (a) beads alone; (b) complex without FcyRIIIA; (c) complex with FcyRUIA; (d) complex with FcRIHA and LNK16. HG. 7 SCHEMATIC PRESENTATION OF Fc CONTAINING CONSTRUCTS [0094] A schematic diagram of the IgGi Pc domains cloned into pYDi is presented. The open box represents the hinge-CH2-CH3 domains; parallel vertical lines represent the CHl domain. In the case of the 01F206 and 227 constructs; the N-terminal amino acids are shown. The underlined residues correspond to the hinge region; the * represents the Xpress epitope tag; hatched boxes represent the 01y4-Ser linker, and the stippled boxes represent the Aga2p gene. FIGS. 8A-H FAUS ANALYSIS OF THE Fc FUSION PROTEINS ON THE YEAST CELL WALL 100951 Cells were incubated with either a PE-conjugated polyclonal goat anti-human Pc antibody (FIGS. 8A-D) or with HP6017 (Sigma), a mouse anti-human IgOl Pc (CH3) specific monoclonal antibody (FIGS. 8E-I{). A and E represent vector alone; Panels B and F represent the CHl-CH3 construct; Panels C and G represent the 01F227; and Panels D and H represent the OLE 206 construct. FIGS. 9A-C BINDING OF SOLUBLE TETRAMERIC FcyRJIIA TO THE SURFACE DISPLAYED Fe FUSION PROTEINS [0096] Cells containing pYDl-CHl (A); pYD-CHl-D265A (B); and pYD vector (C) were grown under conditions to express Aga2p fusion proteins on the cell surface. Cells were incubated with PeyRIIIA at 0.15 mM , 7.5 mM , and 7.5 mM, respectively, and analyzed by FAGS. FIG. 10 CHARACTERIZATION OF THE BINDING OF SOLUBLE TETRAMERIC FcTRJLIA TO THE SURFACE DISPLAYED Fc FUSION PROTEINS [00971 Binding of PcyRIUA tetrameric complex to Pc fusion proteins on the yeast cell surface was analyzed. PE-conjugated FcyRUIA tetrameric complexes were pre-incubated with different concentrations of 308 (•), LNK (A) or an irrelevant isotype control (in), and subsequently incubated with the yeast cells. Cells were analyzed by FAGS for PE fluorescence. The percent cells that bound the FcyRIILA tetrameric complex were plotted on the y-axis. FIG. 11 EXAMPLE OF SORT GATE FOR SELECTING Fc MUTANTS WITH INCREASED BINDING TO FcRIIIA [0098] Cells were stained with PE-conjugated FcyRUIA tetrameric complexes (y¬axis) and anti-Pc-FITC conjugated antibody (x-axis). Boxed area represents sort gate set to select —1.0% of the cell population. FIGS. 12A-N FACS ANALYSIS OF SOME OF THE Fc MUTANTS IDENTIFIED HAVING AN INCREASED AFFINITY FOR FcRHIA TETRAMERIC COMPLEXES [0099] Individual clones harboring the pYD-CHl plasmid containing independent Fc mutations were amplified in selective media containing glucose, induced for Pc expression in selective media containing galactose, and subsequently analyzed by PACs. FIGS. 12A and B represent cells harboring wild-type Fe; FIGS. 12C and D represent mutant #5; FIGS. 12E and F represent mutant # 20; FIGS. 12G and H represent mutant # 21; FIGS. 12 1 and J represent mutant # 24; FIGS. 12K and L represent mutant # 25; PIGS. 12M and N represent mutant # 27. Cells were stained with Pc'yRIIIA tetrameric complex (FIGS. 12 A, C, E, G, I, K, and M) or PcyRIIB tetrameric complex (FIGS. 12 B, D, F, H, J, L, and N). FIGS. 13 A-B CHARACTERIZATION OF Fc MUTANTS IN THE 4-4-20 MONOCLONAL ANTIBODY BY ELISA [00100] Pc domains from the pYD-CHi plasmids were cloned into the heavy chain of the chimeric 4-4-20 monoclonal antibody. The 4-4-20 monoclonal antibody was expressed in 293 cells and supernatants were collected. ELISA plates were coated with fluoresceine conjugated BSA to capture the chimeric 4-4-20 mutant antibodies. FcyRIIIA (A) and FcyRflB (B) receptors were then coated onto the ELISA plates to which the 4-4-20 monoclonal antibodies had been absorbed in order to determine the relative affinities of the variant receptors to the Pc domains. Mutants # 15 and #29 were non-binding isolates included as controls. FIG. 14 ADCC ACTIVITY OF MUTANTS IN THE 4-4-20 MONOCLONAL ANTIBODY [001011 4-4-20 antibodies containing mutant Fc regions were assessed for their ADOC activity, and compared to the ADCC activity of a wild type 4-4-20 antibody. The mutants analyzed are as follows: MGFc-l0 (K288N, A33 OS, P396L), MGPc-26 (D265A), MGFc-27 (G316D, A378V, D399E), MGFc28 (N3 151, A379M, D399E), MGFc29 (P2431, V379L, 0420V), MGPc3O (F275V), MGFc-31 (P247L, N421K), MGFc-32 (D280E, S354P, A431D, L4411), MGPc-33 (K317N, P423 deleted), MGPc-34 (F241L, E258G), MGPc-35 (R255Q, K326E), MGFc-36 (K218R, G281D, G385R) FIGS. 15 A and B ADCC ACTIVITY OF MUTANTS IN THE HER2INEU ~JMANIZED MONO CLONAL ANTIBODY A. Humanized HER2/neu monoclonal antibodies containing mutant Pc regions were assessed for their ADCC activity and compared to the ADCC activity of a wild type Her2/neu antibody. The mutants analyzed are as follows: MGFc-5 (V379M), MGFc-9 (P2431, V379L), MGPc-10 (K288N, A330S, P396L), MGPo-13 (K334E, T359N, T3665), MGFc-27 (G3 16D, A378Y, D399E). B. ADCC activity of additional mutants in the context of the humanized Her2/neu monoclonal antibody MGFc-37 (K248M), MGFc-39 (E293V Q295E, A327T), MGFc-38 (K392T, P396L), MGPc-41 (H268N, P396L), MGFc-23 (K334E, R292L), MGFc-44, MGFc¬ 45. Two independent clones were teseted for each mutant. FIG. 16 CAPTURE OF CII 4-4-20 ANTIBODY ON BSA-FITC SURFACE [00102] 6 .LL of antibody at a concentration of approximately 20 pg/mL was injected at 5~Umin over a BSA- fluoroscein isothiocyanate (FITC) surface. BlAcore sensogram of the binding of ch 4-4-20 antibodies with mutant Fe regions on the surface of the BSA-PITC immobilized sensor ship is shown. The marker was set on wild-type captured antibody response. FIG. 17 SENSOGRAM OF REAL TIME BINDING OF FcyRflIA TO CH 4-4-20 ANTIBODIES CARRYING VARIANT Pc REGIONS [001031 Binding of PeyRIIIA to ch-4-4-20 antibodies carrying variant Pc regions was analyzed at 200 nM concentration. Responses were normalized at the level of ch-4-4-20 antibody obtained for wild-type. [001041 Mutants used were as follows: Mut 6 (5219V), Mut 10 (P396L, A3305, K288N);Mut 18 (K326E); Mut 14 (K334E, K288N); Mut 11 (R255L, F243L); Mut 16 (P372Y); Mut 19 (K334N, K2461). FIGS. 18 A-H ANALYSIS OF KINETIC PARAMETERS OF FcyRflIA BINDING TO ANTIBODIES CARRYING VARIANT Fe REGIONS [001051 Kinetic parameters for PcRflIA binding to antibodies carrying variant Fc regions were obtained by generating separate best fit curves for 200 nM and 800 nM. Solid line indicates an association fit which was obtained based on the k0ff values calculated for the dissociation curves in the 32-34 sec interval. K~1 and k0ff values represent the average from two cencentrations. FIG. 19 SENSOGRAM OF REAL TIME BINDING OF FcyRIIB-Fc FUSION PROTEINS TO ANTIBODIES CARRYING VARIANT Fc REGIONS [00106] Binding of Fc'yRIIB-Fc fusion proteins to ch4-4-20 antibodies carrying variant Fe regions was analyzed at 200 nM concentration. Responses were normalized at the level of ch-4-4-20 antibody obtained for wild type. FIGs. 20 A-C ANALYSIS OF KINETIC PARAMETERS FcyRITB-Fc FUSION PROTEINS TO ANTIBODIES CARRYING VARIANT Fe REGIONS [00107] Kinetic parameters for PeyRIIB-Fe binding to antibodies carrying variant Pc regions were obtained by generating separate best fit curves for 200 nM and 800 nM. Solid line indicates an association fit which was obtained based on the ~ values calculated for the dissociation curves in the 32-34 sec. interval. Kd and K~ values represent the average from two concentrations. [001081 Mutants used were as follows: Mut 6 (S2 19V), Mut 10 (P396L, A330S, K288N); Mut 18 (K326E); Mut 14 (K334E, K288N); Mut 11 (R255L, F243L); Mut 16 (P372Y); Mut 19 (K334N, K2461). FIG. 21 RATIOS OF K0 (WT)(Kor (MUT) FOR FcRIIIA-Fe PLOTfED AGAINST ADCC DATA [001091 Numbers higher than one show a decreased dissociation rate for PeyRIIIA binding and increased dissociation rate for FcRIIB-Fe binding relative to wild-type. Mutants in the box have lower off rate for FcyRIIIA binding and higher off rate for PeyRIIB¬Pc binding. FIG. 22 COMPETITION WITH UNLABELED FcRIIIA [00110] A kinetic screen was implemented to identify Pc region mutants with improved K0ff rates for binding PeyRIIIA. A library of Fe region variants containing P396L mutation was incubated with 0.1 pM biotinylated FcRIIIA-Linker-Avitag for one hour and then washed. Subsequently 0.8 µM unlabeled FcRIIIA was incubatd with the labeled yeast for different time points. Yeast was spun down and unlabeled FcRIIIA was removed, Receptor bound yease was stained with SA (streptavidin):PE (phycoerythrin) for FACS analysis. VK~S. 23 A-C FACS ANALYSIS BASED ON THE KINETIC SCREEN [00111] Based on the calculated Kori. from the data presented in FIG. 22, a one minute time point selection was chosen. A 10-fold excess of library was incubated with 0.1 pM biotinylated FcyRIIIA-Linker-Avitag monomer; cells were washed and incubated with unlabeled ligand for one minute; then washed and labeled with SA:PE. The cells were then sorted by FACS, selecting the top 0.3% binders. The nonselcted P396L library was compared to the yeast cells selected for improved binding by PACS. The histograms show the percentage of cells that are costained with both FcRIIIA /PE and goat anti-human Fe/PITO. FIGS. 24 A-B SELECTION BASED ON SOLiD PHASE DEPLETION OF FcyRIIB Fc BINDERS [00112] A. The P396L library was screened based on PcRIIB depletion and Fc'yRIIIA selection using magnetic beads. The PcRIIB depletion by magnetic beads was repeated 5 times. The resulting yeast population was analyzed and found to show greater than 50% cell staining with goat anti-human Pc and a very small percentage of cells stained with PcRIIIA. Subsequently cells were selected twice by FACS using 0.1 idvl biotinylated FcRflIA linker-avitag. Yeast cells were analyzed for both FcRJIIA and FcRIIB binding after each sort and compared to wild type binding. B. Pc Mutants were selected from the FcyRIIB depleted yeast population using biotinylated FcyRflIA 15SF linker avitag monomer as a ligand. The sort gate was set to select the top 0.25% PcRUIA 158P binders. The resulting enriched population was analyzed by FACS for binding to the different PcRIIIA (158F and 158V), FcRIIIB and PeRIIA (13 lR). FIG. 25 RELATIVE RATES OF SKBR3 TARGET CELL LYSIS MEDIATED BY CHIMERIC 41)5 HARBORING FC MUTANTS [00113) Relative rates of lysis was calculated for each Pc mutant tested. Lysis rates for 4D5 antibody with Fe mutants were divided by the rate of lysis mediated by wild type 4D5 antibody. Data from at least 2 independent assays were averaged and plotted on the histogram. For each Fe mutant data from two different antibody concentrations are shown. The antibody concentrations were chosen to flank the point along the curve at which lysis was —50%. FIG. 26 RELATIVE RATES OF DAUDI CELL LYSIS MEDIATED BY CH[MERIC 2H7 HARBORING FC MUTANTS [00114] Relative rates of lysis was calculated for each Fe mutant tested. Lysis rates for 2H7 antibody with Pc mutants were divided by the rate of lysis mediated by wild type 2H7 antibody. Data from at least 1-2 independent assays were averaged and plotted on the histogram. For each Pc mutant, data from two different antibody concentrations are shown The antibody concentrations were chosen based on the point along the curve at which lysis was '-'50%. FIG. 27 SCHEME FOR LIBRARY PRODUCTION. [00115] DNA strands are represented. Forward arrows represent primers containing mutant codons. Reverse arrow represent reverse gene specific oligo. FIG. 28 STRATEGY FOR PRODUCTION OF LIBRARIES BY BUILD A GENE PROTOCOL. [00116] The rectangular boxes represent the hinge, CH2, and CH3 domains, respectively. The short black lines represent the double stranded oligos with 5 overhangs. FIG. 29 NOVEL Fe MUTANTS IMPROVE PBMC MEDIATED ADCC IN SKBR3 CELLS. [00117] The plot shows linear regression analysis of a standard ADCC assay. Antibody was titrated over 3 logs using an effector to target ratio of 75:1. % lysis = (Experimental release — SR)/(MR-SR) * 100. FIG. 30 NOVEL Fe MUTANTS IMPROVE PBMC MEDIATED ADCC IN DAUDI CELLS. [001181 The plot shows linear regression analysis of a standard ADCC assay. Antibody was titrated over 3 logs using an effector to target ratio of 75:1. % lysis = (Experimental release — SR)/(MR-SR) * 100. FIG. 31 Fc RECPETOR PROFILES VIA FACS UPON CVTOK[NE TREATMENT OF MONOCYTES. [001191 Cytokine treatment of monocytes increases low affinity Fe receptor expression Elutriated monocytes were cultured using specific cytokines in serum free media. Pc receptor proffies were assayed using FAGS. FIG. 32 IMPROVED TUMOR CELL KILLING USING FC MUTANTS IN MACROPHAGE-DERIVED MONO CYTES BASED ADCC. [00120] Ch4D5 MAb concentration over 2 logs was tested using effector:target ratio of 35:1. Percent lysis was calculated as in FIG. 30. FIG. 33 COMPLEMENT DEPENDENT CYTOTOXICITY ASSAY FLOW CHART. [00121] The flow chart summarizes the CDC assays used. FIG.34 COMPLEMENT DEPENDENT CYTOTOXICITY ACTIVITY [00122) Pc mutants that show enhanced binding to Pc'yRIIIA also showed improved complement activity. Anti-CD2O ChMAb over 3 orders of magnitude was titrated. Percent lysis was calculated as in as in FIG. 30. FIG. 35 DECISION TREE FOR SELECTION OF Fc MUTANTS [00123) An exemplary protocol for selecting Pc mutants. FIG. 36 Clq BINDING TO 2B6 ANTIBODY [00124] A. The diagram depicts the BlAcore format for analysis of 2B6 binding to the first component of the complement cascade. [00125] B. Sensogram of real time binding of 2B6 antibody carrying variant Fe regions to Clq. FIGS. 37 A-I) Clq BINDING TO 2B6 MUTANT ANTIBODY. [00126] Sensogram of real time binding of 2B6 mutants to Clq (3.25nM). Mutants depicted at MgPcSl (Q419H, P396L); MgFcSl/60 in Panel A; MgPc55 and MgPcS5/60 (Panel B), MgFc59 and MgFc59/60 (Panel C); and MgFc3l/60 (Panel D). FIGS. 38 A-D Fe VARIANTS WITH DECREASED BINDING TO FcRIIB [00127] Binding of PcR to ch4D5 antibodies to compare effect of D270E (60) on R255L, P396L double mutant (MgPc5 5). KD was analyzed at different concentrations of PeR; 400nM CDl6A 158V; 800nM CDl6A 158P; 200nM CD32B; 200nM CD32A 131H. Analysis was performed using separate KD using Biacore 3000 software. FIGS. 39 A-D KINETIC CHARACTERISTICS OF 4D5 MUTANTS SELECTED FROM FcRIIB DEPLETIONSIFcyRRAH131 SELECTION [00128] Binding of FcR to ch4D5 antibodies carrying different Fe mutations selected by CD32B depletion and CD32A H13 1 screening strategy. K~3 was analyzed at different concentrations of PcR 400nM CDl6A 158V; SOOnM CDl6A 158P; 200nM CD32B; 200nM CD32A 13 lH. Analysis was performed using separate KD using Biacore 3000 software. FIG. 40. PLOT OF MDM ADCC DATA AGAINST THE KOFF DETERMINED FOR CD32A 131H BINDING AS DETERMINED BY BIACORE. [00129] The mutants are as follows: MgFc 25 (E333A, K334A, 5298A); MgPc68 (D270E); MgFc38 (K392T, P396L); MgPc55 (R255L, P396L); MgPc3 1 (P247L, N421K); MgPc59(K370E, P3 96L). FIGS. 41 A-B. ADCC ACTIVITY OF MUTANTS IN A HER2INEU CHIMERIC MONOCLONAL ANTIBODY [00130) Chimeric HER2lneu monoclonal antibodies containing mutant Pc regions were assessed, in duplicate, for their ADCC activity and compared to the ADCC activity of the wild type, chimeric Her2/neu antibody. The mutants analyzed are as follows: MOFc88 (P243L, R292P, Y300L, V3051, P396L), MGPc88A (F243L, R292P, Y300L, P396L), MGFcl55 (F243L, R292P, Y300L). FIGS. 42 A-B. ESTIMATED TUMOR WEIGHT IN MICE TREATED WITH WILD-TYPE OR Fe MUTANT h2B6 [00131] Balb/c nude mice were inoculated subcutaneously with Daudi cells and administered 25 jig, 2.5 pg or 0.25 µg weekly doses of either wild-type h2B6 (A) or h2B6 harboring Pc mutant MGFc 0088 (F243L, R292P, Y300L, V3051, P396L) (B). Mice administered buffer alone were used as control. Tumor wieght was calculated based on the estimated volume of the subcutaneous tumor according to the formula (width2 X length)/2. FIGS. 43 A-B. SURVIVAL IN TUMOR BEARING MICE TREATED WITH WILD-TYPE OR Fc MUTANT h2B6 100132] Nude mice were inoculated with Daudi cells and administered 25 pg, 2.5 jig or 0.25 pg weekly doses of either wild-type h2B6 (A) or b2B6 harboring Pc mutant MGPc 0088 (F243L, R292P, Y300L, V3051, P396L) (B). Mice administered buffer alone were used as control. 5. DESCRIPTION OF THE PREFERRED EMBODIMENTS [001331 The present invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Fe region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter, e.g., increase or decrease, the affinity of the variant Pc region for an PcR. hi some embodiments, the invention comprises modifications to the Fe region including but not limited to any of the modifications disclosed in U.S. Application Serial No. 10/754,922 filed Jaunuary 9,2004; U.S. Provisional Application Serial No. 60/43 9,498 filed Jaunuary 9,2003; U.S. Provisional Application Serial No. 60/456,041 filed March 19, 2003; U.S. Provisional Application Serial No. 60/5 14,549 filed October 23, 2003 and U.S. Provisional Application Serial No. 60/587,251 filed July 12,2004. Each of the above mentioned applications is incorporated herein by reference in its entirety. In some embodiments, the invention provides molecules comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, which variant Pc region binds FcRIIIA with a greater affinity, relative to a comparable molecule, i.e., being the same as said molecule with a variant Fe region but not having the one or more amino acid modifications, comprising the wild-type Pc region as determined by methods known to one skilled in the art for determining Pc-PcR interactions and methods disclosed herein, for example, an ELISA assay or a surface plasmon resonance assay. In yet other embodiments, the invention encompasses molecules comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, which variant Fe region binds FcRIIIA with a reduced affinity relative to a comparable molecule comprising the wild-type Pc region. In a preferred embodiment, the molecules of the invention further specifically bind PcRIIB (via the Pc region) with a lower affinity than a comparable molecule comprising the wild-type Pc region binds Pc'RIIB. In some embodiments, the invention encompasses molecules comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, which variant Fe region binds FcRIIIA and FcRIiB with a greater affinity, relative to a comparable molecule comprising the wild-type Pc region. In other embodiments, the invention encompasses molecules comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, which variant Pc region binds FcRflB with a greater affinity, relative to a comparable molecule comprising the wild-type Pc region. In other embodiments, the invention encompasses molecules comprising variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, which variant Pc region binds FcRIIE with a reduced affinity, relative to a comparable molecule comprising the wild-type Fe region. [001341 In some embodiments, the invention encompasses molecules comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fc region does not show a detectable binding to any FcR (e.g., does not bind PeRIIA, PcRIIB, or PeRJIIA, as determined by, for example, an ELISA assay), relative to a comparable molecule comprising the wild-type Pc region. [00135] In a specific embodiment, the invention encompasses molecules comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one PeyR, wherein said PeyR is PeyIilA. In another specific embodiment, the invention encompasses molecules comprising a variant Fc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one PcR, wherein said FcR is PeRIIA. In yet another ambodiment, the inve~ition encompasses molecules comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild type Fe region, which variant Fe region only binds one PeR, wherein said FcR is FcRIIB. The invention particularly relates to the modification of human or humanized therapeutic antibodies (e.g, tumor specific anti-angiogenic or anti-inflammatory monoclonal antibodies) for enhancing the efficacy of therapeutic antibodies by enhancing, for example, the effector function of the therapeutic antibodies, e.g., enhancing ADCC. [00136] The affinities and binding properties of the molecules of the invention for an PcR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Pc-FcR interactions, i.e., specific binding of an Fe region to an FcR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more PeR mediator effector cell functions (See Section 5.2.7). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo. [00137] In some embodiments, the molecules of the invention comprising a variant Fe region comprise at least one amino acid modification in the CH3 domain of the Fe region, which is defined as extending from amino acids 342-447. In other embodiments, the molecules of the invention comprising a variant Fe region comprise at least one amino acid modification in the CH2 domain of the Fe region, which is defined as extending from amino acids 231-341. In some embodiments, the molecules of the invention comprise at least two amino acid modifications, wherein one modification is in the CH3 region and one modification is in the CH2 region. The invention further encompasses amino acid modification in the hinge region. Molecules of the invention with one or more amino acid modifications in the CH2 and/or CH3 domains have altered affinities for an PcR as determined using methods described herein or known to one skilled in the art. [00138] In a particular embodiment, the invention encompasses amino acid modification in the CHl domain of the Pc region. [00139] In particularly preferred embodiments, the invention encompasses molecules comprising a variant Pc region wherein said variant has an increased binding to FcRIIA (CD32A) and/or an increased ADGO activity, as measured using methods known to one skilled in the art and exemplified herein. The ADCC assays used in accordance with the methods of the invention may be NK dependent or macrophage dependent. [001401 The Fe variants of the present invention may be combined with other known Pc modifications including but not limited to modifications which alter effector function and modification which alter PcR binding affinity. In a particular embodiment, an Pc variant of the invention comprising a first amino acid modification in the CH3 domain, C112 domain or the hinge region may be combined with a second Pc modification such that the second Fe modification is not in the same domain as the first so that the first Pc modification confers an additive, synergistic or novel property on the second Pc modification. In some embodiments, the Fe variants of the invention do not have any amino acid modification in the CH2 domain. [00141) The Pc variants of the present invention may be combined with any of the known Pc modifications in the art such as those disclosed in Table 2 below. TABLE 2. (Table Removed) In other embodiments, the Pc variants of the present invention may be combined with any of the known Pc modifications in the art such as those disclosed in Tables 3 A and B below. (Table Removed) TABLE 3B (Table Removed) ** Note that table uses EU numbering as in Kabat. 4~(k~4~1 In a-vr.f@rred specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule has an altered affinity for an FcR, provided that said variant Pc region does not have a substitution at positions that make a direct contact with FcR based on crystallographic and structural analysis of Fc-PcR interactions such as those disclosed by Sondermann et al., 2000 (Nature, 406: 267-273 which is incorporated herein by reference in its entirety). Examples of positions within the Pc region that make a direct contact with PcR are amino acids 234-239 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C'/E loop), and amino acids 327-332 (PIG) loop. In some embodiments, the molecules of the invention comprising variant Pc regions comprise modification of at least one residue that makes a direct contact with an PeR based on structural and crystallographic analysis. 1001441 The FcR interacting domain maps to the lower hinge region and select sites within the CH2 and CH3 domains of the IgG heavy chain. Amino acid residues flanking the actual contact positions and amino acid residues in the CH3 domain play a role in IgG/FcR interactions as indicated by mutagenesis studies and studies using small peptide inhibitors, respectively (Sondermann et al., 2000 Nature, 406: 267-273; Diesenhofer et at, 1981, Biochemistry, 20: 2361-2370; Shields et al., 2001, J. Biol. Chem. 276: 6591-6604; each of which is incorporated herein by reference in its entirety). Direct contact as used herein refers to those amino acids that are within at least 1 A, at least 2, or at least 3 angstroins of each other or within 1 A, 1.2 A, 1.5 A, 1.7 A or 2 A Van Der Waals radius. An exemplary list of previously identified sites on the Pc that effect binding of Pc interacting proteins is listed in the Table 4 below. In some embodiments, the invention encompasses Pc variants that do not have any modifications at the sites listed below. In ether embodiments, the invention encompasses Pc variants comprising amino acid modifications at one or more sites listed below in combination with other modifications disclosed herein such that such modification has a synergistic or additive effect on the property of the mutant PilI~IOUSLY IDENTIFIED SITES ON TIlE Fc THAT EFFECT BINDING OF Fc INTERACTING PROTEINS. (Table Removed) • ~0AUA5k '1~bk,4 lists sites within the Pc region that have previously been identified to be important for the Pc-PeR interaction. Columns labeled PcR-Fc identifies the Pc chain contacted by the PcR. Letters identify the reference in which the data was cited. C is Shields et at., 2001, J. Biol. Chem. 276: 6591-6604; D is Jefferis et at., 1995, linmunol. Lett. 44:111-7; E is Hinton et at; 2004, J. Biol. Chem. 279(8): 6213-6; P is Idusogie et al., 2000, J. linmunol. 164: 4178-4184; each of which is incorporated herein by reference in its entirety. [001461 In another preferred embodiment, the invention encompasses a molecule. comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an Pc'yR with an altered affinity relative t~ a molecule comprising a wild-type Pc region, provided that said variant Pc region does not have or is not solely a substitution at any of positions 255, 256, 258, 267,268,269, 270, 272, 276, 278, 280, 283, 285, 286, 289, 290, 292,293, 294, 295, 296, 298, 300, 301, 303, 305, 307, 309, 312, 320, 322, 326, 329, 330, 332, 331, 333, 334, 335, 337, 338, 339, 340, 359, 360, 373, 376, 416, 419,430, 434, 435, 437,438, 439. In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an PeR with an altered affinity relative to a molecule comprising a wild-type Pc region, provided that said variant Pc region does not have or is not solely a substitution at any Qf positions 255,258,267,269, 270, 276, 278,280,283,285, 289, 292,293, 294, 295,296, 300, 303, 305, 307, 309, 322, 329, 332, 331, 337, 338, 340,373,376,416,419,434,435,437,438,439 and does not have an alanine at any of positions 256,290,298, 312, 333, 334, 359, 360; 326, or 430; a lysine at position 330; a threonine at position 339; a methionine at position 320; a serine at position 326; an asparagine at position 326; an aspartic acid at position 326; a glutamic acid at position 326; a glutamine at position 334; a glutamie acid at position 334; a methionine at position 334; a histidine at position 334; a valine at position 334; or a leucine at position 334; a lysine at position 335 an asparagine at position 268; a glutamine at position 272; a glutamine, seine, or aspartic acid at position 286; a serine at position 290; a methionine, glutaniine, glutamic acid, or arginine at position 320; a glutanile acid at position 322; a seine, glutamie acid, or aspartic acid at position 326; a lysine at position 330; a glutanilne at position 335; or a methionine at position 301. [00147] In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region does not have or is not solely a substitution at any of positions 268,269,270,272,276,278,283,285,286,289,292,293, 3flL~3Q~5,2Q7~09~ 331, 333, 334, 335, 337, 338, 340, 360, 373, 376, 416, 419, 430, 434,435, 437,438 or 439 and does not have a histidine, glutaniine, or tyrosine at position 280; a seine, glycine, threonine or tyrosine at position 290, a leucine or isoleucine at position 300; an asparagine at position 294, a proline at position 296; a proline, asparagine, aspartic acid, or valine at position 298; a lysine at position 295. In yet another preferred embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said molecule binds an PeyR with a reduced alThity relative to a molecule comprising a wild-type Pc region provided that said variant Fe region does not have or is not solely a substitution at any of positions 252, 254, 265, 268, 269, 270,278, 289, 292, 293, 294, 295, 296, 298, 300, 301, 303, 322, 324, 327, 329, 333, 335, 338, 340, 373, 376, 382, 388, 389, 414,416,419,434,435,437,438, or 439. in yet another preferred embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said molecule binds an FcR with an enhanced affnity relative to a molecule comprising a wild-type Fe region provided that said variant Pc region does not have or is not solely a substitution at any of positions 280,283, 285, 286, 290,294, 295, 298, 300, 301, 305, 307, 309, 312, 315, 331, 333, 334, 337, 340, 360, 378, 398, or 430. [001481 In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Fe region does not include or are not solely a substitution at any of positions 330, 243, 247, 298,241, 240, 244, 263, 262, 235, 269, or 328 and does not have a leucine at position 243, an asparagine at position 298, a leucine at position 241, and isoleucine or an alanine at position 240, a bistidine at position 244, a valine at position 330, or an isoleucine at position 328. [001491 In most preferred embodiments, the molecules of the invention with altered affinities for activating and/or inhibitory receptors having variant Pc regions, have one or aiore amino acid modifications, wherein said one or more amino acid modification is a ~ubstitution at position 288 with asaparagine, at position 330 with seine and at position 396 vith leucine (MgFclO)(See Tables 5 & 6); or a substitution at position 334 with glutamic icid, at position 359 with asparagine, and at position 366 with serine (MgPc 13); or a ubstitution at position 316 with aspartic acid, at position 378 with valine, and at position ~99 with glutamic acid (MgPc27); or a substitution at position 392 with threonine, and at osition 396 with leucine (MgPc3 8); or a substitution at position 221 with glutaniic acid, at iosition 270 with glutamic acid, at position 308 with alanine, at position 311 with histidine, tt position 396 with leucine, and at position 402 with aspartic acid (MgFc42); or a with alanine, and at position 396 with leucine (MgFc52); or a substitution at position 410 with histidine, and at position 396 with leucine (MgPc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgPcS4); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc5 5); or a substitution at position 370 with glutamic acid and at position 396 with leucine (MgFc59) ; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgPc8 8); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgPc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgPcl 55); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine. 100150] In one specific embodiment, the invention encompasses a molecule comprising a variant Pc region wherein said variant Fe region comprises a substitution at position 396 with leucine, at position 270 with glutamic acid and at position 243 with leucine. In another specific embodiment the molecule further comprises one or more amino acid modification such as those disclosed herein. [001511 In some embodiments, the invention encompasses molecules comprising a variant Fe region having an amino acid modification at one or more of the following positions: 119, 125,132,133,141,142,147,149,162,166,185,192,202,205,210, 214, 217, 219, 215,216,217, 218,219, 221,222, 223, 224, 225,227,288, 229,231, 232, 233, 235,240, 241,242,243,244,246,247,248,250,251,252,253,254,255,256, 258,261, 262, 263, 268, 269,270, 272, 273,274, 275, 276,279,280, 281, 282,284,287,288,289, 290,291,292,293,295, 298, 300, 301, 303, 304,305, 306, 307,308,309, 310, 311, 312, 313, 315, 316, 317, 318, 319, 320, 323, 326, 327, 328, 330, 333, 334, 335, 337, 339, 340, 343,344, 345, 347, 348, 352, 353, 354, 355, 358, 359, 360, 361, 362, 365, 366, 367, 369, 370, 371, 372, 375, 377, 378, 379,380, 381, 382, 383, 384, 385, 386, 387,388, 389, 390, 392, 393, 394, 395, 396, 397, 398, 399,400,401,402,404,406,407,408,409,410,411, 412,414,415,416417,419,420,421,422,423,424,427,428,431,433, 435,436,438, 440,441,442,443,446,447. Preferably such mutations result in molecules that have an altered a~nity for an Fc)'R and/or have an altered effecteor cell mediated function as [00152] disclosed and exemplified herein and known to one skilled in the art. The invention encompasses molecules comprising variant Fe regions consisting of or comprising any of the mutations listed in the table below in Table 5. TABLE 5. EXEMPLARY MUTATIONS (Table Removed) [00 153] In yet other embodiments, the invention encompasses molecules comprising variant Pc regions having more than two amino acid modifications. A non-limiting example of such variants is listed in the table be1~w (1'able 6). The invention encompasses mutations listed in Table 6 which further comprise one or more amino acid modifications such as those disclosed herein. TABLE 6. EXEMPLARY COMBINATION VARIANTS (Table Removed) [00154] In some embodiments, the molecules, preferably the immunoglobulins of the invention fi.irther comprise one or more glycosylation sites, so that one or more covalently attached to the molecule. Preferably, the antibodies of the invention with one or more glycosylation sites and/or one or more modifications in the Fe region have an enhanced antibody mediated effector function, e.g., enhanced ADOC activity. In some embodiments, the invention further comprises antibodies comprising one or more modifications of amino acids that are directly or indirectly known to interact with a carbohydrate moiety of the antibody, including but not limited to amino acids at positions 241, 243, 244, 245, 245, 249, 256, 258, 260, 262, 264, 265,296,299, and 301. Amino acids that directly or indirectly interact with a carbohydrate moiety of an antibody are known in the art, see, e.g., Jefferis et al., 1995 Immunology Letters, 44:111-7, which is incorporated herein by reference in its entirety. [00155] The invention encompasses antibodies that have been modified by introducing one or more glycosylation sites into one or more sites of the antibodies, preferably without altering the functionality of the antibody, e.g., binding activity to PeyR. Glycosylation sites may be introduced into the variable and/or constant region of the antibodies of the invention. As used herein, "g1yco~ylation sites" include any specific amino acid sequence in an antibody to which an oligosaceharide (i.e., carbohydrates containing two or more simple sugars linked together) will specifically and covalently attach. Oligosaceharide side chains are typically linked to the backbone of an antibody via either N-or 0-linkages. N-linked glycosylation refers to the attachment of an oligosaceharide moiety to the side chain of an asparagine residue. 0-linked glycosylation refers to the attachment of an oligosaccharide moiety to a hydroxyamino acid, e.g., serine, threonine. The antibodies of the invention may comprise one or more glycosylation sites, including N-linked and 0-linked glycosylation sites. Any glycosylation site for N-linked or 0-linked glycosylation known in the art may be used in accordance with the instant invention. An exemplary N-linked glycosylation site that is useful in accordance with the methods of the present invention, is the amino acid sequence: Asn-X-Thr/Ser, wherein X may be any amino acid and Thr/Ser indieates a threonine or a serine. Such a site or sites may be introduced into an antibody of the invention using methods well known in the art to which this invention pertains. See, for example, "In Vitro Mutagenesis." Recombinant DNA: A Short Course. J. D. Watson, et al. W.H. Freeman and Company, New York, 1983, chapter 8, pp. 106-116, which is incorporated herein by reference in its entirety. An exemplary method for introducing a glycosylation site into an antibody of the invention may comprise: modifying or mutating an amino acid sequence of the antibody so that the desired Asn-X-Tbr/Ser sequence is obtained. mbodiments, the invention encompasses methods of modifying the carbohydrate content of an antibody of the invention by adding or deleting a glycosylation site. Methods for modifying the carbohydrate content of antibodies are well known in the art and encompassed within the invention, see, e.g.,U.S. PatentNo. 6,218,149;EP 0359 096 Bi; U.S. Publication No. US 2002/0028486; WO 03/035835; U.S. Publication No. 2003/0115614; U.S. PatentNo. 6,218,149; U.S. PateutNo. 6,472,511; all of which are incorporated herein by reference in their entirety. In other embodiments, the invention encompasses methods of modifying the carbohydrate content of an antibody of the invention by deleting one or more endogenous carbohydrate moieties of the antibody. In a specific embodiment, the invention encompasses shifting the glycosylation site of the Fe region of an antibody, by modifying positions adjacent to 297. In a specific embodiment, the invention encompasses modifying position 296 so that position 296 and not position 297 is glycosylated. 5.1 POLYPEPTIDES AND ANTIBODIES WITH VARIANT Fc REGIONS [001571 The present invention is based, in part, on the identification of mutant human IgGi heavy chain Fe regions, with altered affinities for different PcR receptors, using a yeast display system. Accordingly, the invention relates to molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Pc region, having one or more amino acid modifications (e.g., substitutions, but also including insertions or deletions) in one or more regions, which modifications alter the affinity of the variant Fe region for an PeR. 100158] It will be appreciated by one skilled in the art that aside from amino acid substitutions, the present invention contemplates other modifications of the Fe region amino acid sequence in order to generate an Pc region variant with one or more altered properties, e.g., altered effeetor function. The invention contemplates deletion of one or more amino acid residues of the Pc region in order to reduce binding to an FcR. Preferably, no more than 5, no more than 10, no more than 20, no more than 30, no more than 50 Fe region residues will be deleted according to this embodiment of the invention. The Fe region herein comprising one or more amino acid deletions will preferably retain at least about 80%, and preferably at least about 90%, and most preferably at least about 95%, of the wild type Fe region. In some embodiments, one or more properties of the molecules are maintained such as for example, non-inimunogenicity, FeRIIIA binding, PeRIIA binding, or a combination of these properties. 40Ol5~M ln~altema embodiments, the invention encompasses amino acid insertion to generate the Pc region variants, which variants have altered properties including altered effector function. In one specific embodiment, the invention encompasses introducing at least one amino acid residue, for example one to two amino acid residues and preferably no more than 10 amino acid residues adjacent to one or more of the Pc region positions identified herein. In alternate embodiments, the invention further encompasses introducing at least one amino acid residue, for example one to two amino acid residues and preferably no more than 10 amino acid residues adjacent to one or more of the Fe region positions known in the art as impacting PeR interaction and/or binding. [00160] The invention further encompasses incorporation of unnatural amino acids to generate the Fe variants of the invention. Such methods are known to those skilled in the art such as those using the natural biosynthetic machinery to allow incorporation of unnatural amino acids into proteins, see, e.g., Wang et al., 2002 Chem. Comm. 1:1-11; Wang et al., 2001, Science, 292: 498-500; van Tiest et aL, 2001. Chem. Comm. 19: 1897-1904, each of which is incorporated herein by reference in its entirety. Alternative strategies focus on the enzymes responsible for the biosynthesis of amino acyl-tRNA, see, e.g., Tang et al., 2001, J. Am. Chem. 123(44): 11089-11090; Kiick et al., 2001, PEBS Lett. 505(3): 465; each of which is incorporated herein by reference in its entirety. [001611 The affinities and binding properties of the molecules of the invention for an FoR are initially determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Pc-PeR interactions, i.e., specific binding of an Fe region to an PeR including but not limited to ELISA assay, surface plasmon resonance assay, inimunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of the molecules of the invention are also characterized by in vitro functional assays for determining one or more Fc~'R mediator effector cell functions (See Section 5.2.7). In most preferred embodiments, the molecules of the invention have similar binding properties in in vivo models (such as those described and disclosed herein) as those in in vitro based assays However, the present invention does not exclude molecules of the invention that do not exhibit the desired phenotype in in vitro based assays but do exhibit the desired phenotype in vivo. A representative flow chart of the screening and characterization of molecules of the invention is described in FIG. 35. [00162] The invention encompasses molecules comprising a variant Pc region that binds with a greater affinity to one or more PeRs. Such molecules preferably mediate effector function more effectively as discussed infra. In other embodiments, the invention encompasses molecules comprising a variant Fe region that bind with a weaker affinity to or elimination of effector function is desirable in certain cases for example in the case of antibodies whose mechanism of action involves blocking or antagonism but not killing of the cells bearing a target antigen. Reduction or elimination of effector function would be desirable in cases of autoimmune disease where one would block FcR activating receptors in effector cells (This type of function would be present in the host cells). In general increased effector function would be directed to tumor and foreign cells. [001631 The Fe variants of the present invention may be combined with other Fe modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Fe variant of the invention with other Fe modifications to provide additive, synergistic, or novel properties in antibodies or Fe fusions. Preferably the Pc variants of the invention enhance the phenotype of the modification with which they are combined. For example, if an Fe variant of the invention is combined with a mutant known to bind PeRlIlA with a higher affinity than a comparable molecule comprising a wild type Pc region; the combination with a mutant of the invention results in a greater fold enhancement in PeRILIA affinity. [001641 In one embodiment, the Fe variants of the present invention may be combined with other known Pc variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et al., 1991, J. Immunol 147:2657-2662; Lund et aT, 1992, Mol Inimunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1 543; Hutchins et al., 1995, Proc Natl. Acad Sci U S A 92:11980-11984; Jefferis et al, 1995, Immunol Lett. 44:111-117; Lund etal., 1995, Paseb J 9:115-119; Jefferis etal, 1996, Immunol Lett 54:101-104; Lund et al, 1996, J Immunol 157:49634969; Armour et aL, 1999, Eur .1 Immunol 29:2613-2624; Idusogie et al, 2000, J Irnmunol 164:41784184; Reddy et al, 2000, J Immunol 164:1925-1 933; Xu Ct aL, 2000, Cell Immunol 200:16-26; Idusogie et aT, 2001, J Immunol 166:2571-2575; Shields et aT., 2001, J Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Lett 82:57-65; Presta et al., 2002, Biochem Soc Trans 30:487-490); Us 5,624,821; US 5,885,573; Us 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety. (001651 In some embodiments, the Pc variants of the present invention are incorporated into an antibody or Fe fusion that comprises one or more engineered glycofornis, Le., a carbohydrate composition that is covalently attached to a molecule comprising an Fe region, wherein said carbohydrate composition differs chemically from that of a parent molecule comprising an Fe region. Engineered glycoforms may be useful for a variety of purposes, including but not limited to enhancing or reducing effector ue~dcjl~jcoforins may be generated by any method known to one skilled in the art, br example by using engineered or variant expression strains, by co-expression with one or more enzymes, for example DI N-acetylglucosaniinyltransferase III (GnTII 1), by expressing a molecule comprising an Fe region in various organisms or cell lines from various organisms, or by modifying carbohydrate(s) after the molecule comprising Pc region has been expressed. Methods for generating engineered glycoforms are known in the art, and include but are not limited to those described in Umana et al, 1999, Nat. Biotechnol 17:176-180; Davies et aT., 20017 Biotechnol Bioeng 74:288-294; Shields et at, 2002, J Biol Chem 277:26733-26740; Shinkawa et aL, 2003, J Biol Chem 278:3466-3473) US 6,602,684; USSN 10/277,370; USSN 10/113,929; POT WO 00/61739A1; PCT WO 0l/292246A1; POT WO 02/311140A1; POT WO 02/30954A1; PotillegentW technology (Biowa, Inc. Princeton, NJ); GlycoMAbTh glycosylation engineering technology (GLYCART biotechnology AG, Zurich, Switzerland); each of which is incorporated herein by reference in its entirety. See, e.g., WO 00061739; EA01229125; US 20030115614; Okazaki et al., 2004, JMB, 336: 1239-49 each of which is incorporated herein by reference in its entirety. [001661 The Fe variants of the present invention may be optimized for a variety of properties. Properties that may be optimized include but are not limited to enhanced or reduced affinity for an PeR, enhanced or reduced effector function. In a preferred embodiment, the Fe variants of the present invention are optimized to possess enhanced affinity for a human activating PeR, preferably PeR, FcRIIA, FcRile, PcRJIIA, and PcRIIIB, most preferably PcRIIIA. In an alternate preferred embodiment, the Fe variants are optimized to possess reduced affinity for the human inhibitory receptor PeRflB. These preferred embodiments are anticipated to provide antibodies and Fe fusions with enhanced therapeutic properties in humans, for example enhanced effector function and greater anti¬cancer potency as described and exemplified herein. These preferred embodiments are anticipated to provide antibodies and Pc fusions with enhanced tumor elimination in mouse xenograft tumor models. [001671 in an alternate embodiment the Fe variants of the present invention are optimized to have reduced affinity for a human PcR. including but not limited to PeRI, PeRIIA, FcRIIB, FcRile, FcRflIA, and PcRflIfl. These embodiments are anticipated to provide antibodies and Fe fusions with enhanced therapeutic properties in humans,for example reduced effector function and reduced toxicity. [00168] In alternate embodiments the Pc variants of the present invention possess enhanced or reduced affinity for FcRs from non-human organisms, including but not its, and monkeys. Pc variants that are optimized for binding to a non-human PeR may find use in experimentation. For example, mouse models are available for a variety of diseases that enable testing of properties such as efficacy, toxicity, and pharinacokinetics for a given drug candidate. As is known in the art, cancer cells can be grafted or injected into mice to mimic a human cancer, a process referred to as xenografting. Testing of antibodies or Fe fusions that comprise Pc variants that are optimized for one or more mouse PeRs, may provide valuable information with regard to the efficacy of the antibody or Fe fusion, its mechanism of action, and the like. [001691 While it is preferred to alter binding to an FcR, the instant invention further contemplates Fe variants with altered binding affinity to the neonatal receptor (FeRn). Although not intending to be bound by a particular mechanism of action, Pc region variants with improved affinity for FeRn are anticipated to have longer serum half-lives, and such molecules will have useful applications in methods of treating mammals where long half-life of the administered polypeptide is desired, e.g, to treat a chronic disease or disorder. Although not intending to be bound by a particular mechanism of action, Pc region variants with decreased FeRn binding affinity, on the contrary, are expected to have shorter half-lives, and such molecules may, for example, be administered to a mammal where a shortened circulation time may be advantageous, e.g., for in vivo diagnostic imaging or for polypeptides which have toxic side effects when left circulating in the blood stream for extended periods. Fe region variants with decreased FeRn binding affinity are anticipated to be less likely to cross the placenta, and thus may be utilized in the treatment of diseases or disorders in pregnant women. [0 0170] In other embodiments, these variants may be combined with other known Fe modifications with altered FeRn affinity such as those disclosed in International Publication Nos. WO 98/23289; and WO 97/34631; and U.S. Patent No. 6,277,375, each of which is incorporated herein by reference in its entirety. [001711 The invention encompasses any other method known in the art for generating antibodies having an increased half-life in vivo, for example, by introducing one or more amino acid modifications (I.e., substitutions, insertions or deletions) into an IgO constant domain, or FeRn binding fragment thereof (preferably a Fe or hinge-Fe domain fragment). See, e.g., International Publication Nos. WO 98/23289; and WO 97/3463 1; and U.S. Patent No. 6,277,375, each of which is incorporated herein by reference in its entirety to be used in combination with the Pc variants of the invention. Further, antibodies of the invention can be conjugated to albumin in order to make the antibody or antibody fragment more stable in vivo or have a longer half-life in vivo. The techniques well-known in the art, see, e.g., WO 93/15199, Wa 93/15200, and WO 01/77137, and European Patent No. EP 413,622, all of which are incorporated herein by reference in their entirety. [00 172~ The variant(s) described herein may be subjected to further modifications, often times depending on the intended use of the variant. Such modifications may involve further alteration of the amino acid sequence (substitution, insertion and/or deletion of amino acid residues), fusion to heterologous polypeptide(s) and/or covalent modifications. Such further modifications may be made prior to, simultaneously with, or following, the amino acid modification(s) disclosed herein which results in altered properties such as an alteration of Fe receptor binding and/or ADCC activity. [00173] Alternatively or additionally, the invention encompasses combining the amino acid modifications disclosed herein with one or more further amino acid modifications that alter Clq binding and/or complement dependent cytoxicity function of the Pc region as determined in vitro and/or in vivo. Preferably, the starting molecule of particular interest herein is usually one that binds to Clq and displays complement dependent cytotoxicity (CDC). The further amino acid substitutions described herein will generally serve to alter the ability of the starting molecule to bind to Clq and/or modif~r its complement dependent cytotoxicity function, e.g., to reduce and preferably abolish these effector functions. In other embodiments molecules comprising substitutions at one or more of the described positions with improved Clq binding and/or complement dependent cytotoxicity (CDC) function are contemplated herein. For example, the starting molecule may be unable to bind Clq and/or mediate CDC and may be modified according to the teachings herein such that it acquires these further effector functions. Moreover, molecules with preexisting Clq binding activity, optionally further having the ability to mediate CDC may be modified such that one or both of these activities are altered, e.g., enhanced. In some embodiments, the invention encompasses variant Pc regions with altered CDC activity without any alteration in Clq binding. In yet other embodiments, the invention encompasses variant Fe regions with altered CDC activity and altered Cl q binding. [00174] To generate an Pc region with altered Clq binding and/or complement dependent cytotoxicity (CDC) function, the amino acid positions to be modified are generally selected from positions 270, 322,326, 327, 329,331, 333, and 334, where the numbering of the residues in an IgG heavy chain is that of the EU index as in Kabat et aT., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (199). These amino acidmodiflcations may be combined with one or more Fe modifications disclosed herein to provide a synergistic or and/or CDC activity. In other embodiments, the invention encompasses Pc variants with altered Clq binding and/or complement dependent cytotoxicity (CDC) function comprising an amino acid substitRtion at position 396 with leucine and at position 255 with leucine; or an amino acid substitution at position 396 with leucine and at position 419 with histidine; an amino acid substitution at position 396 with leucine and at position 370 with glutamic acid; an amino acid substitution at position 396 with leucine and at position 240 with alanine; an amino acid substitution at position 396 with leucine and at position 392 with threonine; an amino acid substitution at position 247 with leucine and at position 421 with lysine. The invention encompasses any known modification of the Fe region which alters CIq binding and/or complement dependent cytotoxicity (ODO) function such as those disclosed in Idusogie et al., 2001, J. Immunol. 166(4) 2571-5; Idusogie et al., J. Immunol. 2000 164(8): 4178-4184; each of which is incorporated herein by reference in its entirety. 100175] As disclosed above, the invention encompasses an Fe region with altered effector function, e.g., modified Clq binding and/or PcR binding and thereby altered CDC activity and/or ADOC activity. In specific embodiments, the invention encompasses variant Fe regions with improved Clq binding and improved FcRilI binding; e.g. having both improved ADCC activity and improved CDC activity. In alternative embodiments, the invention encompasses a variant Fe region with reduced CDC activity and/or reduced ADCC activity. In other embodiments, one may increase only one of these activities, and optionally also reduce the other activity, e.g. to generate an Fe region variant with improved ADCC activity, but reduced CDC activity and vice versa. A. MUTANTS Jf 7TH ENHANCED ALTERED AFFINITIES FOR FcyRIIIA and/or FcyPJIA [00176] The invention encompasses molecules comprising a variant Fe region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, wherein such modifications alter the affinity of the variant Fe region for an activating FcR In some embodiments, molecules of the invention comprise a variant Pc region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fe region for FcRHIA and/or PcRJIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Pc region. In another specific embodiment, molecules of the invention comprise a variant Fe region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fe region for FcyRIILA and/or FOyRILA by greater than 2 fold, relative to a comparable molecule comprising a wild-type sn,bediments of the invention the one or more amino acid modifications increase the affinity of the variant Pc region for FcRIHA and/or PeyRIIA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Fe region. In yet other embodiments of the invention the one or more amino acid modifications decrease the affinity of the variant Fe region for PcRIIIA and/or PeRILA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Pc region. Such fold increases are preferably determined by an ELISA or surface plasmon resonance assays. In a specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at any one of positions 329,331, or 322 with any amino acid. In certain embodiments, the one or more amino acid modifications do not include or are not solely a substitution with any one of alanine at positions 256,290,298, 312, 333, 334, 359, 360, or 430; with lysine at position 330; with threonine at position 339; with methionine at position 320; with serine, asparagme, aspartic acid, or glutamic acid at position 326 with glutamine, glutamic acid, methionine, histidine, valine, or leucine at position 334. In another specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at any of positions 280,290, 300,294, or 295. In another more specific embodiment, the one or more amino acid modifications do not include or are not solely a substitution at position 300 with leucine or isoleucine; at position 295 with lysine; at position 294 with asparagine; at position 298 with valine; aspartic acid proline, aspargine, or valine; at position 280 with histidine, glutamine or tyrosine; at position 290 with seine, glycine, theonine or tyrosine. [001771 In another specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIA with a greater affinity than a comparable molecule comprising the wild-type Pc region binds PeyRILA, provided that said variant Fe region does not have an alanine at any of positions 256,290, 326,255,258, 267,272,276, 280,283,285, 286, 331, 337, 268, 272, or 430; an asparagine at position 268; a giutamine at position 272; a glutamine, seine, or aspartic acid at position 286; a seine at position 290; a methionine, glutamine, glutamic acid, or arginine at position 320; a glutamic acid at position3 22; a serine, glutamic acid, or aspartic acid at position 326; a lysine at position 330; a glutamine at position 335; or a methionine at position 301. In a specific embodiment, molecules of the invention comprise a variant Fe region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modificitions increase the affinity of the variant Fe region for PeRIIA by at least 2-fold, relative to a comparable molecule comprising a wild-type Fe embodiment, molecules of the invention comprise a variant Fe region, having one or more amino acid modifications (e.g., substitutions) in one or more regions, which modifications increase the affinity of the variant Fe region for FcRiIA by greater than 2 fold, relative to a comparable molecule comprising a wild-type Fe region. In other embodiments of the invention the one or more amino acid modifications increase the affinity of the variant Fe region for PeRUA by at least 3-fold, 4-fold, 5-fold, 6-fold, 8-fold, or 10-fold relative to a comparable molecule comprising a wild-type Fe region [00178] In a specific embodiment, the invention encompasses molecules, preferably polypeptides, and more preferably immunoglobulins (e.g., antibodies), comprising a variant Pc region, having one or more amino acid modifications (e.g., substitutions but also include insertions or deletions), which modifications increase the affinity of the variant Fe region for PeRiIlA and/or PeRILA by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 150%, and at least 200%, relative to a comparable molecule comprising a wild-type Pc region. (00179] In a specific embodiment, the one or more amino acid modifications which increase the affinity of the variant Fe region for one or more activating PeRs comprise a substitution at position 347 with bistidine, and at position 339 with valine; or a substitution at position 425 with isoleucine and at position 215 with phenylalanine; or a substitution at position 408 with isoleucine, at position 215 with isoleucine, and at position 125 with leucine; or a substitution at position 385 with glutamic acid and at position 247 with histidine; or a substitution at position 348 with methionine, at position 334 with asparagine, at position 275 with isoleucine, at position 202 with methionine, and at position 147 with threonine; or a substitution at position 275 with isoleucine, at position 334 with asparagine, and at position 348 with methionine; or a substitution at position 279 with leucine and at position 395 with seine; or a substitution at position 246 with threonine and at position 319 with phenylalanine; or a substitution at position 243 with isoleucine and at position 379 with leucine; or a substitution at position 243 with leucine, at position 255 with leucine and at position 318 with lysine; or a substitution at position 334 with glutamie acid, at position 359 with asparagine, and at position 366 with seine; or a substitution at position 288 with methionine and at position 334 with glutamic acid, or a substitution at position 334 with glutaniic acid and at position 380 with aspartic acid; or a substitution at position 256 with serine, at position 305 with isoleucine, at position 334 with glutamic acid and at position 390 with seine; or a substitution at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine, at position 394 with methionine, and at position 424 with leucine; or a substitution at position 233 with aspartic acid and at position 334 vra aubstitution at position 334 with glutamic acid, at position 359 with asparagme, at position 366 with seine, and at position 386 with arginine; or a substitution at position 246 with threonineand at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine; or a substitution at position 244 with histidine, at positon 358 with methionine, at position 379 with methionine, at position 384 with lysine and at position 397 with methionine; or a substitution at position 217 with serine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 247 with leucine, at position 253 with asparagine, and at position 334 with asparagine; or a substitution at position 246 with isoleucine, and at position 334 with asparagine; or a substitution at position 320 with glutamic acid and at position 326 with glutamic acid; or a substitution at position 375 with cy~teine and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 234 with leucine, at position 292 with proline, and at position 305 with isoleucine; or a substitution at position 234 with leucine and at position 292 with proline; or a substitution at position 234 with leucine. Examples of other amino acid substitutions that results in an enhanced affinity for PeyRlilA in vitro are disclosed below and summarized in Table 5. [00180] The invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 243 with isoleucine and at position 379 with leucine, such that said molecule binds PeRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Pc region binds FcRILIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine, such that said molecule binds FcRIIIA with about a 5 fold higher affinity than a comparable molecule comprising the wild type Fe region binds PeRflIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 243 with leucine and at position 255 with leucine such mnoleeul~ bindsPeRfllA with about a 1 fold higher affinity than a comparable molecule comprising the wild type Pc region binds FcRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Fe region comprises a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine, such that said molecule binds PcRILIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Pc region binds FcRflIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Pc region comprises a substitution at position 288 with methionine and at position 334 with glutamic acid, such that said molecule binds FcRflIA with about a 3 fold higher affinity than a comparable molecule comprising the wild type Fe region binds PeyRIILA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Pc region comprises a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid, such that said molecule binds PeyRILIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Fe region binds FcRIHA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Pc region comprises a substitution at position 315 with isoleucine, at position 379 with methionine, and at position 399 with glutainic acid, such that said molecule binds FcRIIIA with about a 1 fold higher affinity than a comparable molecule comprising the wild type Fe region binds FcRIHA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine, such that said molecule binds FcRILIA with about a 2.5 fold higher affinity than a comparable molecule comprising the wild type Fe region binds PcRflIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 247 with leucine, and at position 421 with lysine, such that said molecule binds FcRflIA with about a 3 fold higher affinity than a comparable molecule comprising the wild type Fe region binds FcRILIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 392 with threonine and at position 396 with leucine such that said A with about a 4.5 fold higher affinity than a comparable molecule comprising the wild type Pc region binds PcRflIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Fe region comprises a substitution at position 293 with valine, at position 295 with glutamic acid, and at position 327 with threonine, such that said molecule binds FcRIIIA with about a 1.5 fold higher affinity than a comparable molecule comprising the wild type Pc region binds PeyRIIIA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Fe region, wherein said variant Fe region comprises a substitution at position 268 with asparagine and at position 396 with leucine, such that said molecule binds PeyRIIIA with about a 2 fold higher affinity than a comparable molecule comprising the wild type Fe region binds FcRIHA, as determined by an ELISA assay. In a specific embodiment, the invention encompasses a molecule comprising a variant Pc region, wherein said variant Fe region comprises a substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine, such that said molecule binds FcRILIA with about a 2 fold higher affinity than a comparable molecule comprising the wild type Fe region binds PeRlIIA, as determined by an ELISA assay. [00181] In a specific embodiment, the invention encompasses an isolated polypeptide comprising a vaxiant Fe region, wherein said variant Fe region comprises at least one amino add modification relative to a wild-type Pc region, such that said polypeptide specifically binds FcRIilA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 396 with histidine. In a specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PcRflIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 248 with methionine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeyRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 392 with arginine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 315 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 132 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 162 with valine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide com~3rising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid mQdiflcation comprises si~bstitution at position 379 with methionine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 219 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FoRILIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 282 with methionine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said A~pries at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRflIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 401 with valine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PoRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 222 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 334 with glutamic acid. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 377 with phenylalaine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRiIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 334 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 247 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 326 with glutamie acid. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said ~i4~regiQnaCQ~pXes at least one amino acid modification relative to a wild-type ic region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 372 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 224 with leucine. [00182] The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 275 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 398 with valine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeRIIlA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 334 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeR.ITIA with a greater affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 400 with proline. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PcRflIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 407 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant whrein and.Variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 372 with tyrosine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIIA with a similar affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 366 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds FcRflIA with a reduced affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 414 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRifiA with a reduced affinity than a comparable polypeptide cqmprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 225 with serine. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds FcRIIIA with a reduced aflinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 377 with asparagine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FoRflIA with a greater affinity than a comparable polypeptide comprising the wild-type Pc region, wherein said at least one amino acid modification comprises substitution at position 243 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 292 with proline. The invention encompasses an isolated polypeptide comprising a variant Fe Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 300 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds Pci RIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Pc region. wherein said at least one amino acid modification comprises substitution at position 305 with isoleucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PcR,ILIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIIA with a greater affinity than a comparable polypeptide comprising the wild-type Fe region, wherein said at least one amino acid modification comprises substitution at position 273 with phenylalanine. [00183] In a specific embodiment, the invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, such that said polypeptide specifically binds PeRIIIA with about a 2 fold greater affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 379 with niethionine. In another specific embodiment, the inv~ntion encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRILIA with about a 1.5 fold greater affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification Qomprises substitution at position 248 with methionine. [00184] In some embodiments, the molecules of the invention have an altered afiintiy for PeyRIIIA andlor PeRIIA as determined using in vitro assays (biochemical or immunological based assays) known in the art for determining Fe-FoR interactions, Le., speeifle'bindingir&f am Fiegion to an PeR including but not limited to ELISA assay, surface plasmon resonance assay, immunoprecipitation assays (See Section 5.2.5.1). Preferably, the binding properties of these molecules with altered affinities for activating PeyR receptors are also correlated to their activity as determined by in vitro functional assays for determining one or more FcR mediator effeetor cell functions (See Section 5.2.7), e.g., molecules with variant Fe regions with enhanced affinity for PcRIIIA have an enhanced ADCC activity. In most preferred embodiments, the molecules of the invention that have an altered binding property for an activating Fe receptor, e.g., PeRIIIA in an in vitro assay also have an altered binding property m in vivo models (such as those described and disclosed herein). However, the present invention does not exclude molecules of the invention that do not exhibit an altered PeR binding in in vitro based assays but do exhibit the desired phenotype in vivo. B. MUTANTS WITH ENHANCED AFFINITY FOR FcRIJIA AND RED UCED OR NO AFFINITY FOR FcyRJIB (00185] In a specific embodiment, the molecules of the invention comprise a variant Pc region, having one or more amino acid modifications (i.e., substitutions) in one or more regions, which one or more modifications increase the affinity of the variant Fe region for PeRIHA and decreases the affinity of the variant Fe region for PeRIIB, relative to a comparable molecule comprising a wild-type Pc region which binds PeRIilA and FcRIiB with wild-type affinity. In a certain embodiment, the one or more amino acid modifications do not include or are not solely a substitution with alanine at any of positions 256,298, 333, 334, 280,290,294,298, or 296; or a substitution at position 298 with asparagine, valine, aspartic acid, or praline; or a substit~ition 290 with seine. In certain amino embodiments, the one or more amino acid modifications increases the affinity of the variant Fe region for PeRIIIA by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at leat 400% and decreases the affinity of the variant Fe region for PeRIIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 990/o, at least 100%, at least 200%, at least 300%, at leat 400%. [00186] In a specific embodiment, the molecule of the invention comprising a variant Fe region with an enhanced affinity for FcRIIIA and a lowered affinity or no affinity for PoRIIB, as determined based on an BLISA assay and/or an ADCC based assay using eh-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Fe region comprises a substitution at position 275 with isoleucine, at position 334 with asparagine, and at position 348 with methionine; or a substitution at ,with Irticin~ and at position 395 with seine; or a substitution at position 246 with threonine and at position 319 with phenylalanine; or a substitution at position 243 with leucine, at position 255 with leucine, and at position 318 with lysine; or a substitution at position 334 with glutamic acid, at position 359 with asparagine and at position 366 with seine; or a substitution at position 334 with glutamic acid and at position 380 with aspartic acid; or a substitution at position 256 with serine, at position 305 with isoleucine, at position 334 with glutamic acid, and at position 390 with seine; or a substitution at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine, at position 394 with methionine and at position 424 with leucine; or a substitution at position 233 with aspartic acid and at position 334 with glutamic acid; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, at position 366 with serine and at position 386 with arginine; or a substitution at position 312 with glutamic acid, at position 327 with asparagine, and at position 378 with seine; or a substitution at position 288 with asparagine and at position 326 with asparagine; or a substitution at position 247 with leucine and at position 421 with lysine; or a substitution at position 298 with asparagine and at position 381 with arginine; or a substitution at position 280 with glutamic acid, at position 354 with phenylalanine, at position 431 with aspartic acid, and at position 441 with isoleucine; or a substitution at position 255 with glutamine and at position 326 with glutamic acid; or a substitution at position 218 with arginine, at position 281 with aspartic acid and at position 385 with arginine; or a substitution at position 247 with leucine, at position 330 with threonine and at position 440 with glycine; or a substitution at position 284 with alanine and at position 372 with leucine; or a substitution at position 335 with asparagine, as position 387 with serine and at position 435 with glutamine; or a substitution at position 247 with leucine, at position 431 with valine and at position 442 with phenylalanine; or a substitution at position 243 with leucine, at position 292 with proline, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 leucine, at position 292 with proline, and at position 305 with isoleucine; or a substitution at position 292 with proline, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 292 with proline; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine; or a substitution at position 243 with leucine. [00187] In a specific embodiment, the molecule of the invention comprising a variant Fe region with an enhanced affinity for FcRIIIA and a lowered affinity or no affinity for FcRflB as determined based on an ELISA assay and/or an ADCC based assay using ch-4- Fe region comprises a substitution at position 379 with methionine; at position 219 with tyrosine; at position 282 with methionine; at position 401 with valine; at position 222 with asparagine; at position 334 with isoleucine; at position 334 with glutamic acid; at position 275 with tyrosine; at position 398 with valine. In yet another specific embodiment, the molecule of the invention comprising a variant Fe region with an enhanced affinity for PeyRIJIA and a lowered affinity or no affinity for PeTRUB as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Pc region comprises a substitution at position 243 with leucine; at position 292 with proline; and at position 300 with leucine. [00188] The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIlB with about a 3 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 288 with asparagine, at position 330 with serine, and at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PcRIIB with about a 10-15 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamie acid. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIB with about a 10 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 315 with isoleucine, at position 379 with methionine, and at position 399 with giutamic acid. The invention encompasses an isolated polypeptide comprising a variant Pc region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIB with about a 7 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 243 with isoleucine, at position 379 with leucine, and at . The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIB with about a 3 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 392 with threonine and at position 396 with leucine. The invention encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds PeRIIB with about a 5 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 268 with asparagine and at position 396 with leucine. The invention also encompasses an isolated polypeptide comprising a variant Fe region, wherein said variant Pc region comprises at least one amino acid modification relative to a wild-type Fe region, such that said polypeptide specifically binds FcRIIB with about a 2 fold lower affinity than a comparable polypeptide comprising the wild-type Fe region as determined by an ELISA assay, wherein said at least one amino acid modification comprises substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine. MUTANTS WITH ENHANCED AFFINITY TO FcvRIIIA AND FcrPJIB [00 189] The invention encompasses molecules comprising variant Fe regions, having one or more amino acid modiflcatiqns, which modifications increase the affinity of the variant Fe region for FcRIIIA and PeyRIIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at leat 400% and decreases the affinity of the variant Fe region for PeyRJIB by at least 65%, at least 70%, at least 75%, at least 85%, at least 90%, at least 95%, at least 99%, at least 100%, at least 200%, at least 300%, at leat 400%. In a specific embodiment, the molecule of the invention comprising a variant Fe region with an enhanced affinity for PcyRIIIA and an enhanced affinity for PeyRIIB (as determined based on an ELISA assay and/or an ADCC based assay using ch-4-4-20 antibody, or a surface plasmon resonance assay using a chimeric 4D5 antibody, carrying the variant Fe region as described herein) comprises a substitution at position 415 with isoleucine and at position 251 with phenylalanine; or a substitution at positon 399 with glutamic acid, at position 292 with leucine, and at position 185 with methionine; or a substitution at position 408 with with isoleucine, and at position 125 with leucine; or a substitution at position 385 with glutamic acid and at position 247 with histidine; or a substitution at position 348 with methionine, at position 334 with asparagine, at position 275 with isoleucine, at position 202 with methionine and at position 147 with threonine; or a substitution at position 246 with threonine and at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 288 with asparagine, at position 330 with seine and at position 396 with leucine; or a substitution at position 244 with histidine, at position 358 with methionine, at position 379 with methionine, at position 384 with lysine and at position 397 with methionine; or a substitution at position 217 with serine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 247 with leucine, at position 253 with asparagine, and at position 334 with asparagine; or a substitution at position 246 with isoleucine and at position 334 with asparagine; or a substitution at postion 320 with glutamic acid and at position 326 with glutamic acid; or a substitution at positoion 375 with cysteine and at position 396 with leucine; or a substitution at position 343 with serine, at position 353 with leucine, at position 375 with isoleucine, at position 383 with asparagine; or a substitution at position 394 with methionine and at position 397 with methionine; or a substitution at position 216 with aspartic acid, at position 345 with lysine and at position 375 with isoleucine; or a substitution at position 288 with asparagine, at position 330 with seine, and at position 396 with leucine; or a substition at position 247 with leucine and at position 389 with glycine; or a substitution at position 222 with asparagine, at position 335 with asparagine, at position 370 with glutamic acid, at position 378 with valine and at position 394 with methionine; or a substitution at position 316 with aspartic acid, at position 378 with valine and at position 399 with glutamic acid; or a substitution at position 315 with isoleucine, at position 379 with methionine, and at position 394 with methionine; or a substitution at position 290 with threonine and at position 371 with aspartic acid; or a substitution at position 247 with leucine and at position 398 with glutamine; or a substitution at position 326 with glutamine; at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with seine; or a substitution at position 247 with leucine and at position 377 with phenylalanine; or a substitution at position 378 with valine, at position 390 with isoleucine and at position 422 with isoleucine; or a substitution at position 326 with glutamic acid and at position 385 with glutainic acid; or a substitution at position 282 with glutamic acid, at position 369 with isoleucine and at position 406 with phenylalanine; or a substitution at position 397 with methionine; at position 411 with alanine and at position 415 with asparagine; or a substitution at position 223 with ~tpoeiti0w~6 with serine and at position 406 with phenylalanine; or a substitution at position 298 with asparagine and at position 407 with arginine; or a substitution at position 246 with arginine, at position 298 with asparagine, and at position 377 with phenylalanine; or a substitution at position 235 with proline, at position 382 with methionine, at position 304 with glycine, at position 305 with isoleucine, and at position 323 with isoleucine; or a substitution at position 247 with leucine, at position 313 with arginne, and at position 388 with glycine; or a substitution at position 221 with tyrosine, at position 252 with isoleucine, at position 330 with glycine, at position 339 with threonine, at position 359 with asparagine, at position 422 with isoleucine, and at position 433 with leucine; or a substitution at position 258 with aspartic acid, and at position 384 with lysine; or a substitution at position 241 with leucine and at position 258 with glycine; or a substitution at position 370 with asparagine and at position 440 with asparagine; or a substitution at position 317 with asparagine and a deletion at position 423; or a substitution at position 243 with isoleucine, at position 379 with leucine and at position 420 with valine; or a substitution at position 227 with seine and at position 290 with glutamic acid; or a substitution at position 231 with valine, at position 386 with histidine, and at position 412 with methionine; or a substitution at position 215 with proline, at position 274 with asparagine, at position 287 with glycine, at position 334 with asparagine, at positon 365 with valine and at position 396 with leucine; or a substitution at position 293 with valine, at position 295 with glutamic acid and at position 327 with threonine; or k substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine; or a substitution at position 392 with threonine and at position 396 with leucine; at a substitution at position 268 with asparagine and at position 396 with leucine; or a substitution at position 290 with threonine, at position 390 with isoleucine, and at position 396 with leucine; or a substitution at position 326 with isoleucine and at position 396 with leucine; or a substitution at position 268 with aspartic acid and at position 396 with leucine; or a substitution at position 210 with methionine and at position 396 with leucine; or a substitution at position 358 with proline and at position 396 with leucine; or a substitution at position 288 with arginine, at position 307 with alanine, at position 344 with glutamic acid, and at position 396 with leucine; or a substitution at position 273 with isoleucine, at position 326 with glutamic acid, at position 328 with isoleucine and at position 396 with leucine; or a substitution at position 326 with isoleucine, at position 408 with asparagine and at position 396 with leucine; or a substitution at position 334 with asparagine and at position 396 with leucine; or a substitution at position 379 with methionine and at position 396 with leucine; or a substitution at position 227 with serine and at position 396 with leucine; or a ~bt~Iitiosit~a ~17 with serine and at position 396 with leucine; or a substitution at position 261 with asparagine, at position 210 with methionine and at position 396 with leucine; or a substitution at position 419 with histidine and at position 396 with leucine; or a substitution at position 370 woth glutamic acid and at position 396 with leucine; or a substitution at position 242 with phenylalanine and at position 396 with leucine; or a substitution at position 255 with leucine and at position 396 with leucine; or a substitution at position 240 with alanine and at position 396 with leucine; or a substitution at position 250 with seine and at position 396 with leucine; or a substitution at position 247 with seine and at position 396 with leucine; or a substitution at position 410 with histidine and at position 396 with leucine; or a substitution at position 419 with leucine and at position 396 with leucine; or a substitution at position 427 with alanine and at position 396 with leucine; or a substitution at position 258 with aspartic acid and at position 396 with leucine; or a substitution at position 384 with lysine and at position 396 with leucine; or a substitution at position 323 with isoleucine and at position 396 with leucine; or a substitution at position 244 with histidine and at position 396 with leucine; or a substitution at position 305 with leucine and at position 396 with leucine; or a substitution at position 400 with phenylalanine and at position 396 with leucine; or a substitution at position 303 with isoleucine and at position 396 with leucine; or a si.ibstitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with seine and at position 396 with leucine; or a substitution at position 290 with glutamic acid, at position 369 with alanine, at position 393 with alanine and at position 396 with leucine; or a substitution at position 210 with asparagine, at position 222 with isoleucine, at position 320 with methionine and at position 396 with leucine; or a substitution at position 217 with serine, at position 305 with isoleucine, at position 309 with leucine, at position 390 with histidine and at position 396 with leucine; or a substitution at position 246 with asparagine; at position 419 with arginine and at position 396 with leucine; or a substitution at position 217 with alanine, at position 359 with alanine and at position 396 with leucine; or a substitution at position 215 with isoleucine, at position 290 with valine and at position 396 with leucine; or a substitution at position 275 with leucine, at position 362 with histidine, at position 384 'with lysine and at position 396 with leucine; or a substitution at position 334 with asparagine; or a substitution at position 400 with proline; or a substitution at position 407 with isoleucine; or a substitution at position 372 with tyrosine; or a substitution at position 366 with asparagine; or a substitution at position 414 with asparagine; or a substitution at position 352 with leucine; or a substitution at position 225 with serine; or a substitution at position 377 with asparagine; or a substitution at position 248 with methionine; or a -ueq-¬ with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 396 with leucine; or at position 292 with proline, and at position 305 with isoleucine. D. MUTANTS THATDONOTBINDANYFcyR (001901 In some embodiments, the invention encompasses molecules comprising a variant Fe region, wherein said variant Fe region comprises at least one amino acid modification relative to a wild-type Pc region, which variant Pc region does not bind any PeyR, as determined by standard assays known in the art and disclosed herein, relative to a comparable molecule comprising the wild type Pc region. In a specific emobodiment, the one or more amino acid modifications which abolish binding to all FcRs comprise a substitution at position 232 with serine and at position 304 with glycine; or a substitution at position 269 with lysine, at position 290 with asparagine, at position 311 with arginine, and at position 433 with tyrosine; or a substitution at position 252 with leucine; or a substitution at position 216 with aspartic acid, at position 334 with arginine, and at position 375 with isoleucine; or a substitution at position 247 with leucine and at position 406 with phenylalanine, or a substitution at position 335 with asparagine, at position 387 with seine, and at position 435 with glutamine; or a substitution at position 334 with glutamic acid, at position 380 with aspartic acid, and at position 446 with valine; or a substitution at position ~03 with isoleucine, at position 369 with phenylalanine, and at position 428 with leucine; or a substitution at position 251 with phenylalanine and at position 372 with leucine; or a substitution at position 246 with glutamic acid, at position 284 with methionine and at postion 308 with alanine; or a substitution at position 399 with glutamic acid and at position 402 with aspartic acid; or a substitution at position 399 with glutamic acid and at position 428 with leucine. D. MUTANTS WITHALTERED Fe yR-MEDIA TED EFFECTOR FUNCTIONS [00191] The invention encompasses immunoglobulin comprising Fe variants with altered effector functions. In some embodiments, immunoglobulins comprising Pc variants mediate effector function more effectively in the presence of effeetor cells as determined using assays known in the art and exemplified herein. In other embodiments, immunoglobulins comprising Fe variants mediate effeetor function less effectively in the presence of effector cells as determined using assays known in the art and exempli~ed the Fe variants of the invention may be combined with other known Fe modifications that alter effector function, such that the combination has an additive, synergistic effect The Fe variants of the invention have altered effector function in vitro and/or in vivo. [001921 In a specific embodiment, the inimunoglobulins of the invention with enhanced affinity for FcRLILA and/or PeRiIA have an enhanced PeyR-mediated effector function as determined using ADCC activity assays disclosed herein. Examples of effeetor functions that could be mediated by the molecules of the invention include, but are not limited to, Clq binding, complement-dependent cytotoxicity, antibody-dependent cell mediate cytotoxicity (ADCC), phagocytosis, etc. The effector functions of the molecules of the invention can be assayed using standard methods known in the art, examples of which are disclosed in Section 5.2.6. In a specific embodiment, the immunoglobulins of the invention comprising a variant Fe region with enhanced affinity for FcRflIA and/or PeRIIA mediate antibody dependent cell mediated cytotoxicity (ADOC) 2- fold more effectively, than an imniunoglobulin comprising a wild-type Pc region. In other embodiments, the immunoglobulins of the invention comprising a variant Fe region with enhanced affinity for PeyRflIA and/or PeyRIIA mediate antibody dependent cell mediated cytotoxicity (ADCC) at least 4- fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 1 04-fold, at least 105-fold more effectively, than an immunoglobulin comprising a wild-type Pc region. In another specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcRJIIA and/or FcRIIA have altered Cl q binding activity. In some embodiments, the immunoglobulins of the invention with enhanced affinity for PeRIIIA and/or PeRLIA have at least 2-fold, at least 4- fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 104-fold, at least 105-fold higher Clq binding activity than an ixnmunoglobulin comprising a wild-type Fe region. In yet another specific embodiment, the immunogiobulins of the invention with enhanced affinity for FcRiIIA and/or PeyRIIA have altered complement dependent cytotoxicity. In yet another specific embodiment, the immunoglobulins of the invention with enhanced affinity for FcRIilA and/or PeRiIA have an enhanced complement dependent cytotoxicity than an inimunoglobulin comprising a wild-type Fe region. In some embodiments, the immunoglobulins of the invention with enhanced affinity for FcRUIA and/or FcRTIA have at least 2-fold, at least 4- fold, at least 8-fold, at least 10-fold, at least 100-fold, at least 1000-fold, at least 104-fold, at least 105-fold higher complement dependent cytotoxicity than an inimunoglobulin comprising a wild-type Fe region. mbodiments, iinmunoglobulins of the invention with enhanced affinity for PeRIiIA and/or PeRILA have enhanced phagocytosis activity relative to an ixnmunoglobulin comprising a wild-type Fe region, as determined by standard assays known to one skilled in the art or disclosed herein. In some embodiments, the immunoglobulins of the invention with enhanced affinity for PeRIIIA and/or PeRLIA have at least 2-fold, at least 4- fold, at least 8-fold, at least 10-fold higher phagocytosis activity relative to an immunoglobulin comprising a wild-type Fe region. [00194] In a specific embodiment, the invention encompasses an irnmunoglobulin comprising a variant Fe region with one or more amino acid modifications, with an enhanced affinity for PeRIIIA and/or PeRIIA such that the immunoglobulin has an enhanced effector function, e.g., antibody dependent cell mediated cytotoxicity, or phagocytosis. In a specific embodiment, the one or more amino acid modifications which increase the affinity of the variant Pc region for PeRIIIA and/or FcRIIA and increase the ADCC activity of the inimunoglobulin comprise a substitution at position 379 with methionine; or a substitution at position 243 with isoleucine and at position 379 with leucine; or a substitution at position 288 with asparagine, at position 330 with seine, and at position 396 with leucine; or a substitution at position 243 leucine and at position 255 with leucine; or a substitution at position 334 with glutamic acid, at position 359 with asparagine, and at position 366 with serine; or a substitution at position 288 with methionine and at position 334 with glutamic acid; or a si~ibstitution at position 334 with glutamic acid and at position 292 with leucine; or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid; or a substitution at position 315 with isole~icine, at position 379 with methionine, and at position 399 with glutamic acid; or a substitution at position 243 with isoleucine, at position 379 with leucine, and at position 420 with valine; or a substitution at position 247 with leucine and at position 421 with lysine; or a substitution at position 248 with methionine; or a substitution at position 392 with threonine and at position 396 with leucine; or a substitution at position 293 with valine, at position 295 with glutamic acid, and at position 327 with threonine; or a substitution at position 268 with asapragine and at position 396 with leucine; or a substitution at position 319 with phenylalanine, at position 352 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine. specific embodiment, the one or more amino acid modifications which increase the ADOC activity of the immunoglobulin is any of the mutations listed below, in table 7. TABLE 7. AMINO ACID MODIFICATION WHICH INCREASE ADCC (Table Removed) [00196] Alternatively or additionally, it may be useful to combine the above amino acid modifications or any other amino acid modifications disclosed herein with one or more further amino acid modifications that alter Clq binding and/or complement dependent cytoxicity function of the Fe region. The starting molecule of particular interest herein is usually one that binds to Cl q and displays complement dependent cytotoxicity (CDC). The further amino acid substitutions described herein will generally serve to alter the ability of the starting molecule to bind to Clq and/or modify its complement dependent cytotoxicity function, e.g., to reduce and preferably abolish these effector functions. However, molecules comprising substitutions at one or more of the described positions with improved Clq binding and/or complement dependent cytotoxicity (CDC) function are contemplated herein. For example, the starting molecule may be unable to bind Clq and/or mediate CDC and may be modified according to the teachings herein such that it acquires these further effeetor functions. Moreover, molecules with preexisting CIq binding activity, optionally further having the ability to mediate CDC may be modified such that one or both of these activities are enhanced. As.diseJe~ed above, one can design an Fe region with altered effector function, e.g., by modifying Clq binding and/or PcR binding and thereby changing CDC activity and/or ADCC activity. Por example, one can generate a variant Fe region with improved Clq binding and improved PeyRiII binding; e.g., having both improved ADCC activity and improved CDC activity. Alternatively, where one desires that effector function be reduced or ablated, one may engineer a variant Pc region with reduced CDC activity and/or reduced ADCC activity. In other embodiments, one may increase only one of these activities, and optionally also reduce the other activity, e.g., to generate an Fe region variant with improved ADCC activity, but reduced CDC activity and vice versa [00198] The invention encompasses specific variants of the Pc region that have been identified using the methods of the invention from a yeast library of mutants after 2nd-4th-round of sorting are listed in Table 8. Table S summarizes the various mutants that were identified using the methods of the invention. The mutants were assayed using an ELISA assay for determining binding to PeyRJIIA and PcyRIIB. The mutants were also tested in an ADCC assay, by cloning the Fe variants into a ch 4-4-20 antibody using methods disclosed and exemplified herein. Bolded items refer to experiments, in which the ch4-4-20 were purified prior the ADCC assay. The antibody concentration used was in the range 0.5 µg/mL - 1.0µg/mL. MUTATIONS IDENTIFIED IN THE Fc REGION (Table Removed) embodiments, the invention provides modu um±iuni.,gii.a~dlin molecules (e.g., antibodies) with variant Pc regions, having one or more amino acid modifications, which one or more amino acid modifications increase the affinity of the molecule for PcyRIIIA and/or PeyRHA. Such inimunoglobulins include IgG molecules that naturally contain PeyR binding regions (e.g., PeyRIIA and/or PeyRIB binding region), or inimunoglobulin derivatives that have been engineered to contain an PeR binding region (e.g., PcRUIA and/or PeRIIB binding region). The modified irnmunoglobulins of the invention include any immunoglobulin molecule that binds, preferably, immunospecifically, i.e., competes off non-specific binding as determined by immunoassays well known in the art for assaying specific antigen-antibody binding, an antigen and contains an FcR binding region (e.g., a FcRflIA and/or FcRIiB binding region). Such antibodies include, but are not limited to, polyclonal, monoclonal, bi-specific, multi-specific, human, humanized, chimeric antibodies, single chain antibodies, Fab fragments, P(ab')2 fragments, disulfide¬linked Pvs, and fragments containing either a VL or VII domain or even a complementary determining region (CDR) that specifically binds an antigen, in certain cases, engineered to contain or fused to an FcR binding region. [00200] In some embodiments, the molecules of the invention comprise portions of an Fe region. As used herein the term "portion of an Fe region" refers to fragments of the Pc region, preferably a portion with effector activity and/or FcR binding activity (or a comparable region of a mutant lacking such activity). The fragment of an Pc region may range in size from 5 amino acids to the entire Fe region minus one amino acids. The portion of an Pc region may be missing up to 10, up to 20, up to 30 amino acids from the N-terminus or C-terminus. [00201] The IgG molecules of the invention are preferably IgGi subclass of IgGs, but may also be any other IgG subclasses of given animals. For example, in humans, the IgG class includes IgGi, IgG2, IgG3, and IgG4; and mouse IgG includes IgGi, IgG2a, IgG2b, IgG2c and IgG3. [00202] The immunoglobulins (and other polypeptides used herein) may be from any animal origin including birds and mammals. Preferably, the antibodies are human, rodent (e.g., mouse and rat), donkey, sheep, rabbit, goat, guinea pig, camel, horse, or chicken. As used herein, "human" antibodies include antibodies having the amino acid sequence of a human imnmunoglobulin and include antibodies isolated from human immunoglobulin libraries or from animals transgenic for one or more human immunoglobulin and that do not express endogenous immunoglobulins, as described infra and, for example, in U.S. Patent No. 5,939,598 by Kucherlapati et aL the present invention may be monospecific, bispecitic, trispecific or of greater multispecificity. Multispecific antibodies may be specific for different epitopes of a polypeptide or may be specific for heterologous epitopes, such as a heterologous polypeptide or solid support material. See, e.g., PCT publications WO 93/17715; WO 92/08802; WO 91/00360; WO 92/05793; Tutt, et al., .1. Immunol., 147:60- 69, 1991; U.S. Patent Nos. 4,474,893; 4,714,681; 4,925,648; 5,573,920; 5,601,819; Kostelny et aL, J. Immunol., 148:1547-1553, 1992. [00204] Multispecific antibodies have binding specificities for at least two different antigens. While such molecules normally will only bind two antigens (i.e. bispecific antibodies, BsAbs), antibodies with additional specificities such as trispecific antibodies are encompassed by the instant invention. Examples of BsAbs include without limitation those with one arm directed against a tumor cell antigen and the other arm directed against a cytotoxic molecule. [00205] Methods for making bispeciflo antibodies are known in the art. Traditional production of full length bispecific antibodies is based on the coexpression of two immunoglobulin heavy chain-light chain pairs, where the two chains have different specifleities (Milistein et al., Nature, 305:537-539 (1983); which is incorporated herein by reference in its entirety). Because of the random assortment of immunogiobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of 10 different antibody molecules, of which only one has the correct bispecific structure. Purification of the correct molecule, which is usually done by affinity chromatography steps, is rather cumbersome, and the product yields are low. Similar procedures are disclosed in WO 93/08829, and in Traunecker et aL, EMBO J., 10:3655-3659 (1991). (00206] According to a different approach, antibody variable domains with the desired binding specificities (antibody-antigen combining sites) are fused to immunoglobulin constant domain sequences. The fusion preferably is with an inimunoglobulin heavy chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions. It is preferred to have the first heavy-chain constant region (CHI) containing the site necessary for light chain binding, present in at least one of the fusions. DNAs encoding the inimunoglobulin heavy chain fusions and, if desired, the inimunoglobulin light chain, are inserted into separate expression vectors, and are co¬transfected into a suitable host organism. This provides for great flexibility in adjusting the mutual proportions of the three polypeptide fragments in embodiments when unequal ratios of the three polypeptide chains used in the construction provide the optimum yields. It is, however, possible to insert the coding sequences for two or all three polypeptide chains in the expression of at least two polypeptid~ciiams in equal ratios results in high yields or when the ratios are of no particular significance. [00207] In a preferred embodiment of this approach, the bispecific antibodies are composed of a hybrid immunoglobulin heavy chain with a first binding specificity in one arm, and a hybrid immunoglobulin heavy chain-light chain pair (providing a second binding specificity) in the other arm. It was found that this asymmetric strueture facilitates the separation of the desired bispecific compound from unwanted immunoglobulin chain combinations, as the presence of an immunoglol~ulin light chain in only one half of the bispecific molecule provides for a facile way of separation. This approach is disclosed in WO 94/04690. For further details of generating bispecific antibodies see, for example, Suresh et ab, Methods in Enzymology, 121:210 (1986). Accqrding to another approach described in W096/2701 1, a pair of antibody molecules can be engineered to maximize the percentage of heterodimers which are recovered from recombinant cell culture. The preferred interface comprises at least a part of the CH3 domain of an antibody constant domain. In this method, one or more small amino acid side chains from the interface of the first antibody molecule are replaced with larger side chains (e.g. tyrosine or tryptophan). Compensatory "cavities" of identical or similar size to the large side chain(s) are created on the interface of the second antibody molecule by replacing large amino acid side chains with smaller ones (e.g. alanine or threonine). This provides a mechanism for increasing the yield of the heterodimer over other unwanted end-products such as homodimers. [00208] Bispecifle antibodies include cross-linked or "heteroconjugate" antibodies. For example, one of the antibodies in the heteroconjugate can be coupled to avidin, the other to biotin. Such antibodies have, for example, been proposed to target immune system cells to unwanted cells (U.S. Pat. No. 4,676,980), and for treatment of lilY infection (WO 9 1/00360, WO 92/200373, and EP 03089). Heteroconjugate antibodies may be made using any convenient cross-linking methods. Suitable cross-linking agents are well known in the art, and are disclosed in U.S. Pat. No. 4,676,980, along with a number of cross-linking techniques. [00209] Antibodies with more than two valencies are contemplated. For example, trispecific antibodies can be prepared. See, e.g., Tutt et al. J. Immunol. 147: 60(1991), which is incorporated herein by reference. [00210] The antibodies of the invention include derivatives that are otherwise modified, i.e., by the covalent attachment of any type of molecule to the antibody such that covalent attachment does not prevent the antibody from binding antigen and/or generating an anti-idiotypic response. For example, but not by way of limitation, the antibody Pdies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. [00211] For some uses, including in vivo use of antibodies in humans and in vitro detection assays, it may be preferable tQ use chimeric, humanized, or human antibodies. A chimeric antibody is a molecule in 'vitich different portions of the antibody are derived from different animal species, such as antibodies having a variable region derived from a murine nionoclonal antibody and a constant region derived from a human immunogiobulin. Methods for producing chimeric antibodies are known in the art. See e.g., Morrison, Science, 229:1202, 1985; Ol et at, BioTechniques, 4:214 1986; Gillies et at, J. bnmunol. Methods, 125:191-202, 1989; U.S. PatentNos. 5,807,715; 4,816,567; and 4,816,397, which are incorporated herein by reference in their entireties. Humanized antibodies are antibody molecules from non-human species that bind the desired antigen having one or more complementarity determining regions (CDRs) from the non-human species and framework regions and constant domains from a human inimunoglobulin molecule. Often, framework residues in the human framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. See, e.g., Queen eta!., U.S. Patent No. 5,585,089; Riechniana ef aL, Nature, 332:323,1988, which are incorporated herein by reference in their entireties. Antibodies can be humanized using a variety of techniques known in the art including, for example, CDR-grafting (B? 239,400; PCT publication WO 91/09967; U.S. Patent Nos. 5,225,539; 5,530,101 and 5,585,089), veneering or resurfacing (EP 592,106; EP 5 19,596; Padlan, Molecular Immunology, 28(4/5):489-498, 1991; Studnicka eta!., Protein Engineering, 7(6):805-8 14, 1994; Roguska eta)., Proc Nat). Acad. Scl. USA, 91:969-973, 1994), and chain shuffling (U.S. Patent No. 5,565,332), all of which are hereby incorporated by reference in their entireties. Humanized antibodies may be generated using any of the methods disclosed in U.S. Patent Nos. 5,693,762 (Protein Design Labs), 5,693,761, (Protein Design Labs) 5,585,089 (Protein Design Labs), 6,180,370 (Protein Design Labs), herein by reference in its entirety. 100212] Completely human antibodies are particularly desirable for therapeutic treatment of human patients. Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobulin sequences. See U.S. Patent Nos. 4,444,887 and 4,716,111; and PCT publications WO 98/46645; WO 98/50433; WO 98/24893; WO 98/1 6654; WO 96/34096; WO 96/33735; and WO 91/1 074], each of which is incorporated herein by reference in its entirety. [002131 Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. For an overview of this technology for producing human antibodies, see Lonberg and Huszar, mt. Rev. IminunoL, 13:65-93, 1995. For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., PCT publications WO 98/24893; WO 92/01047; WO 96/34096; WO 96/33735; European Patent No. 0 598 877; U.S. Patent Nos. 5,413,923; 5,625,126; 5,633,425; 5,569,825; 5,661,016; 5,545,806; 5,814,318; 5,885,793; 5,916,771; and 5,939,598, which are incorporated by reference herein in their entireties. In addition, companies such as Abgenix, Inc. (Freemont, CA), Medarex (NJ) and Qeupharm (San Jose, CA) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above. [002141 Completely human antibodies which recognize a selected epitope can be generated using a technique referred to as "guided selection." In this approach a selected non-human monoclonal antibody, e.g., a mouse antibody, is used to guide the selection of a completely human antibody recognizing the same epitope (Jespers et a!., Bioltechnology, 12:899-903, 1988). [002151 The invention encompasses engineering human or humanized therapeutic antibodies (e.g., tumor specific monoclonal antibodies) in the Fc region, by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue, which modification increases the affinity of the Fc region for FcRIilA and/or FcyRIIA. In another embodiment, the invention relates to engineering human or humanized therapeutic antibodies (e.g. tumor specific monoclonal antibodies) in the Fe region, by modification of at least one amino acid residue, which modification increases the affinity of the Fe region for FcyRflIA and/or FcyRI[A and further decreases the affinity of the Fe region for FcyRIIB. The engineered therapeutic antibodies may further have an enbanced effector activity, phagocytosis activity, etc., as deterixuneci by standard assays known to those skilled in the art. 1002161 In a specific embodiment, the invention encompasses engineering a humanized monoclonal antibody specific for Her2/neu protooncogene (e.g., Ab4D5 humanized antibody as disclosed in Carter etal., 1992, Proc. Nat!. Acad2 Sci. USA 89:4285-9) by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fe rgion for FcRIIIA and/or FcRITA. In another specific embodiment, modification of the humanized Her2/neu monoclonal antibody may also further decrease the affinity of the Fe region for FcRIIB. In yet another specific embodiment, the engineered humanized monoclonal antibodies specific for Her2/neu may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. [002171 In another specific embodiment, the invention encompasses engineering a mousehuman chimeric anti-CD2O monoclonal antibody, 2H7 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fe rgion for FcRIRA and/or FcyRflA. In another specific embodiment, modification of the anti-CD2O monoclonal antibody, 2H7 may also further decrease the affinity of the Fc region for FcRTIB. In yet another specific embodiment, the engineered anti-CD2O monoclonal antibody, 2H7 may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. [00218] In certain embodiments, the invention encompasses engineering an antibody (or chimeric, humanized or other engineered versions thereof), comprising the heavy chain variable domain and/or light chain variable domain of the monoclonal antibody produced by clone 2B6, 3H7, 8B5.4.3, 1D5, 2E1, 2H9, 2D1 1 or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (deposited at ATCC, 10801 University Boulevard, Manassas, VA 02209- 2011, all of which are incorporated herein by reference). In a specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable and/or light chain variable domains of 2B6, 3H7 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the CDRs of 2B6, 3H7 or 8B5.3.4. In another specific embodiment, the invention encompasses engineering a humanized antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO: 1, SEQ ID NO:2 or SEQ 112) NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO: 4, SEQ ID NO:5, SEQ ID SEQ ID NO: 8. In another specific embodiment, the invention encompasses engineering an anti-FcYRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO: 13 and the light chain variable domain having the amino acid sequence of SEQ ID NO: 14. In another specific embodiment, the invention encompasses engineering a humanized anti-FcyRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:3 and the light chain variable domain having the amino acid sequence of SEQ ID NO:8. In another specific embodiment, the invention encompasses engineering a humanized anti¬FcyRIIB antibody comprising the heavy chain variable domain having the amino acid sequence of SEQ ID NO:9 and the light chain variable domain having the amino acid sequence of SEQ ID NO:10. [00219] In another specific embodiment, the invention encompasses engineering an anti-Fc'yRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/403,266 filed on August 12, 2002, U.S. Application No. 10/643,857 filed on August 14, 2003, U.S. Provisional Application No. 60/562,804 filed on April 16,2004, U.S. Provisional Application No. 60/582,044 filed on June 21, 2004, U.S. Provisional Application No. 60/582,045 filed on June 21,2004, U.S. Provisional Application No. 60/636,663 filed on December 15,2004 and U.S. Application Serial No. 10/524,134 filed February 11,2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc rgion for FcyRflIA and/or FcRIIA. In another specific embo4iment, the invention encompasses engineering a humanized anti-FcyRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/569,882 flIed on May 10, 2004, U.S. Provisional Application No. 60/582, 043 filed on June 21, 2004 and U.S. Application No. 11/126,978, filed on May 10,2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc rgion for FcyRIIIA and/or FcRILA. Each of the above mentioned applications is incorporated herein by reference in its entirety. Examples of anti-FcyRIIB antibodies, which may or may not be humanized, that may be engineered in accordance with the methods of the invention are 2B6 monoclonal antibody having ATCC accession number PTA-4591 and 3H7 having ATOC accession number PTA-4592 ,1D5 monoclonal antibody having ATCC accession number PTA-S 958, 1F2 monoclonal antibody having ATCC accession number PTA-S 959, 2D1 1 monoclonal antibody having ATCC accession number PTA-5960, 2E1 monoclonal antibody having ATCC accession number PTA-5961, 8B5.3.4 having ATOC accession number PTA-76 10, and 21*9 monoclonal antibody having ATCC (all deposited at 10801 University Boul~vicw~ A 02209-20 1 1), which are incorporated herein by reference. In another specific embodiment, modification of the anti-FcRLIB antibody may also further decrease the affinity of the Pc region for FcyRIIB. In yet another specific embodiment, the engineered anti-FcRUB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. [00220] In a specific embgdiment, the invention encompasses engineering an anti¬FcyRIIB antibody according to methods of the present invention that comprises one or more complementarily determining regions (CDRs), preferably all 6 CDRs, of the antibody produced by clone 2B6, 31*7, or 8B5.3.4 with ATCC accession numbers PTA-4591, PTA-4592, and PTA-76 10, respectively (e.g., the heavy chain CDR3). In a specific embodiment, an anti-FoyRJiB antibody engineered according to methods of the invention comprises one or more complementarily determining regions (CDRs), preferably all 6 CDRs, of the antibody produced by clone iDS, 2E1, 2149, 2D11, and 1F2 having ATCC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively (e.g., the heavy chain CDR3). In another embodiment, an anti-FcRIIB antibody engineered according to methods of the invention binds to the same epitope as the mouse monoclonal antibody produced from clone 2B6, 31*7, or 8B5.3.4 with ATCC accession numbers PTA-4591, PTA-4592, and PTA-76 10, respectively and/or competes with the mouse monoclonal antibody produced from clone 2B6, 31*7, or 8B5.3.4 with ATOC accession numbers PTA-4591, PTA-4592, and PTA-76 10, respectively a~ determined, e.g., in an ELISA assay or other appropriate competitive immunoassay, and also binds FcyRIIB with a greater affinity than said antibody or a fragment thereof binds FcyRIIA. In another embodiment, an anti¬FcyRflB antibody engineered according to methods of the invention binds to the same epitope as the mouse monoclonal antibody produced from clone iDS, 2E1, 2149, 2D1 1, and 1F2 having ATCC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, and/or competes with the mouse monoclonal antibody produced from clone iDS, 2E1, 21*9, 2D11, and 1F2 having ATOC Accession numbers, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, as determined, e.g., in an ELISA assay or other appropnate competitive immunoassay, and also binds FcyRflB-, via its variable region, with a greater affinity than said antibody or a fragment thereof binds FcRUA. [00221] The present invention also encompasses engineering an anti-FcyRJIB antibody comprising a heavy chain variable domain and/or light chain variable domain amino acid sequence that is at least 45%, at least 50%, at least 55%, at least 60%, at least 75%, at least 80%, at least 85%, at least at least 99~/o identical to the amino acid sequence of the heavy chain variable domain and/or light chain variable domain of the mouse monoclonal antibody produced by clone 2B6, 31*7, 8B5.3.4, iDS, 2E1, 21*9, 2D1 1, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. The present invention further encompasses the engineering of anti-FcyRIIB antibodies comprising an amino acid sequence of one or more CDRs that is at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the amino acid sequence of one or more QDRs of the mouse monoclonal antibody produced by clone 2B6, 31*7, 8B5.3.4, 1D5, 2E1, 21*9, 2D11, or 1F2 having ATCC accession numbers PTA-4591, PTA¬4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively. The determination of percent identity of two amino acid sequences can be determined by any method known to one skilled in the art, including BLAST protein searches. [002221 The present invention also encompasses the the engineering of one or more anti-Fc'yRIIB antibodies comprising one or more variable domains encoded by a nucleotide sequence that hybridizes to the nucleotide sequence of one or more variable domains of a mouse monoclonal antibody produced by clone 2B6, 31*7, 8B5.3.4, 1D5, 2E1, 21*9, 2D1 I, or 1F2 having ATCC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, under stringent conditions. In a preferred embodiment, the invention encompasses engineering one or more anti¬FcyRIIB antibodies comprising a variable light chain and/or variable heavy chain domain encoded by a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence of the variable light chain and/or variable heavy chain domain of the mouse monoclonal antibody produced by clone 2B6, 31*7, 8B5.3.4, 1D5, 2E1, 21*9, 2D1 1, or 1F2 having ATOC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively, under stringent conditions. In another preferred embodiment, the invention provides engineering anti-FcRIIB antibodies comprising one or more ODRa encoded by a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence of one or more ODRa of the mouse monoclonal antibody produced by clone 2B6, 31*7, 8B5.3.4, lDS, 2E1, 21*9, 2D1 1, or 1F2 having ATOC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA¬5961, PTA-5962, PTA-5960, and PTA-5959, respectively. Stringent hybridization conditions include, but are not limited to, hybridization to filter-bound DNA in 6X sodium (SSC) at about 4500 followed by one or more washes in 0.2X SSC/0.l% SDS at about 50-650C, highly stringent conditions such as hybridization to filter¬boi.ind DNA in 6X SSC at about 450C followed by one or more washes in 0.lX SSC/0.2% SDS at about 600C, or any other stringent hybridization conditions known to those skilled in the art (see, for example, Ausubel, F.M. eta!., eds. 1989 Current Protocols in Molecular Biology, vol. 1, Green Publishing Associates, Inc. and John Wiley and Sons, Inc., NY at pages 6.3.1 to 6.3.6 and 2.10.3, incorporated herein by reference). [00223] In a preferred embodiment, the engineered antibodies of the invention are humanized by any method known in the art or described herein and/or comprise the QDR regions of a humanized FcyRJIB specific antibody or humanized CD2O specific antibody, whrein said CDRs are derived from a murine antibody specific for FcyRflE or CD2O, respectively. In some embodiments, the humanized antibodies described herein comprise alterations, including but not limited to amino acid deletions, insertions, modifications, of the acceptor antibody, i.e., human, heavy and/or light chain variable domain framework regions that are necessary for retaining binding specificity of the donor monoclonal antibody. In some embodiments, the framework regions of the humanized antibodies described herein do not necessarily consist of the precise amino acid sequence of the framework region of a natural occuning human antibody variable region, but contains various alterations, including but not limited to amino acid deletions, insertions, modifications that alter the property of the humanized antibody, for example, improve the binding properties of a humanized antibody variable region specific for the same target as the murine FcyRflB or CD2Q specific antibody. In most preferred embodiments, a minimal number of alterations are made to the framework region in order to avoid large-scale introductions of non-human framework residues and to ensure minimal immunogenicity of the humanized antibody of the invention in humans. The donor monoclonal antibody is preferably a monoclonal antibody produced by clones 2B6, 31*7, 8B5.3.4, 1D5, 2E1, 21*9, 2D1 1, or 1F2 (having ATOC accession numbers PTA-459 1, PTA-4592, PTA-761 0, PTA- 5958, PTA-5961, PTA-5962, PTA-5960, and PTA-5959, respectively) which bind FcyRUB, or the monoclonal antibody is a CD2O antibody, such as rituximab or 21*7. [002241 In a specific embodiment, the invention encompasses engineering a CDR¬grafted antibody that comprises a heavy chain variable region domain comprising framework residues of the recipient antibody and residues from the donor monoclonal antibody, which specifically binds FcyRIIB, e.g., monoclonal antibody produced from ~lones 2B6, 31*7, 8B5.3.4, IDS, 2E1, 21*9, 2D1 1, or 1F2 having ATOC accession numbers PTA-4591, PTA-4592, PTA-7610, PTA-5958, PTA-5961, PTA-5962, PTA-5960, and PTA¬ other specific embodiment, the invention encompasses engineering a CDR-grafted antibody that comprises a light chain variable region domain comprising framework residues of the recipient antibody and residues from the donor monoclonal antibody, which specifically binds FcyRIIB, e.g., monoclonal antibody produced from clones 2B6, 31*7, 8B5.3.4, 1D5, 2E1, 2H9, 2D1 1, or 1F2. [00225] Preferably the FcyRIII3 humanized antibodies bind the extracellular domain of native human Fc'yRIIB. The humanized anti- FcyRI1B antibodies of the combinations can have a heavy chain variable region comprising the amino acid sequence of CDR1 (SEQ ID NO: 15 or SEQ ID NO: 16) and/or CDR2 (SEQ ID NO:17 or SEQ ID NO:18) and/or CDR3 (SEQ ID NO: 19 or SEQ II) NO:20) and/or a light chain variable region comprising the amino acid sequence of CDR1 (SEQ ID NO:21 or SEQ ID NO:22) and/or a CDR2 (SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, or SEQ ID NO:26) and/or CDR3 (SEQ ID NO:27 or SEQ ID NO:28). [00226] In a specific embodiment, the invention encompasses the engineering of a humanized anti-FcyRIIB antibody with the heavy chain variable domain having the amino acid sequence of SEQ ID NQ:l, SEQ ID NO:2, or SEQ ID NO:3 and a light chain variable domain having the amino acid sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6; SEQIDNO:7orSEQIDNO:8. [00227] In one specific embodiment, the invention encompasses engineering a humanized anti-FcyRIIB antibody, wherein the VII region of the FoyRUB antibody consists of the FR segments from the human germline VH segment VH1-18 (Malsuda eta!., 1998, J. Exp. Med. 188:2151062) and 1116 (Ravetch eta!., 1981, Cell 27(3 Pt. 2): 583-91), and one or more CDR regions of a 2B6 VII, having the amino acid sequence of SED ID NO: 1, SEQ ID NO:17, or SEQ ID NO:19. In one embodiment, the 2B6 VII has the amino acid sequence of SEQ IDNO:1, SEQ IDNO:3, or SEQ IDNO:29. In another specific embodiment, the humanized anti-FcyRIIB antibody further comprises a VL region, which consists of the FR segments of the human germline VL segment VK-A26 (Lautner-Rieske et a!., 1992, Eur. J. Immunol. 22:1023-1029) and JK4 (Flieter eta!., 1982, J. Biol. Chem. 257:1516-22), and one or more CDR regions of a 2B6VL, having the amino acid sequence of SEQ ID NO:21, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, and SEQ IDNQ:27. In one embodiment, the 2B6 VL has the amino acid sequence of SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6; SEQ ID NO:7, SEQ ID NO:8, or SEQ ID NO:30, and optionally in combination with one of the above-referenced 2B6 VII. RIIB antibody angineered in accordance with the methods 01 the invention has a VII chain and/or a VII domain comprising the amino acid sequence (1*2B6VH-3): (Sequence Removed)(SEQ II) NO:3). [00229] In some embodiments, the anti-FcyRIIB antibody angineered in accordance with the methods of the invention has a VL chain and/or VL domain comprising the amino acid sequence (1*2B6VL-5): (Sequence Removed) (SEQ ID NO:8). [002301 In some embodiments, the anti-FcRIIB antibody angineered in accordance with the methods of the invention has a VII chain and/or VII domain comprising the amino acid sequence (H2B6VH-3): (Sequence Removed) (SEQ ID NO:3), and a VL chain and/or VL domain comprising the amino acid sequence (H2B6VL-5): EIVIiTQS PDFQSVTPKEKVTFTCRTSQS IGTN II-IWYQQKPDQS PKLLIKEVSESI SGVPSR FSGSGSGTDFTLTINSLEAEDAATYYCQQSNTWPFTFGGGT~IK (SEQ ID NO:8). (Sequence Removed) with the methods of the invention has a VII domain and/or VII chain comprising the amino acid sequence (8B5.3.4 VII, see FIG. 2): (Sequence Removed) (SEQ ID NO:9). [00232] In some embodiments, the anti-FcyRUB antibody angineered in accordance with the methods of the invention has a VL domain and/or VL chain comprising the amino acid sequence (8B5.3.4 VL, see FIG. 1): (Sequence Removed) (SEQ ID NO:lO). [002331 In some embodiments, the anti-FcRUB antibody angineered in accordance with the methods of the invention has a VII domain and/or VII chain comprising the amino acid sequence (8B5.3.4 VII): FSDAWMDWVRQS PEKGLEWVAE I RNKAKNHATY (Sequence Removed)e (8B5.3.4 VL, see FIG 1): (Sequence Removed) (SEQ ID NO:l0). [00234] In another specific embodiment, the anti-FcyRIIB antibody angineered in accordance with the methods of the invention is a humanized 3147 antibody, wherein the FcRIIB Vii region consists of the FR segments from a human germline VII segment and the CDR regions of the 31*7 VII, having the amino acid sequence of SED ID NO: 37. In another specific embodiment, the humanized 31*7 antibody further comprises a VL region, which consists of the FR segments of a human gerinline VL segment and the CDR regions of 3H7VL, having the amino acid sequence of SEQ ID NO:7. [002351 In particular; the invention encompasses the engineering of an anti-FcyRIIB antibody wherein the antibody immunospecifically binds to an extracellular domain of native human FcRHIB, said FcRIIB antibody comprising (or alternatively, consisting of) CDR sequences of 2B6, 3147, or 8B5.3.4 in any of the following combinations: a (Sequence Removed) (~DR3; aVil CDR2, aVII CDR3, aVL CDR1, aVL CDR2, and a VL CDR3; or any combination thereof of the VII CDRs and VL ODRa disclosed herein. [00236] In a specific embodiment, the anti-FcRLIB monoclonal antibody comprises a modification at position 334 with giutamic acid, at position 359 with asparagine, and at position 366 with serine (MgFcl 3); or a substitution at position 316 with aspartic acid, at position 378 with valine, and at position 399 with glutamic acid (MgFc27); or a substitution at position 243 'with isoleucine, at position 379 with leucine, and at position 420 with valine (MgFc29); or a substitution at positon 392 with threonine and at position 396 with leucine (MgFc3 8); or a substitution at position 221 with glutamic acid, at positon 270 with glutamic acid, at positon 308 with alanine, at position 311 with histidine, at position 396 with leveine, and at position 402 with aspartic (MgFc42); or a substitution at position 410 with histidine, and at position 396 with leucine (MgFc53); or a substitution at position 243 with leucine, at position 305 with isoleucine, at position 378 with aspartic acid, at position 404 with serine, and at position 396 with leucine (MgFc54); or a substitution at position 255 with isoleucine, and at position 396 with leucine (MgFc5S); or a substitution at position 370 with glutamic acid3 and at position 396 with leucine (MgFc59); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine (MgFc88); or a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine (MgFc88A); or a substitution at position 234 with leucine, at position 292 with proline, and at position 300 with leucine (MgFcl5S); or a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; or a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; or a substitution at position 243 with leucine, and at position 292 with proline; or a substitution at position 243 with leucine; or a substitution at position 273 with phenylalanine (See Tables 5 & 6). 5.1.1 POLYPEPTID~ AND ANTIBODY CONJUGATES [00231 Molecules of the invention (i.e., polypeptides, antibodies) comprising variant Fe regions may be recombinantly fused or chemically conjugated (including both covalently and non-covalently conjugations) to heterologous polypeptides (i.e., an unrelated polypeptide; or portion thereof, preferably at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90 or at least 100 amino acids of the polypeptide) to generate fusion proteins. The fusion does not necessarily need to be direct, but may occur through linker sequences. upolecules of the invention (i.e., polypeptides, bnuouw~j comprising variant Fc regions may be conjugated to a therapeutic agent or a drug moiety that modifies a given biological response. Therapeutic agents or drug moieties are not to be construed as limited to classical chemical therapeutic agents. For example, the drug moiety may be a protein or polypeptide possessing a desired biological activity. Such proteins may include, for example, a toxin such as abrin, ricin A, pseudomonas exotoxin (i.e., PE-40), or diphtheria toxin, ricin, gelonin, and pokeweed antiviral protein, a protein such as tumor necrosis factor, interferons including, but not limited to, a-interferon (IFN-a), f3-interferon (IFN-~), nerve growth factor (NGF), platelet derived growth factor (PDGF), tissue plasminogen activator (TPA), an apoptotic agent (e.g., TNF-a, TNF-~, AIM I as disclosed in PCT Publication No. WO 97/33 899), AIM II (see, PCT Publication No. WO 97/34911), Fas Ligand (Takahashi eta!., J. Immz*no!., 6:1567-1574, 1994), and VEGI (PCT Publication No. WO 99/23105), a thrombotic agent or an anti-angiogenic agent (e.g., angiostatin or endostatin), or a biological response modifier such as, for example, a lymphokine (e.g., interleukin- 1 ("IL- 1"), interleuldn-2 ("liL-2"), interleukin-6 ("IL-6"), granulocyte macrophage colony stimulating factor ("GM-CSF"), and granulocyte colony stimulating factor ("G-CSF"), macrophage colony stimulating factor, ("M-CSF"), or a growth factor (e.g., growth hormone ("GII"); proteases, or ribonucleases. [00239] Molecules of the invention (i.e., polypeptides, antibodies) can be fused to marker sequences, such as a peptide to facilitate purification. In preferred embodiments, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, CA, 91311), among others, many of which are commercially available. As described in Gentz et a!., 1989, Proc. Nat!. Acad. Sci. USA, 86:821-824, for instance, hexa-histidine provides for convenient purification of the fusion protein. Other peptide tags useful for purification include, but are not limited to, the hemagglutinin "HA" tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., Cell, 37:767 1984) and the "flag" tag (Knappik et a!., Biotechniques, 1 7(4):754-761, 1994). [00240] Additional fusion proteins may be generated through the techniques of gene-shuffling, motif-shuffling, exon-shuffhing, and/or codon-shufiling (collectively referred to as "DNA shuffling"). DNA shuffling may be employed to alter the activities of molecules of the invention (e.g., antibodies with higher affinities and lower dissociation rates). See, generally, U.S. PatentNos. 5,605,793; 5,811,238; 5,830,721; 5,834,252; and 5,837,458, and Patten eta!., 1997, Curr. Opinion Biotechnol. 8:724-33; Harayama, 1998, Trends Blotechno!. 16:76; 1*ansson, etal., 1999, J. Mo!. Biol. 2 87:265; and Lorenzo and Blasco, (each of these patents and publications alv n~ieuy multipuly ateci by reference in its entirety). Molecules of the invention comprising variant Fe regions, or the nucleic acids encoding the molecules of the invention, may be further altered by being subjected to random mutagenesis by error-prone PCR, random nucleotide insertion or other methods prior to recombination. One or more portions of a polynucleotide encoding a molecule of the invention, may be recombined with one or more components, motifs, sections, parts, domains, fragments, etc. of one or more heterologous molecules. [002411 The present invention also encompasses molecules of the invention comprising variant Pc regions (i.e., antibodies, polypeptides) conjugated to a diagnostic or therapeutic agent or any other molecule for which serum half-life is desired to be increased and/or targeted to a particular subset of cells. The molecules of the invention can be used diagnostically to, for example, monitor the development or progression of a disease, disorder or infection as part of a clinical testing procedure to, e.g., determine the efficacy of a given treatment regimen. Detection can be facilitated by coupling the molecules of the invention to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, radioactive materials, positron emitting metals, and nonradioactive paramagnetic metal ions. The detectable substance may be coupled or conjugated either directly to the molecules of the invention or indirectly, through an intermediate (such as, for example, a linker known in the art) using techniques known in the art. See, for example, U.S. Patent No. 4,741,900 for metal ions which can be conjugated to antibodies for use as diagnostics according to the present invention. Such diagnosis and detection can be accomplished by coupling the molecules of the invention to detectable substances including, but not limited to, various enzymes, enzymes including, but not limited to, horseradish peroxidase, alkaline phosphatase, beta-galactosidase, or acetylcholinesterase; prosthetic group complexes such as, but not limited to, streptavidin/biotin and avidin/biotin; fluorescent materials such as, but not limited to, umbelliferone, fluorescein, fluorescein isothiocyanate, rhodaniine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerytbrin; luminescent material such as, but not limited to, luminol; bioluminescent materials such as, but not limited to, luciferase, luciferin, and aequorin; radioactive material such as, but not limited to, bismuth (213Bi), carbon ('4C), chromium (51Cr), cobalt (57Co), fluorine ('3F), gadolinium ('53Gd, 159Gd), gallium (ka, 67~) germanium (Ge), holmium (1~Ho), indium ('151n, luIn, ll2fr,, 1111n), iodine (1311, '~I, 1~I, WI), lanthanium ('~"'La), lutetium (177Lu), manganese ('Mn), molybdenum (~Mo), palladium (1~Pd), phosphorous (32P), praseodymium (142Pr), promethium (149Pm), rhenium (iS6Re, lURe), rhodium ('05Rh), ruthemium (9~Ru), samarium (r'&~cane&un4~S~e), selenium (155e), strontium (855r), sulfur (35S), technetium ("'Tc), thallium (2UITi), tin (I '3Sn, 1175n), tritium (3II), xenon (133Xe), ytterbium ('69Yb, '"Yb) yttrium (90Y), zinc (5Zn); positron emitting metals using various positron emission tomographies, and nonradioactive paramagnetic metal ions. [002421 Molecules of the invention (i.e., antibodies, polypeptides) comprising a variant Fe region may be conjugated to a therapeutic moiety such as a cytotoxin (e.g., a cytostatic or cytocidal agent), a therapeutic agent or a radioactive element (e.g., alpha-emitters, gamma-emitters, etc.). Cytotoxins or cytotoxic agents include any agent that is detrimental to cells. Examples include paclitaxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. Therapeutic agents include, but are not limited to, antimetabolites (e.g., methotrexate, 6-mercaptopurine, 6-thioguanine, cytarabine, 5-fluorouracil decarbazine), alkylating agents (e.g., mechlorethamine, thioepa chiorambucil, melpbalan, cannustine (BSNU) and lomustine (CCNU), cyclothosphamide, busulfan, dibromomannitol, streptozotocin, mitomycin C, and cisdichiorodiarnine platinum (II) (DDP) cisplatin), anthracydlines (e.g., daunorubicin (formerly daunomycin) and doxorubicin), antibiotics (e.g., dactinomycin (formerly actinomycin), bleomycin, mithramycin, and anthramycin (AMC), and anti-mitotic agents (e.g., vincristine and vinblastine). [00243] Moreover, a molecule of the invention can be conjugated to therapeutic moieties such as a radioactive materials or macrocycic chelators useful for conjugating radiometal ions (see above for examples of radioactive materials). In certain embodiments, the macrocycic chelator is 1,4,7, l0-tetraazacyclododecane-N,N',N' ' ,N" '-tetraacetic acid (DOTA) which can be attached to the antibody via a linker molecule. Such linker molecules are commonly known in the art and described in Denardo eta!., 1998, Clin Cancer Res. 4:2483-90; Peterson eta!., 1999, Bioconjug. Chem. 10:553; and Zimmerman et a!., 1999, Nuc!. Med Biol. 26:943-50 each of which is incorporated herein by reference in their entireties. [00244] Techniques for conjugating such therapeutic moieties to antibodies are well known; see, e.g., Anion eta!., "Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy", in Monoclonal Antibodies And Cancer Therapy, Reisfeld et aL (eds.), 1985, pp. 243-56, Alan R. Liss, Inc.); Hellstrom etal., "Antibodies For Drug Delivery", in Contro!led Drug DelIvery (2nd Ed.), Robinson et al. (eds.), 1987, pp. 623-53, Marcel hoxppa Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review", in Monoclonal Antibodies '84: Biological And Clinical Applications, Pinchera et al. (eds.), 1985, pp. 475-506); "Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy", in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et a!. (eds.), 1985, pp. 303-16, Academic Press; and Thorpe eta!., Immunol. Rev., 62:119-58, 1982. [002451 In one embodiment, where the molecule of the invention is an antibody comprising a variant Fc region, it can be administered with or without a therapeutic moiety conjugated to it, administered alone, or in combination with cytotoxic factor(s) and/or cytokine(s) for use as a therapeutic treatment. Alternatively, an antibody of the invention can be conjugated to a second antibody to form an antibody heterooonjugate as described by Segal in U.S. Patent No. 4,676,980, which is incorporated herein by reference in its entirety. Antibodies of the invention may also be attached to solid supports, which are particularly useful for immunoassays or purification of the target antigen. Such solid supports include, but are not limited to, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride or polypropylene. 5.2 SCREENING OF MOLECUI2~ES WITH VARIANT Fc REGIONS FOR ENHANCEI) Fc'tRLLT BINDING AND CHARACTERIZATION OF SAME [00246] In preferred embodiments, screening and identifying molecules comprising variant Fc regions with altered FcR affinities (e.g., enhanced FcRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Fc-FcR interaction, i.e., specific binding of an Fc region to an FcR, including; but not limited to, an ELISA assay, surface plasmon resonance assays, immunoprecipitation assay, affinity chromatography, and equilibrium dialysis. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcyR affinities (e.g., enhanced FcRflIA affinity) are done using the yeast display technology as described herein in combination with one or more functional based assays, preferably in a high throughput manner. The functional based assays can be any assay known in the art for characterizing one or more FcyR mediated efl'ector ccli functions such as those described herein in Section 5.2.7. Non-limiting examples of effector cell functions that can be used in accordance with the methods of the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity (ADCC), antibody-dependent phagocytosis, phagocytosis, cell binding, rosetting, Clq binding, and complement dependent cell mediated cytotoxicity. In some embodiments, screening and identifying molecules comprising variant Fc regions with altered FcyR affinities (e.g., enhanced FcyRIIIA affinity) are done using the yeast display technology as described herein in combination with one or more biochemical based assays in combination or in parallel with one or more functional based assays, preferably in a high throughput manner. [00247] The term "specific binding" of an Fe region to an FcR refers to an interaction of the Fe region and a particular FcR which has an affinity constant of at least about 150 nivI, in the case of monomeric FcyRflIA and at least about 60 nM in the case of dimeric FcRflB as determined using, for example, an ELISA or surface plasmon resonance assay (e.g., a BIAcore"~9. The affinity constant of an Fc region for monomeric FcyRIIIA may be 150 nM, 200 nM or 300nM. The affinity constant of an Fe region for dimeric Fc'yRIIB may be 60 nM, 80 nM, 90 nM, or 100 nM. Dimeric FcyRIIB for use in the methods of the invention may be generated using methods known to one skilled in the art. Typically, the extracellular region of FcRTIB is covalently linked to a heterologous polypeptide which is capable of dimerization, so that the resulting fusion protein is a dimer, e.g, see, U.S. Application No. 60/439,709 filed on January 13, 2003 (Attorney Docket No. 11183-005-888), which is incorporated herein by reference in its entirety. A specific interaction generally is stable under physiological conditions, including, for example, conditions that occur in a living individual such as a human or other vertebrate or invertebrate, as well as conditions that occur in a cell culture such conditions as used for maintaining and culturing mammalian cells or cells from another vertebrate organism or an invertebrate organism. [002481 In a specific embodiment, screening for and identifying molecules comprising variant Fe regions and altered FcR affinities comprise: displaying the molecule comprising a variant Fe region on the yeast stirface; and characterizing the binding of the molecule comprising the variant Fe region to a FcR (one or more), using a biochemical assay for determining Fe-FcR interaction, preferably, an ELISA based assay. Once the molecule comprising a variant Fe region has been characterized for its interaction with one or more FcRs and determined to have an altered affinity for one or more FcRs, by at least one biochemical based assay, e.g., an ELISA assay, the molecule maybe engineered into a complete immunoglobulin, using standard recombinant DNA technology methods known in the art, and the immunoglobulin comprising the variant Fe region expressed in mammalian cells for further biochemical characterization. The immunoglobulin into which a variant Fe introduced (e.g., replacing the Fc region of me lnlmunoglobuun) can be any immunoglobulin including, but not limited to, polyclonal antibodies, monoclonal antibodies, bispecific antibodies, multi-specific antibodies, humanized antibodies, and chimeric antibodies. In preferred embodiments, a variant Fc region is introduced into an immunoglobulin specific for a cell surface receptor, a tumor antigen, or a cancer antigen. The immunoglobulin into which a variant Fc region of the invention is introduced may specifically bind a cancer or tumor antigen for example, including, but not limited to, KS 1/4 pan-carcinoma antigen (Perez and Walker, 1990, J. ImmunoL 142:3662-3667; Bumal, 1988, Hybridoma7(4): 407-415), ovarian carcinoma antigen (CA12S) (Yu eta!., 1991, Cancer Res. 51(2): 468-475), prostatic acid phosphate (Tailor et a!., 1990, Nuc!. Acids Res. 18(16): 4928), prostate specific antigen (Henttu and Vibko, 1989, Biochem. Biophys. Res. Comm. 160(2): 903-910; Israeli etal., 1993, Cancer Res. 53: 227-230), melanoma-associated antigen p97 (Estin et al., 1989,.! Natl. Cancer Instit. 81(6): 445-446), melanoma antigen gp75 (Vijayasardahl etal, 1990,. Exp. Med 171(4): 1375-1380), high molecular weight melanoma antigen (HMW-MAA) (Natali et al., 1987, Cancer 59: 55-63; Mittelman et a!., 1990,.! Clin. Invest. 86: 2 136-2144), prostate specific membrane antigen, carcinoembryonic antigen (CEA) (Foon et a!., 1994, Proc. Am. Soc. Clin. Oncol. 13: 294), polymorphic epithelial mucin antigen, human milk fat globule antigen, colorectal tumor-associated antigens such as: CEA, TAG-72 (Yokata eta!., 1992, Cancer Res. 52: 3402-3408), C017-lA (Ragnhammar eta!., 1993,Int. J. Cancer 53: 751-758); GICA 19-9 (Herlyn et a), 1982, .1 Clin. Immunol. 2:135), CTA-1 and LEA, Burkitt's lymphoma antigen-38.13, CD19 (Ghetie etal, 1994, Blood 83: 1329-1336), human B-lymphoma antigen-CD2O (Reff et a!., 1994, Blood 83:435-445), CD33 (Sgouros eta!., 1993,.! Nuci. Med. 34:422-430), melanoma specific antigens such as ganglioside GD2 (Saleli et a!., 1993, J. Immunol., 151, 3390-3398), ganglioside GD3 (Shitara etal., 1993, Cancer Immuno!. Immunother. 36:373-380), ganglioside GM2 (Livingston eta!., 1994, JJ Clin. Oncol. 12: 1036-1044), ganglioside (3M3 (Hoon et al., 1993, Cancer Res. 53: 5244-5250), tumor-specific transplantation type of cell-surface antigen (TSTA) such as virally-induced tumor antigens including T-antigen DNA tumor viruses and Envelope antigens of RNA tumor viruses, oncofetal antigen-alpha-fetoprotein such as CEA of colon, bladder tumor oncofetal antigen (Hellstrom etal., 1985, Cancer. Res. 45:2210-2188), differentiation antigen such as human lung carcinoma antigen L6, L20 (Helistrom eta!., 1986, Cancer Re:. 46: 3917-3923), antigens of fibrosarcoma, human leukemia T cell antigen-0p37 (Bhattacharya¬Chatterjee eta!., 1988,.! oflmmun. 141:1398-1403), neoglycoprotein, sphingolipids, breast cancer antigen such as EGFR (Epidermal growth factor receptor), HER2 antigen mucin (PEM) (Hilkens eta!., 1992, zrenas mo. Chem. Sd. 17:359), malignant human lymphocyte antigen-APO-l (Bernhard et a!., 1989, Science 245: 301-304), differentiation antigen (Feizi, 1985, Nature 314: 53-57) such as I antigen found in fetal erythrocytes, primary endoderm I antigen found in adult erythrocytes, preimplantation embryos, I(Ma) found in gastric adenocarcinomas, Ml 8, M39 found in breast epithelium, SSEA-1 found in myeloid cells, VEP8, VEP9, Myl, VIM-D5, D156-22 found in colorectal cancer, TRA-l-85 (blood group H), C14 found in colonic adenocarcinoma, F3 found in lung adenocarcinoma, AH6 found in gastric cancer, Y hapten, Le~ found in embryonal carcinoma cells, TL5 (blood group A), EGF receptor found in A43 1 cells , E1 series (blood group B) found in pancreatic cancer, FC1O.2 found in embryonal carcinoma cells, gastric adenocarcinoma antigen, CO-S 14 (blood group J~~) found in Adenocarcinoma, NS-10 found in adenocarcinomas, CO-43 (blood group Leb), G49 found in EGF receptor ofA43l cells, MH2 (blood group ALeb/LeY) found in colonic adenocarcinoma, 19.9 found in colon cancer, gastric cancer mucins, T5A7 found in mycloid cells, R24 found in melanoma, 4.2, GD3, Dl. 1, OFA- 1, G~, OFA-2, GD2, and Ml :22:25:8 found in embryonal carcinoma cells, and SSEA-3 and SSEA-4 found in 4 to 8-cell stage embryos. In one embodiment, the antigen is a T cell receptor derived peptide from a Cutaneous Tcell Lymphoma (see, Edelson, 1998, The Cancer Journa! 4:62). [00249] In some embodiments, a variant Fc region of the invention is introduced into an anti-fluoresceine monoclonal antibody, 4-4-20 (Kranz et a!., 1982 J. Bio!. Chem. 257(12): 6987-6995; which is incorporated herein by reference in its entirety). In other embodiments, a variant Fc region of the invention is introduced into a mouse-human chimeric anti-CD2O monoclonal antibody 2H7, which recognizes the CD2O cell surface phosphoprotein on B cells (Liu eta!., 1987, Journal oflmmuno!ogy, 139: 3521-6; which is incorporated herein by reference in its entirety). In yet other embodiments, a variant Fc region of the invention is introduced into a humanized antibody (Ab4DS) against the human epidermal growth factor receptor 2 (p185 HER2) as described by Carter et at (1992, Proc. Nail. Acad. Sci. USA 89: 4285-9; which is incorporated herein by reference in its entirety). In yet other embodiments, a variant Fe region of the invention is introduced into a humanized anti-TAG72 antibody (CC49) (Sha eta!., 1994 Cancer Blather. 9(4): 341-9). In other embodiments, a variant Fe region of the invention is introduced into Rituxan which is used for treating lymphomas. [00250] In another specific embodiment, the invention encompasses engineering an anti-FcRIiB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/403,266 filed on August 12,2002, U.S. Application No. ~7-fll~4 ~~ugust 14,2003, U.S. Provisional Application Wo U/Z~2,lStJ4 iifed on April 16,2004, U.S. Provisional Application No. 60/582,044 filed on June 21,2004, U.S. Provisional Application No. 60/582,045 filed on June 21,2004, U.S. Provisional Application No. 60/636,663 filed on December 15, 2004 and U.S. Application Serial No. 10/524,134 filed February 11, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc rgion for FcRIIIA and/or FcRilA. In another specific embodiment, the invention encompasses engineering a humanized anti-FcRIIB antibody including but not limited to any of the antibodies disclosed in U.S. Provisional Application No. 60/569,882 filed on May 10,2004, U.S. Provisional Application No. 60/582, 043 filed on June 21,2004 and U.S. Application N~. 11/126,978, filed on May 10, 2005 by modification (e.g., substitution, insertion, deletion) of at least one amino acid residue which modification increases the affinity of the Fc rglon for FcRHIA and/or FcyRJIA. Each of the above mentioned applications is incorporated herein by reference in its entircty. Examples of anti-FcRIIB antibodies, which may or may not be humanized, that may be engineered in accordance with the methods of the invention are 2B6 m~noclonal antibody having ATCC accession number PTA-4591 and 3H7 having ATCC accession number PTA-4592, lDS monoclonal antibody having ATCC accession number PTA-5958, 1F2 monoclonal antibody having ATCC accession number PTA-S 959, 2D1 1 monoclonal antibody having ATCC accession number PTA-5960, 2E1 monoclonal antibody having ATOC accession number PTA-5961 and 2H9 monoclonal antibody having ATOC accession number PTA-5962 (all deposited at 10801 University Boulevard, Manassas, VA 02209-201 1), which are incorporated herein by reference. In another specific embodiment, modification of the anti-FcRIIB antibody may also further decrease the affinity of the Fc region for FcRIIB. In yet another specific embodiment, the engineered anti-FcyRIIB antibody may further have an enhanced effector function as determined by standard assays known in the art and disclosed and exemplified herein. In some embodiments, a variant Fc region of the invention is introduced into a therapeutic monoclonal antibody specific for a cancer antigen or cell surface receptor including but not limited to, Erbituxml (also known as lMC-C225) (ImClone Systems Inc.), a chimerized monoclonal antibody against EOFR HERCEPTIN(~) (Trastuzumab) (Genentech,, CA) which is a humanized anti-HER2 monoclonal antibody for the treatment of patients with metastatic breast cancer; REOPRO® (abciximab) (Centocor) which is an anti-glycoprotein Ub/ifia receptor on the platelets for the prevention of clot formation; ZENAPAX@ (daclizumab) (Roche Pharmaceuticals, Switzerland) which is an immunosuppressive, humanized anti-0D25 monoclonal antibody for the prevention of acute Other examples are a humanized anti-CD 18 V(ab')2 (Genentech); CDP86O which is a humanized anti-CD 18 F(ab~ (Celitech, UK); PR0542 which is an anti¬HIV gpl2O antibody fused with CD4 (Progenics/Genzyme Transgenics); C14 which is an anti-CD 14 antibody (ICOS Pharm); a humanized anti-VEOF IgOl antibody (Genentech); OVAREX~ which is amurine anti-CA 125 antibody (Altarex); PANOREX~ which is a murine anti-17-IA cell surface antigen IgG2a antibody (Glaxo Welicome/Centocor); IMC¬C225 which is a chimeric anti-EGFR IgO antibody (ImClone System); VITAXIN~ which is a humanized anti-aV~3 integrmn antibody (Applied Molecular Evolution/Medlmmune); Campath 1H/LDP-03 which is a humanized anti CDS2 IgGi antibody (Leukosite); Smart M195 which is a humanized anti-CD33 IgO antibody (Protein Design Lab/Kanebo); RJTIJXA1'P~ which is a chimeric anti-CD2O IgGi antibody (IDEC Pharm/Genentech, Roche/Zettyalcu); LYMPH0CIDE~ which is a humanized anti-CD22 IgO antibody (Immunomedics); Smart ID 10 which is a humanized anti-HLA antibody (Protein Design Lab); ONCOLYMTTM (Lym-l) is a radiolabelled murine anti-HLA DR antibody (Techniclone); anti-CD 1 Ia is a humanized IgGI antibody (Genetech/Xoma); ICM3 is a humanized anti-ICAM3 antibody (ICOS Pharm); IDEC-l 14 is a primatized anti-CD8O antibody (IDEC Pharm/Mitsubishi); ZEVALIN~ is a radiolabelled murmne anti-CD2O antibody (IDEC/Schering AG); IDEC-1 31 is a humanized anti-CD4OL antibody (IDECfEisai); TDEC-l5l is a primatized anti-CD4 antibody (IDEC); IDEC-152 is a primatized anti-CD23 antibody (IDEC/Seikagaku); SMART anti-CD3 is a humanized anti¬CD3 IgG (Protein Design Lab); 5G1.l is a humanized anti-complement factor 5 (CS) antibody (Alexion Pharm); IDEC-151 is a primatized anti-CD4 IgGI antibody (IDEC Pharm/SmithKline ~eecham); MDX-CD4 is a human anti-CD4 IgO antibody (Medarex/Eisai/Genmab); CDP57I is a humanized anti-TNF-a IgG4 antibody (Celltech); LDP-02 is a humanized anti-a4f37 antibody (LeukoSite/Genentech); OrthoClone OKT4A is a humanized anti-CD4 IgG antibody (Ortho Biotech); ANTQVATh is a humanized anti¬CD4OL IgG antibody (Biogen); ANThGR.ENTh is a humanized anti-VLA-4 IgG antibody (Elan); MDX-33 is a human anti-CD64 (FcR) antibody (Medarex/Centeon);; rhuMab-E25 is a humanized anti-IgE IgGi antibody (Genentech/Norvartis/Tanox Biosystems); IDEC¬152 is a primatized anti-CD23 antibody (IDEC Pharm); ABX-CBL is a murine anti CD-147 1gM antibody (Abgenix); BTI-322 is a rat anti-CD2 lgG antibody (Medimmune/Bio Transplant); Orthoclone/OKT3 is a murine anti-CD3 IgG2a antibody (ortho Biotech); SIMULECT~ is a chimeric anti-CD25 IgGi antibody (Novartis Pharm); LDP-O1 is a humanized anti-f3rintegrin IgG antibody (LeukoSite); Anti-LFA-1 is a murine anti CD18 i~Ia~)z ~a3teiIril~4,~i~ic/Immunotech); CAT-l 52 is a human anti (Cambridge Ab Tech); and Corsevin M is a chirneric anti-Factor VII antibody (Centocor). [00251] The variant Fe regions of the invention, preferably in the context of an immunoglobulin, can be further characterized using one or more biochemical assays and/or one or more functional assays, preferably in a high throughput manner. In some alternate embodiments, the variant Fc regions of the inventions are not introduced into an immunoglobulin and are further characterized using one or more biochemical based assays and/or one or more functional assays, preferably in a high throughput manner. The one or more biochemical assays can be any assay known in the art for identifying Fc-FcyR interactions, including, but not limited to, an ELISA assay, and surface plasmon resonance-based assay for determining the kinetic parameters of Fc-FcyR interaction, e.g., BlAcore assay. The one or more functional assays can be any assay known in the art for characterizing one or more FcR mediated effector cell function as known to one skilled in the art or described herein. In specific embodiments, the immunoglobulins comprising the variant Fc regions are assayed in an ELISA assay for binding to one or more FcyRs, e.g., FcRilIA, Fc~yRIIA, Fc'yRIIA; followed by one or more ADCC assays. In some embodiments, the immunoglobulins comprising the variant Fc regions are assayed further using a surface plasmon resonance-based assay, e.g., BlAcore. Surface plasmon resonance-based assays are well known in the art, and are further discussed in Section 5.2.7, and exemplified herein in Example 6.8. [002521 An exemplary high throughput assay for characterizing immunoglobulins comprising variant Fc regions may comprise: introducing a variant Fe region of the invention, e.g., by standard recombinant DNA technology methods, in a 4-4-20 antibody; characterizing the specific binding of the 4-4-20 antibody comprising the variant Fe region to an FcR (e.g., FcRIHA, FcRTIB) in an ELISA assay; characterizing the 4-4-20 antibody comprising the variant Fe region in an ADCC assay (using methods disclosed herein) wherein the target cells are opsonized with the 44-20 antibody comprising the variant Fe region; the variant Fe region may then be cloned into a second imniunoglobulin, e.g., 4D5, 2H7, and that second immunoglobulin characterized in an ADCC assay, wherein the target cells are opsonized with the second antibody comprising the variant Fe region. The second antibody comprising the variant Fe region is then further analyzed using an ELISA-based assay to confirm the specific binding to an FcR. [002531 Preferably, a variant Fe region of the invention binds FcRYIIA and/or FcRITA with a higher affinity than a wild type Fe region as determined in an ELISA assay. Fe region of the invention binds FcyRJIIA ana,or reyzuw~ wim a higher affinity and binds FcRIIB with a lower affinity than a wild type Fe region as determined in an ELISA assay. In some embodiments, the variant Fe region binds FcRiIIA and/or FcRIIA with at least 2-fold higher, at least 4-fold higher, more preferably at least 6-fold higher, most preferably at least 8 to 10-fold higher affinity than a wild type Fe region binds FcRJIIA and/or FcRIIA and binds FcyRJIB with at least 2-fold lower, at least 4-fold lower, more preferably at least 6-fold lower, most preferably at least 8 to 10-fold lower affinity than a wild type Fe region binds FcyRIIB as determined in an ELISA assay. [00254] The immunoglobulin comprising the variant Fe regions may be analyzed at any point using a surface plasmon based resonance based assay, e.g., BlAcore, for defining the kinetic parameters of the Fe-FcR interaction, using methods disclosed herein and known to those of skill in the art. Preferably, the Kd of a variant Fe region of the invention for binding to a monomeric FcRIIIA and/or FcRIJA as determined by BIAcore analysis is about 100 nM, preferably about 70 nM, most preferably about 40 nM.; and the Kd of the variant Fc region of the invention for binding a dimeric FcRIiB is about 80 nM, about 100 nM, more preferably about 200 nM. [00255] In most preferred embodiments, the immunoglobulin comprising the variant Fc regions is further characterized in an animal model for interaction with an FcR. Preferred animal models for use in the methods of the invention are, for example, transgenic mice expressing human FcRs, e.g., any mouse model described in U.S. Patent No. 5,877,397, and 6,676,927 which are incorporated herein by reference in their entirety. Transgenic mice for use in the methods of the invention include, but are not limited to, nude knockout FcRJIIA mice carrying human FcRIIIA; nude knockout FcRflIA mice carrying human FcRIlA; nude knockout FcR.UlAmice carrying human FCRlIB and human FcRIIIA; nude knockout FcRIIIA mice carrying human FcRIiB and human FcRILA; nude knockout FcRIIIA and FcRJiA mice carrying human FcRIUA and FcRIIA and nude knockout FcRflIA, FcRIIA and FcRUB mice carrying human FcRIIIA, FcRilA and FcRIIB. 5.2.1 DESIGN STRATEGiES [00256] The present invention encompasses engineering methods to generate Fe variants including but not limited to computational design strategies, library generation methods, and experimental production and screening methods. These strategies may be various combinations to engineer the Fc vatiints oi me invention. [00257] In most preferred embodiments, the engineering methods of the invention comprise methods in which amino acids at the interface between an Fc region and the Fc ligand are not modified. Fc ligands include but are not limited to FcRs, Clq, FeRn, C3, mannose receptor, protein A, protein 0, mannose receptor, and undiscovered molecules that bind Fe. Amino acids at the interface between an Fe region and an Fe ligand is defined as those amino acids that make a direct and/ or indirect contact between the Fc region and the ligand, play a structural role in determining the conformation of the interface, or are within at least 3 angstroms, preferably at least 2 angstroms of each other as determined by structural analysis, such as x-ray crystallography and molecular modeling The amino acids at the interface between an Fc region and an Fc ligand include those amino acids that make a direct contact with an FcR based on crystallographic and structural analysis of Fc-FcR interactions such as those disclosed by Sondermann et al., (2000, Nature, 406: 267-273; which is incorporated herein by reference in its entirety). Examples of positions within the Fc region that make a direct contact with FcR are amino acids 234-239 (hinge region), amino acids 265-269 (B/C loop), amino acids 297-299 (C'/E loop), and amino acids 327-332 (FIG) loop. In some embodiments, the molecules of the invention comprising variant Fc regions comprise modification of at least one residue that does not make a direct contact with an FcR based on structural and crystallographic analysis, e.g., is not within the Fe¬FcR binding site. [00258] Preferably, the engineering methods of the invention do not modify any of the amino acids as identified by Shields et al,. which are located in the CH2 domain of an Fe region proximal to the hinge region, e.g., Leu234-Pro238; Ala327, Pro329, and affect binding of an Fc region to all human FcRs. [00259] In other embodiments, the invention encompasses Fc variants with altered FcR affinities and/or altered effector functions, such that the Fe variant does not have an amino acid modification at a position at the interface between an Fe region and the Fe ligand. Preferably, such Fe variants in combination with one or more other amino acid modifications which are at the interface between an Fe region and the Fe ligand have a further impact on the particular altered property, e.g. altered FcR affinity. Modifying amino acids at the interface between Fe and an Fc ligand may be done using methods known in the art, for example based on structural analysis of Fe-ligand complexes. For example but not by way of limitation by exploring energetically favorable substitutions at positionsibatmn1 the binding interface, variants can be engineered that sample new interlace conformations, some of which may improve binding to the Fe ligand, some of which may reduce Fe ligand binding, and some of which may have other favorable properties. Such new interface conformations could be the result of, for example, direct interaction with Fc ligand residues that form the interface, or indirect effects caused by the amino acid modifications such as perturbation of side chain or backbone conformations [00260] The invention encompasses engineering Fc variants comprising any of the amino acid modifications disclosed herein in combination with other modifications in which the conformation of the Fc carbohydrate at position 297 is altered. The invention encompasses conformational and compositional changes in the N297 carbohydrate that result in a desired property, for example increased or reduced affinity for an FcR. Such modifications may further enhance the phenotype of the original amino acid modification of the Fe variants of the invention. Although not intending to be bound by a particular mechanism of actions such a strategy is supported by the observation that the carbohydrate structure and conformation dramatically affect Fe-FcR and Fe/Cl q binding (Umaha et aL, 1999, Nat Biotechnol 17:176-180; Davies et aL, 2001, Biotechnol Bioeng 74:288-294; Mimura et aL, 2001, J Biol Chem 276:45539 ; Radaev et aL, 2001, J Biol Chem 276:16478-16483; Shields et aL 2002, J fbI Chem 277:26733-26740; Shinkawa et aL, 2003, J Biol Chem 278:3466-3473). [00261] Another design strategy for generating Fe variants in accordance with the invention is provided in which the Fe region is reengineered to eliminate the structural and functional dependence on glycosylation. This design strategy involves the optimization of Fe structure, stability, solubility, and/or Fc function (for example affinity of Fe for one or more Fe ligands) in the absence of the N297 carbohydrate. In one approach, positions that are exposed to solvent in the absence of glycosylation are engineered such that they are stable, structurally consistent with Fe structure, and have no tendency to aggregate. Approaches for optimizing aglycosylated Fe may involve but are not limited to designing amino acid modifications that enhance aglycoslated Fe stability and/or solubility by incorporating polar and/or charged residues that face inward towards the Cg2-Cg2 dimer axis, and by designing amino acid modifications that directly enhance the aglycosylated Fe¬FcR interface or the interface of aglycosylated Fe with some other Fe ligand. [00262] The Fe variants of the present invention may be combined with other Fe modifications, including but not limited to modifications that alter effector function. The invention encompasses combining an Fe variant of the invention with other Fe modifications to provide additive, synergistic, or novel properties in antibodies or Fe eations may be in the CR1, CR2, or CR3 domains or a combination thereof. Preferably the Fc variants of the invention enhance the property of the modification with which they are combined. For example, if an Fc variant of the invention is combined with a mutant known to bind FcyRIIIA with a higher affinity than a comparable molecule comprising a wild type Fc region; the combination with a mutant of the invention results in a greater fold enhancement in FcRIIIA affinity. [00263] In one embodiment, the Fe variants of the present invention may be combined with other known Fe variants such as those disclosed in Duncan et al, 1988, Nature 332:563-564; Lund et al., 1991, J. Immunol 147:2657-2662; Lund et al, 1992, Mol Immunol 29:53-59; Alegre et al, 1994, Transplantation 57:1537-1543; Hutchins et al., 1995, ProcNail. Acad SciUS A 92:11980-1 1984; Jefferisetal, 1995, Immunol Lett. 44:111-1 17; Lund etal., 1995, FasebJ9:115-l 19; Jefferisetal, 1996, Immunol Lett 54:101-104; Lund et al, 1996, J Immunol 157:49634969; Armour et aL, 1999, Eur J Immunol 29:2613-2624; Idusogie et al, 2000, J Immunol 164:41784184; Reddy et al, 2000, J Immunol 164:1925-1933; Xu et al., 2000, Cell Immunol 200:16-26; Idusogie et al, 2001, J Immunol 166:2571-2575; Shields et al., 2001, J Biol Chem 276:6591-6604; Jefferis et al, 2002, Immunol Lett 82:57-65; Presta et at., 2002, Biochem S~c Trans 30:487490); US 5,624,821; US 5,885,573; US 6,194,551; PCT WO 00/42072; PCT WO 99/58572; each of which is incorporated herein by reference in its entirety. 5.2.2 FcyR-Fc BiTiDING ASSAY [00264] An FcR-Fe binding assay was developed for determining the binding of the molecules of the invention comprising variant Fe regions to FcR, which allowed detection and quantitation of the interaction, despite the inherently weak affinity of the receptor for its ligand, e.g., in the micromolar range for FcRIIB and FcRIHA. The method involves the formation of an FcR complex that has an improved avidity for an Fe region, relative to an uncomplexed FcR According to the invention, the preferred molecular complex is a tetrameric immune complex, comprising: (a) the soluble region of FcR (e.g., the soluble region of FcRIIIA, FcRIIA or FcRIIB); (b) a biotinylated 15 amino acid AViTAG sequence (AVITAG) operably linked to the C-terminus of the soluble region of FcR (e.g., the soluble region of FcRIIIA, FcRIIA or FcRflB); and (c) streptavidin-phycoerythrin (SA-PE); in a molar ratio to form a tetrameric FoyR complex (preferably in a 5:1 molar ratio). According to a preferred embodiment of the invention, the fusion protein is biotinylated enzymatically, using for example, the E.colz Bir A enzyme, a biotin ligase which specifically biotinylates a lysine residue in the 15 amino acid AVITACJ sequence. In of the invention, 85% of the fusion protein is biotinylated, as determined by standard methods known to those skilled in the art, including but not limited to streptavidin shift assay. According to preferred embodiments of the invention, the biotinylated soluble FcR proteins are mixed with SA-PE in a lX SA-PE:5X biotinylated soluble FcR molar ratio to form a tetrameric FcR complex. [00265] In a preferred embodiment of the invention, polypeptides comprising Fc regions bind the tetrameric FcR complexes, formed according to the methods of the invention, with at least an 8-fold higher affinity than the monomeric uncomplexed FcR.. The binding of polypeptides comprising Fc regions to the tetrameric FcR complexes may be determined using standard techniques known to those skilled in the art, such as for example, fluorescence activated cell sorting (FAGS), radioimmunoassays, ELISA assays, etc. [00266] The invention encompasses the use of the immune complexes formed according to the methods described above, for determining the functionality of molecules comprising an Fe region in cell-based or cell-free assays. [00267] As a matter of convenience, the reagents may be provided in an assay kit, i.e., a packaged combination of reagents for assaying the ability of molecules comprising variant Fe regions to bind FcR tetrameric complexes. Other forms of molecular complexes for use in determining Fc-FcyR interactions are also contemplated for use in the methods of the invention, e.g., fusion proteins formed as described in U.S. Provisional Application 60/439,709, filed on January 13, 2003 (Attorney Docket No. 11183-005-888); which is incorporated herein by reference in its entirety. 5.2.3 MUTAGENESIS AND CONSTRUCTION OF YEAST DISPLAY LIBRARIES [00268] Molecular interactions between the IgG Fe and Fe receptors have been previously studied by both structural and genetic techniques. These studies identified amino acid residues that are critical for functional binding of Fe to different FcR. None of these changes have been shown to improve human FcR mediated efficacy of therapeutic antibodies in animal models. A complete analysis of all potential amino acid changes at these residues or other potentially important residues has not been reported. The platform described herein has the ability to both construct mutant libraries with all possible amino acid changes, screen libraries using multiple functional assays, and finally analyze libraries in relevant humanized animal models. [00269] The instant invention encompasses construction of multiple libraries based on both genetic and structural data known in the art or being developed. The method ~nduii~Iifl~d herein incorporates building individual libraries that contata mutants testing all 20 amino acid changes at between 3-6 residues in the Fe region. The complete set of mutations will be assembled in all possible combinations of mutations. The number of independent mutations generated is based on the number of sites being saturated during library assembly (Table 9 below). Library size will determine the choice of primary screen and therefore the choice of vector for initial cloning steps. Table 9: Number of Independent mutants based on number of targeted sites. (Table Removed) [00270] The instant invention encompasses construction of combinatorial libraries, focusing on a limited number of critical residues (e.g., 3-6). Using a library of randomly mutagenized IgGi Fe and the screening assays described and exemplified herein Fc variants will be identified. In the initial rounds, the best S mutations, based on both FcR binding profile and functional activity will be selected. It will take 20~ individual mutants to cover all possible amino acid changes and their combinations at five locations. A library with at least 10-fold coverage for each mutant will be generated. In addition regions will be chosen based on available information, e.g., crystal structure data, Mouse/Human isotype FcR binding differences, genetic data, and additional sites identified by mutagenesis. 100271] The biggest disadvantage of current site directed mutagenic protocols is production of bias populations~ over-representing variations in some regions and under-representing or completely lacking rni~tations in others. The present invention overcomes this problem by generating unbiased arrays of desirable Fc mutants using a well-developed gene building technology to eliminate the bias introduced in library construction by PCR based approaches such as overlapping POR and inverted PCR. The key distinctions of the approach of the present invention are: 1) Employment of equimolar mix of 20 individual oligos for every targeted codon instead of degenerated primers. This way each amino acid is represented by a single, most used codon, whereas degenerated primers over represent those amino acids encoded by more codons over those encoded by fewer codons. 2) Building mutants by a chain replacement approack This insures unbiased introduction of all desirable changes into the final product. [00272] An exemplary protocol comprises of the following steps: 1) phosphorylated oligos, representing desirable changes at one or several locations, all complementary to the same strand, added to the template along with a thermostable, 5'>3' exonuclease deficient, DNA polymerase and ligase (FIG. 27 a). 2) assembled mix undergoes a number of , sufficient to generate desirable amount of product. Use of a 5'3' exonuclease deficient DNA polymerase insures integrity of the primer sequence and its phosphate residue, when a thermostable ligase assembles individual primer-extended fragments into a contiguous single-stranded chaln. Reaction cycles can continue until complete exhaustion of the oligos pool without introducing bias into the final product (FIG. 27 b). 3) generated pool of single-stranded mutants is converted into double-stranded DNA by adding a reverse gene-specific primer to the reaction (FIG. 27 lc). 4) double-stranded product gets digested at the end-designed restriction sites and cloned into an appropriate expression vector (FIG. 27 id) [00273] To insure quality of the library, POR amplified fragments will be analyzed by electrophoresis to determine the length of the final POR products. The reaction will be characterized as successful if >99% of the POR products are of the expected length. The final library will be cloned into an expression vector. A fraction of the mutant library will be sequenced to determine the rate of mutant codon incorporation. The number of fragments sequenced will be based on the number of target sites mutated and library validation will be determined by the observed rate of mutation at targeted sites (Table 10). The rate of vector without inserts should be less than 2 %. The rate of mutation at non-targeted sites should be less than 8%. Libraries containing clones with >90% correct inserts will allow us to maintain screening timelines. TABLE 10 Expected rates of Mutation for Libraries (Table Removed) [00274] In other embodiments, the invention the invention encompasses overlapping or inverted PCR for construction of libraries. In order to remain unbiased, individual primers for each codon will be used rather than degenerative primers. A similar validation scheme as disclosed supra will be employed. [00275] Most preferably automated protocols will be employed for high throughput library production. Automation allows for improved throughput, walk away operation, and cperimental error for tasks requiring tedious repetitive operations. Oligo synthesis capabilities is based on 2 Mermade DNA synthesizers (Bioautomation, Inc.) with a total output capability of 575 60mer Oligos/12 hrs. Proprietary software handies all aspects of design, synthesis, and storage of the final oligonucleotides. Robotic liquid handlers will be employed to set up oligos for synthesis of full length Fc mutants and ligation reactions for incorporating the mutant Fcs into antibody heavy chain expression vectors will be set up. After ligation it is estimated that it would take I ETE —10 days to array the library clones and generate —8O00 minipreps, equivalent to a combinatorial library saturated at 3 sites. Subsequent to bacterial transformation a Qpix-2 clone picker robot will be used for picking colonies into 96 deep well plates. Culture growth will be done using a magnetic levitation stirrer, capable ~f incubating 12 plates and resulting in dense growth in 12-16 hr at 370 C. A Qiagen ruiniprep robot will be used to perform DNA preps at the rate of 496 well plates in 2.5 ins. By overlapping tasks 5 such libraries could be constructed in 9 months with 1 FTE [002 76] Allinity maturation requires the assembly of a new set of combinations of mutations, from a preselected mutant pool or members of a gene family, which can be enriched by a selection protocol. The process is repeated several times until the isolation of a mutant with the desired phenotype is achieved. The disadvantage of the current enzymatic approach, DNA shuffling, to accomplish this process is bias which can be introduced due to specific sites within gene that are hot spots for nucleases, dominance of specific mutants in the final reassembled pool and loss of some of the original mutants in the final pool. In order to overcome this shortcoming a build-a-gene (BAG) technology will be used to generate a highly complex library of Fc mutants containing random amino acid changes at all potential locations that may be important for receptor(s) binding. Sets of degenerated oligos covering specific regions of the IgG Fc will be used (See FIG. 28). [00277] Oligos will be -30 nt and and degenerate oligos synthesized to change one (4 oligos) or two AAs (8 oligos) will be constructed. The oligos are designed to be overlapping with no gaps. It will take —200 oligos to accommodate all single AA changes and -2000 to change two AAs per oligonucleotide. All 2000+ oligos will be used individually and in combinations to generate arrays of Fe mutants using the protocol outlined above (A.20). We will use a home-written randomizer program and a robotic liquid handler for pooling selected combinations of mutant and wild type oligos. Large libraries will be cloned into vectors that will allow for screening using yeast surface display. This approach utilizes a magnetic bead selection followed by flow cytoinetry and has been successfully applied to libraries with a complexity (Feldhaus et al, 2003, Nat which is incorporated herein by reference in its entirety). lbis limits the number of sites to test at any one pool to 7, resulting in —1.3 x 1 ~ possible mutations/pool. [002781 To insure quality of the library PCR amplified fragments will be analyzed by electrophoresis to determine the length of the final PCR products. The reaction will be characterized as successful if >99% of the PCR products are of the expected length. A fraction of the mutant library will be sequenced to determine the rate of mutant codon incorporation. The number of fragments sequenced will be based on the number of target sites mutated and library validation will be determined by the observed rate of mutation at targeted sites (Table 10). The rate of vectors without inserts should be less than 2 %. The rate of mutation at non-targeted sites should be less than 8%. [002791 The ability to generate the desired level of efficiency of mutagenesis by this approach will be determined by sequencing of a subset of clones. The alternative to BAG will be using a "DNA shuffle" protocol. This requires pooling all of the mutants, single, double, triple, etc. Following DNA preparation, Fc regions will be amplified by PCR using flanking primers that selectively amplify the mutated region of the Fc, —700 bp. Novel mutants are constructed by reshuffling of mutations in the Fe via DNAseI treatment of the amplified DNA and isolation of 150-200 bp fragments (see, e.g., Stemmer et al., 1994, Proc. Natl. Acad. Sci. U.S.A. 91:10747-51). Fragments will be religated, PCR amplified with nested primers and cloned into the yeast surface display vector, pYDl. The recombined library will be reselected in the yeast Fc display screen as described and exemplified herein. [002801 BAG libraries will utilize most of the same equipment as the combinatorial library. However cloning will be in a vector suitable for yeast surface display and will not require arraying of individual clones as the yeast surface display will initially be employed for enrichment of large libraries. Subsequent to the appropriate level of enrichment individual clones will be arrayed. [002811 An initial library of molecules comprising variant Fe regions is produced using any random based mutagenesis techniques known in the art. It will be appreciated by one of skill in the art that amino acid sequence variants of Fe regions may be obtained by any mutagenesis technique known to those skilled in the art. Some of these techniques are briefly described herein, however, it will be recognized that alternative procedures may produce an equivalent result In a preferred embodiment molecules of the invention comprising variant Fe regions are prepared by error-prone PCR as exemplified in Example 6, infra (See Leung et al., 1989, Technique, 1:1 1). It is especially preferred to have error in the methods of the invention. In one embodiment, using error prone PCR a mutation frequency of 2-3 mutations/kb is obtained. [00282] Mutagenesis may be performed in accordance with any of the techniques known in the art including, but not limited to, synthesizing an oligonucleotide having one or more modifications within the sequence of the Fc region of an antibody or a polypeptide comprising an Fe region (e.g., the CH2 or CH3 domaln) to be modified. Site-specific mutagenesis allows the production of mutants through the use of specific oligonucleotide sequences which encode the DNA sequence of the desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides of the deletion junction being traversed. Typically, a primer of about 30 t~ about 45 nucleotides or more in length is preferred, with about 10 to about 25 or more residues on both sides of the junction of the sequence being altered. A number of such primers introducing a variety of different mutations at one or more positions may be used to generated a library of mutants. [00283] The technique of site-specific mutagenesis is well known in the art, as exemplified by various publications (see, e.g., Kunkel et al., Methods Enzymol., 154:367-82, 1987, which is hereby incorporated by reference in its entirety). In general, site-directed mutagenesis is performed by first obtaining a single-stranded vector or melting apart of two strands of a double stranded vector which includes within its sequence a DNA sequence which encodes the desired peptide. An oligonucleotide primer bearing the desired mutated sequence is prepared, generally synthetically. This primer is then annealed with the single-stranded vector, and subjected to DNA polymerizing enzymes such as T7 DNA polymerase, in order to complete the synthesis of the mutation-bearing strand. Thus, a heteroduplex is formed wherein one strand encodes the original non-mutated sequence and the second strand bears the desired mutation. This heteroduplex vector is then used to transform or transfect appropriate cells, such as E. coli cells, and clones are selected which include recombinant vectors bearing the mutated sequence arrangement. As will be appreciated, the technique typically employs a phage vector which exists in both a single stranded and double stranded form. Typical vectors useful in site-directed mutagenesis include vectors such as the M13 phage. These phage are readily commercially available and their use is generally well known to those skilled in the art. Double stranded plasmids are also routinely employed in site directed mutagenesis which eliminates the step of transferring the gene of interest from a plasmid to a phage. [002841 Alternatively, the use of PCR~' with commercially available thermostable enzymes such as Taq DNA polymerase may be used to incorporate a mutagenic to an amplified DNA fragment that can then be cloned into an appropriate cloning or expression vector. See, e.g., Tomic etal., Nucleic Acids Res., 18(6):1656, 1987, and Upender eta!., Biotechniques, 18(1):29-30, 32, 1995, for PCRTM -mediated mutagenesis procedures, which are hereby incorporated in their entireties. PCRTh employing a thermostable ligase in addition to a thermostable polymerase may also be used to incorporate a phosphorylated mutagenic oligonucleotide into an amplified DNA fragment that may then be cloned into an appropriate cloning or expression vector (see e.g., Michael, Biotechniques, 16(3):410-2, 1994, which is hereby incorporated by reference in its entirety) [00285] Another method for preparing variants for use in the invention, is cassette mutagenesis based on the technique described by Wells eta!. (1985, Gene, 34: 315). The starting material is the plasmid comprising the desired DNA encoding the protein to be mutated (e.g., the DNA encoding a polypeptide comprising an Fc region). The codon(s) in the DNA sequence to be mutated are identified; there must be a unique restriction endonuclease site on each side of the identified mutations site(s). If no such restriction site exits, it may be generated by oligonucleotide directed mutagenesis. After the restriction sites have been introduced into the plasmid, the plasmid is cut at these sites and linearized. A double-stranded oligonucleotide encoding the sequence of the DNA between the restriction sites but containing the mutation is synthesized using standard procedures known to those skilled in the art. The double stranded oligonucleotide is referred to as the cassette. This cassette is designed to have 3' and 5' ends that are compatible with the ends of the linearized plasmid, such that it can be directly ligated to the plasmid. [00286] Other methods known to those of skill in the art for producing sequence variants of the Fc region of an antibody or polypeptides comprising an Pc region can be used. For example, recombinant vectors encoding the amino acid sequence of the constant domain of an antibody or a fragment thereof may be treated with mutagenic agents, such as hydroxylamine, to obtain sequence variants. [002871 Once a mutant library is produced according to the methods described, the mutagenized library is transformed into a yeast strain, preferably EBY100 (Invitrogen), MATa ura3 -52 Irpi leu2Al his3A200pep4::HIS3prblAl.6R can) GAL::GAL-AGAI using a standard lithium acetate transformation protocol known to those skilled in the art (ref). [002881 It will be appreciated by one of skill in the art, that once molecules of the invention with desired binding properties (e.g., molecules with variant Pc regions with at least one amino acid modification, which modification enhances the affinity of the variant Pc region for FcyRflIA relative to a comparable molecule, comprising a wild-type Fe region) have been identified (See Section 5.1 and Table 2) according to the methods of the (i.e, therapeutic antibodies) may be engineered using standard recombinant DNA techniques and any known mutagenesis techniques, as described in this section to produce engineered molecules carrying the identified mutation sites. 5.2.4 YEAST SURFACE DISPLAY [00289] The preferred method for screening and identifying molecules comprising variant Fc regions with altered FcTR affThities (i.e., enhanced FcyRIIIA affinity and/or FcRIIA) is yeast surface display technology (for review see Boder and Wittrup, 2000, Methods in Enzymo!ogy, 328: 430-444, which is incorporated herein by reference in its entirety) which addresses the deficiency in the prior art for screening binding interactions of extracelli.ilar post-translationally modified proteins. Specifically, the yeast surface display is a genetic method whereby polypeptides comprising Fe mutants are expressed on the yeast cell wall in a form accessible for interacting with FcR. Yeast surface display of the mutant Fc containing polypeptides of the invention may be performed in accordance with any of the techniques known to those skilled in the art. See U.S. Patent No.'s 6,423,538; 6,114,147; and 6,300,065, all of which are incorporated herein by reference in their entirety. See Boder etal., 1997 Nat. Biotechnol., 15:553-7; Boder eta!., 1998 Biotechno!. Pro g., 14:55-62; Boder etal., 2000 Methods Enzymol., 328:430-~; Boder etal., 2000 Proc. Nat!. Acadl Sci. US.A., 2000, 97:10701-5; Shusta etal., 1998 Nat. Biotechnol., 1998, 16:773-7; Shusta eta!., 1999 J. Mo!. Rio!., 292:949-56; Shusta etal., 1999 Curr. Opin. Biotechno!., 10:117-22; Shustaet al., 2000 Nat. Biotechnol., 18:754-9; Wittrup eta!., 1994 Ann. N.Y Acadl Sci., 745:321-30; Wittrup eta!., 1994 Cytometry, 16:206-13; Wittrup, 1995 Curr. Opin. Biotechno!., 6:203-8; Wittrup, 1999 Trends Biotechno!., 17:423-4; Wittrup, 2000 Nat. Biotechnol., 18:1039-40; Wittrup, 2001 Curr. Opin. Biotechnol., 12:395-9. [00290] Yeast Surface Display will be used to enrich libraries containing independent clones. This approach will provide the ability to cigich large libraries >20-fold in single sort. Fe mutant libraries with >10,000 independent mutants (4 or more sites) will be cloned into the appropriate vectors for yeast surface display and enriched by FACS sorting until [00291] The invention provides methods for constructing an Fe mutant library in yeast for displaying molecules comprising Fe regions, which have been mutated as described in Section 5.2.2. Prefereably, the Fe mutant libraries for use in the methods of the invention contain at least ~ cells, up to l0~ cells. One exemplary method for constructing a Fe library for use in the methods of the invention comprises the following: nucleic acids dingnlolo4ates c~iprising Fe regions are cloned into the multiple cloning site of a vector derived from a yeast replicating vector, e.g., pCT3 02; such that the Fc encoding nucleic acids are expressed under the control of the GALl galactose-inducible promoter and in-frame with a nucleotide sequence encoding Aga2p, the mating agglutinin cell wall protein. In a preferred embodiment, nucleic acids encoding molecules comprising Fe regions are cloned C-terminal to the Aga2p coding region, such that a Fe-region Aga2p fusion protein is encoded. A fusion protein comprising the Aga2p protein and polypeptides comprising Fe regions will be secreted extracellularly and displayed on the cell wall via disulfide linkage to the Agalp protein, an integral cell wall protein, using the preferred construct of the invention. In an alternative embodiment, the constructs may further comprise nucleotide sequences encoding epitope tags. Any epitope tag nucleotide coding sequence known to those skilled in the art can be used in accordance with the invention, including, but not limited to nucleotide sequences encoding hemagglutinin (HA), c-myc Xpress TAG, His - TAG, or V5TAG. The presence of the fusion protein on the yeast cell surface may be detected using FAGS analysis, confocal fluorescence microscopy or standard inununostaining methods, all of which are known to those skilled in the art. In one embodiment, the presence of the Fe fusion proteins of the invention on the yeast cell surface are detected using Fe-specific monoclonal antibodies (CH3 specific), including but not limited to IgGl Fe-specific monoclonal antibody, HP6017 (Sigma), JL512 (Immunotech), and any antibody disclosed in Partridge et al., 1986, Mo!ecu!ar Immuno!ogy, 23 (12): 1365-72, which is incorporated herein by reference in its entirety. In another embodiment, the presence of the Fe fusion proteins of the invention are detected by immunofluorescent labeling of epitope tags using techniques known to those skilled in the art. It is particularly useful in the methods of the invention, to use nucleotide sequences encoding epitope tags to flank the nucleic acids encoding the Fe fusion proteins, as an internal control, to detect if the fusion proteins are displayed on the cell wall in a partially proteolyzed form. [00292] The invention encompasses screening the yeast display libraries using immunological based assays including but not limited to cell based assays, solution based assays, and solid phase based assays. [002931 In some embodiments, the invention encompasses identification of Fe mutants with altered FcR affinities using affinity maturation methods which are known to those skilled in the art and encompassed herein. Briefly, affinity maturation creates novel alleles by randomly recombining individual mutations present in a mutant library, see, e.g., 226: 889-896; Stemmer etal., 1994 Nature, 370:389-91; both of which are incorporated herein by reference in their entireties. It has been used successfully to increase the affinity of antibodies, T cell receptors and other proteins. The invention encompasses using mutations that show increased FcR binding as a baseline to construct new mutant libraries with enhanced phenotypes. Using the methods of the invention, a population of IgGl Fc mutants enriched by yeast surface display for increased binding to an FcyR, e.g., FcRIBA, may be selected. Following DNA preparation, Fe regions can be amplified by POR using flanking primers that selectively amplify the mutated region of the Fe, which is about —700 bp using methods known to one skilled in the art and exemplified or disclosed herein. Novel mutants can thus be constructed by reshuffling of mutations in the Fe region for example via DNAseI treatment of the amplified DNA and isolation of fragments using methods such as those disclosed by Stemmer eta!., 1994 Proc. Nat!. Acad. Sci. USA 91: 10747-51, which is incorporated herein by reference in its entirety. Fragments can then be religated, PCR amplified with nested primers and cloned into the yeast display vector, e.g., pYDi using methods known to one skilled in the art. The recombined library can then be reselected in the yeast Fe display screen. As the KD decreases, below 10 nM, conditions can be established to allow for further increases in affinity based on the reduction of the off rate of the FcRIIIA ligand from the Fe receptor using methods known in the art such as those disclosed in Boder et as'., 1998, BiotechnoL Prog. 14:55-62, which is incorporated herein by reference in its entirety. The invention encompasses a kinetic screen of the yeast library. A kinetic screen may be established by labeling of the Fe displaying cells to saturation with a labeled ligand, e.g., a fluorescent ligand followed by incubation with an excess of non-labeled ligand for a predetermined period. After termination of the reaction by the addition of excess buffer (e.g., iX PBS, 0.5 mg/ml BSA) cells will be analyzed by FACS and sort gates set for selection. After each round of enrichment individual mutants can be tested for fold increases in affinity and sequenced for diversity. The in vifro recombination process can be repeated. In some embodimnets, the in vitro is repeated at least 3 times. [002941 Selection of the Fe variants of the invention may be done using any FcR including but not limited to polymorphic variants of FcR In some embodiments, selection of the Fe variants is done using a polymorphic variant of FcyR.TIIA which contains a phenylalanine at position 158. In other embodiments, selection of the Fe variants is done using a polymorphic variant of FcRIIIA which contains a valine at position 158. FcRliIA 158Y displays a higher affinity for IgGl than 158F and an increased ADCC activity (see, e.g., Koene etal., 1997, B!oo4 90:1109-14; Wu etaL, 1997, .1 Gun. Invest. 100:1059-70, rnrporated herein by reference in their entireties); this residue m tact directly interacts with the lower hinge region of IgGi as recently shown by IgGi-FcRIIIA co-crystallization studies, see, e.g., Sonderman eta!., 2000, Nature, 100: 1059-70, which is incorporated herein by reference in its entirety. Studies have shown that in some cases therapeutic antibodies have improved efficacy in FcyRIIIA-158V homozygous patients. For example, humanized anti-CD2O monoclonal antibody Rituximab was therapeutically more effective in FcyRIIIA158V homozygous patients compared to FcRIHA 158F homozygous patients (See, e.g., Cartron eta!., 2002 Blood, 99(3): 754-8). Although not intending to be bound by a particular mechanism of action, selection of Fe variants of the invention with FcRIiIA 158F allotype may provide for variants that once engineered into therapeutic antibodies will be clinically more efficacious for FcRIIIA 158F homozgous patients. [00295] The invention encompasses screening yeast libraries based on FcRIIB depletion and FcyRflIA selection so that Fe mutants are selected that not only have an enhanced affinity for FcRIIIIA but also have a reduced affinity for FcyRIIB. Yeast libraries may be enriched for clones that have a reduced affinity for FcyRIIB by sequential depletion methods, for example, by incubating the yeast library with magnetic beads coated with FcRIIB. FcyRflB depletion is preferrably carried out sequentially so that the library is enriched in clones that have a reduced affincity for Fc'RflB. In some embodiments, the FcRIIB depletion step results in a population of cells so that only 30% , preferably only 10%, more preferably only 5%, most preferably less than 1% bind FcRIIB. In some embodiments, FcRIIB depletion is carried out in at least 3 cycles, at least 4 cycles, at least 6 cycles. The FcyRIIB depletion step is preferrably combined with an FcRJIHA selection step, for example using FAGS sorting so that Fe variants with an enhanced affinity for FcRIIHA are selected. 5.2.5.1 FACS ASSAYS; SOLID PHASED ASSAYS AN]) IMMUNOLOGICAL BASED ASSAYS [00296] The invention encompasses characterization of the mutant Fe fusion proteins that are displayed on the yeast surface cell wall, according to the methods described in Section 5.2.3. One aspect of the invention provides a method for selecting mutant Fe fusion proteins with a desirable binding property, specifically, the ability of the mutant Fe fusion protein to bind FcRHIA and/or FcRIIA with a greater affinity than a comparable polypeptide comprising a wild-type Fe region binds FcyRflIA and/or FcRIIA. In another embodiment, the invention provides a method for selecting mutant Fe fusion proteins with a desirable binding property, specifically, the ability of the mutant Fe fusion protein to bind BaandA~rJkwRJIA with a greater affinity than a comparable polypeptide comprising a wild-type Fe region binds Fc'yRIIIA and/or FcRIIA, and further the ability of the mutant Fc fusion protein to bind FcRIIB with a lower affinity than a comparable polypeptide comprising a wild-type Fe region binds FcyRIIB. It will be appreciated by one skilled in the art, that the methods of the invention can be used for identifying and screening any mutations in the Fe regions of molecules, with any desired binding characteristic. [002971 Yeast cells displaying the mutant Fc fusion proteins can be screened and characterized by any biochemical or immunological based assays known to those skilled in the art for assessing binding interactions. [00298] Preferakly, fluorescence activated cell sorting (FACS), using any of the techniques known to those skilled in the art, is used for screening the mutant Fe fusion proteins displayed on the yeast cell surface for binding FcR.IIIA, preferably the FcRIHA tetrameric complex, or optionally FcRIIB. Flow sorters are capable of rapidiy examining a large number of individual cells that contain library inserts (e.g., 10-100 million cells per hour) (Shapiro et a!., Practical Flow Cytometry, 1995). Additionally, specific parameters used for optimization including, but not limited to, ligand concentration (i.e., FcRIIIA tetrameric complex), kinetic competition time, or FAGS stringency may be varied in order to select for the cells which display Fe fusion proteins with specific binding properties, e.g., higher affinity for FcRHIA compared to a comparable polypeptide comprising a wild-type Fe region. Flow cytorneters for sorting and examining biological cells are well known in the art. Known flow cytometers are described, for example, in U.S. Patent Nos. 4,347,935; 5,464,581; 5,483,469; 5,602,039; 5,643,796; and 6,211,477; the entire contents of which are incorporated by reference herein. Other known flow cytometers are the FACS Vantagem system manufactured by Becton Dickinson and Company, and the COPAS~' system manufactured by Union Biometrica. [00299] According to a preferred embodiment of the invention, yeast cells are analyzed by fluorescence activated cell sorting (FAGS). In most preferred embodiments, the FAGS analysis of the yeast cells is done in an iterative manner, at least twice, at least three times, or at least S times. Between each round of selection cells are regrown and induced so the Fe regions are displayed on the maxinum number of yeast cell surfaces. Although not intending to be bound by a particular mode of action, this iterative process helps enrich the population of the cells with a particular phenotype, e.g., high binding to FcRIIIA. [003001 In preferred embodiments, screening for Fe variants of the invention comprises a selection process that has multiple rounds of screening, e.g., at least two rounds reenin~mbodiment, screening for Fe variants that have an enhanced arnnity for FcRiIIA may comprise the following steps: in the first round of screening, a library of yeast cells, e.g., a naive library of l0~ cells is enriched by FAGS, preferably in an iterative manner, using for example labeled tetrameric FcRIIIA to select for Fc variants that have an enhanced affinity for FcyR.UIA; the variant Fc region that is selected with the desired phenotype, e.g., enhanced binding to FcRIIIA, is then introduced into an antibody, e.g., a 4-4-20 antibody, and the enginereed antibody is assayed using a secondary screen, e.g., ELISA for binding to an FcR. In the second round of screening, a single mutation library may be generated based on the first screen so that the Fe region harbors the variant displaying the enhanced affinity for FcRHIA; and enriched by FAGS using for example labeled monomeric FcRIJIA in both the presence and absence of unlabeled receptor; and the variant Fe region is then introduced into an antibody, e.g., a 4-4-20 antibody, and the enginereed antibody is assayed using a secondary screen, e.g., ELISA for binding to an FcR. In some embodiments, the secondary screen may further comprise characterizing the antibodies comprising Fe variants in an ADCC or BlAcore based assay using methods disclosed herein [003011 The invention encompasses FAGS screening of the mutant yeast library under equilibrium or kinetic conditions. When the screening is performed under equilibrium conditions, an excess of the yeast library carrying Fe mutants is incubated with FcRIIIA, preferably labeled FcRIiIA at a concentration 5-10 fold below the Kd, for at least one hour to allow binding of Fe mutants to FcRIIIA under equlibrium conditions. When the screening is performed under kinetic conditions, the mutant yeast library is incubated with labeled FcRIHA; the cells are then incubated with equimolar unlabeled FcR.IIIA for a pre-selected time, bound FcRilIA is then monitored. [00302] One exemplary method of analyzing the yeast cells expressing mutant Fe fusion proteins with FAGS is costaining the cells with FcRIIIA-tetrameric complex which has been labeled with a fluorescent label such as, PE and an anti-Fe antibody, such as F(ab)z anti-Fe which has been fluorescently labeled. Fluorescence measurements of a yeast library produced according to the methods of the invention preferably involves comparisons with controls; for example, yeast cells that lack the insert encoding molecules comprising an Fe region (negative control). The flow sorter has the ability not only to measure fluorescence signals in cells at a rapid rate, but also to collect cells that have specified fluorescent properties. This feature may be employed in a preferred embodiment of the invention to enrich the initial library population for cells expressing Fe fusion proteins with specific 4.g., higher affinity for Fc'RIJIA compared to a comparable polypeptide comprising a wild-type Fc region. In a preferred embodiment of the invention, yeast cells are analyzed by FAGS and sort gates established to select for cells that show the highest affinity for FcRIIIA relative to the amount of Fe expression on the yeast cell surface. According to a preferred embodiment, four consecutive sorts are established, wherein the gates for each successive sort is 5.5%, 1%, 0.2%, and 0.1%. It is preferred that the yeast display library formed according to the methods of the invention be over-sampled by at least 10-fold to improve the probability of isolating rare clones (e.g., analyze —40 cells from a library of ~ clones). Alternatively, 2-5 sorts are established to select for cells of the desired phenotype. Sort gates can be established empirically by one skilled in the art. [00303] In other preferred embodiments, mutant Fe fusion proteins displayed on the yeast cell surface are screened using solid phase based assays, for example assays using magnetic beads, e.g., supplied by Dynal, preferably in a high through put manner for binding to an FcR, e.g., FcRIIIA. In one embodiment, magnetic bead assays may be used to identify mutants with enhanced affinity for FcyRIIIA and/or reduced affinity for FcyRIIB. An exemplary assay to identify mutants with enhanced affinity for FcRIilA and reduced affinity for FcRIIB may comprise selecting mutants by a sequential solid phase depletion using magnetic beads coated with FcRflB followed by selection with magnetic beads coated with FcRIHA. For example one assay may comprise the following steps: incubating the library of yeast cells generated in accordance with the methods of the invention with magnetic beads coated with FcRIIB; separating yeast cells bound to beads from the non bound fraction by placing the mixture in a magnetic field, removing the non-bound yeast cells and placing them in a fresh media; binding the yeast cells to beads coated with FcRIIIA, separating yeast cells bound to beads from the non bound fraction by placing the mixture in a magnetic field, removing the non-bound yeast cells; removing the bound cells by rigorous vortexing; growing the recovered cells in glucose containing media; re-inducing in selective media containing galactose. The selection process is repeated at least once. Inserts containing the Fe domain are then amplified using common methodologies known in the art, e.g., PGR, and introduced into an antibody by methods already described for further characterization. [003041 In an alternative embodiment, a non-yeast based system is used to characterize the binding properties of the molecules of the invention. One exemplary system for characterizing the molecules of the invention comprises a mammalian expression vector containing the heavy chain of the anti-fluorescein monoclonal antibody 4-4-20, into the molecules of the invention with variant Fe regions are cloned. The resulting recombinant clone is expressed in a mammalian host cell line (i.e., human kidney cell line 29311), and the resulting recombinant immunoglobulin is analyzed for binding to FcR using any standard assay known to those in the art, including but not limited to ELISA and FAGS. [00305] Molecules of the present invention (e.g., antibodies, fusion proteins, conjugated molecules) may be characterized in a variety of ways. In particular, molecules of the invention comprising modified Fe regions may be assayed for the ability to immunospecifically bind to a ligand, e.g., FcRIIIA tetrameric complex. Such an assay may be performed in solution (e.g., Houghten, BiofTechniques, 13:412-421, 1992), on beads (Lam, Nature, 3 54:82-84, 1991, on chips (Fodor, Nature, 364:555-556, 1993), on bacteria (U.S. Patent No. 5,223,409), on spores (U.S. Patent Nos. 5,571,698; 5,403,484; and 5,223,409), on plasmids (Cull etal., Proc. Nat!. Acad Sci. USA, 89:1865-1869, 1992) or on phage (Scott and Smith, Science, 249:386-390, 1990; Devlin, Science, 249:404-406, 1990; Gwirla et al., Proc. Natl. A cad. Sci. USA, 87:6378-63 82, 1990; and Felici, .1. Mo!. Bios'., 222:301-310, 1991) (each of these references is incorporated by reference herein in its entirety). Molecules that have been identified to inimunospecifically bind to an ligand, e.g., FcyRIIIA can then be assayed for their specificity and affinity for the ligand. [00306] Molecules of the invention that have been engineered to comprise modified Fe regions (e.g., therapeutic antibodies) or have been identified in the yeast display system to have the desired phenotype (see Section 5.1) may be assayed for immunospecific binding to an antigen (e.g., cancer antigen and cross-reactivity with other antigens (e.g., FcR) by any method knQwn in the art. Immunoassays which can be used to analyze immunospecific binding and cross-reactivity include, but are not limited to, competitive and non-competitive assay systems using techniques such as western blots, radioimmunoassays, ELISA (enzyme linked innnunosorbent assay), "sandwich" inimunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, inimunoradiometric assays, fluorescent immunoassays, protein A immunoassays, to name but a few. Such assays are routine and well known in the art (see, e.g., Ausubel etal., eds, 1994, Current Protocols in Molecular Biology, Vol. 1, John Wiley & Sons, Inc., New York, which is incorporated by reference herein in its entirety). [00307] The binding affinity of the molecules of the present invention comprising modified Fe regions to a ligand, e.g., FcR tetrameric complex and the off-rate of the interaction can be determined by competitive binding assays. One example of a competitive comprising the incubation of labeled ligand, such as tetrameric FcR (e.g., ~H or 1251) with a molecule of interest (e.g., molecules of the present invention comprising modified Fe regions) in the presence of increasing amounts of unlabeled ligand, such as tetrameric Fc7R, and the detection of the molecule bound to the labeled ligand. The affinity of the molecule of the present invention for the ligand and the binding off-rates can be determined from the saturation data by scatchard analysis. [00308] In a preferred embodiment, BIAcore kinetic analysis is used to determine the binding on and off rates of molecules of the present invention to a ligand such as FcR. BlAcore kinetic analysis comprises analyzing the binding and dissociation of a ligand from chips with immobilized molecules (e.g., molecules comprising modified Fe regions) on their surface. 5.2.6 SEQUENCING OF MUTANTS [00309] Any of a variety of sequencing reactions known in the art can be used to directly sequence the molecules of the invention comprising variant Fe regions. Examples of sequencing reactions include those based on techniques developed by Maxim and Gilbert (Proc. Nat!. AcadJ Sci. USA, 74:560, 1977) or Sanger (Proc. NatL Acad. Sci. USA, 74:5463, 1977). It is also contemplated that any of a variety of automated sequencing procedures can be utilized (Bio/TT'echniques, 19:448, 1995), including sequencing by mass spectrometry (see, e.g., POT Publication No. WO 94/16101, Cohen et al.,Adv. Chromatogr., 36:127-162, 1996, and Griffin etal,, Appl. Biochem. Biotechnol., 38:147-159, 1993). 5.2.7 FUNCTIONAL ASSAYS OF MOLECULES WITH VAIUANT Fc REGIONS [00310] The invention encompasses characterization of the molecules of the invention (e.g., an antibody comprising a variant Fe region identified by the yeast display technology described supra; or therapeutic monoclonal antibodies engineered according to the methods of the invention) using assays known to those skilled in the art for identifying the effector cell function of the molecules. In particular, the invention encompasses characterizing the molecules of the invention for FcR-mediated effector cell function. Examples of effector cell functions that can be assayed in accordance with the invention, include but are not limited to, antibody-dependent cell mediated cytotoxicity, phagocytosis, opsonization, opsonophagocytosis, Clq binding, and complement dependent cell mediated cytotoxicity. Any cell-based or cell free assay known to those skilled in the art for determining effector cell function activity can be used (For effector cell assays, see Perussia etal., 2000,MethodsMoL Biol 121:179-92; Baggiolini etat, 1998 Experientla~ 44(10): J~ Immunol. Methods, 243(1 -2): 229-42; Brown EJ. 1994, Methods Cell Biol, 45: 147-64; Munn eta!., 1990 J. Exp. Med, 172: 231-237, Abdul-Majid etal., 2002 Scand .1 linmuno!. 55: 70-81; Ding eta!., 1998, Immunity 8:403-411, each of which is incorporated by reference herein in its entirety). [00311] In one embodiment, the molecules of the invention can be assayed for FcR¬mediated phagocytosis in human monocytes. Alternatively, the FcR-mediated phagocytosis of the molecules of the invention may be assayed in other phagocytes, e.g., neutrophils (polymorphonuclear leuckocytes; PMN); human peripheral blood monocytes, monocyte-derived macrophages, which esi be obtained using standard procedures known to those skilled in the art (e.g., see Brown EJ. 1994, Methods Cell Bios'., 45:147-164). In one embodiment, the function of the molecules of the inventiQn is characterized by measuring the ability of THP-l cells to phagocytose fluoresceinated IgG-opsonized sheep red blood cells (SR.BC) by methods previously described (Tridandapani et al., 2000, J. Biol. Chem. 275: 20480-7). For example,. an exemplary assay for measuring phagocytosis of the molecules of the invention comprising variant Fe regions with enhanced affinities for FcRIIIA, comprises of: treating THP-l cells with a molecule of the invention or with a control antibody that does not bind to FcRJUA, comparing the activity levels of said cells, wherein a difference in the activities of the cells (e.g., rosetting activity (the number of THP-l cells binding IgG-coated SRI3C), adherence activity (the total number of SRBC bound to THP-l cells), and phagocytic rate) would indicate the functionality of the molecule of the invention. It can be appreciated by one skilled in the art that this exemplary assay can be used to assay any of the molecules identified by the methods of the invention. [00312] Another exemplary assay for determining the phagocytosis of the molecules of the invention is an antibody-dependent opsonophagocytosis assay (ADOP) which can comprise the following: coating a target bioparticle such as Escherichia coli-labeled FITO (Molecular Probes) or Staphylococcus aureus-FITG with (i) wild-type 4-4-20 antibody, an antibody to fluorescein (See Bedzyk eta!, 1989, J. BIos'. Chem, 264(3): 1565-1569, which is incorporated herein by reference in its entirety), as the control antibody for FcR¬dependent ADCP; or (ii) 4-4-20 antibody harboring the D265A mutation that knocks out binding to FcRTil, as a background e~ntrol for FcR-dependent ADCP (ill) 4-4-20 antibody carrying variant Fe regions identified by the methods of the invention and produced as exemplified in Example 6.6; and forming the opsonized particle; adding any of the osponized particles described (i-iii) to THP-l effector cells (a monocytic ceU line available from ATOG) in a 60:1 ratio to allow FcR-mediated phagocytosis to ~ii~; preferably incubating the cells and E. co!i-FITC/antibody at 370C for 1.5 hour; adding rr~Lue4tieu incubation (preferably at room temperature for 2-3 mm.) to the cells to quench the fluoroscence of the bacteria that are adhered to the outside of the cell surface without being internalized; transfering cells into a FAGS buffer (e.g., 0.1%, BSA in PBS, 0.1%, sodium azide), analyzing the fluorescence of the THP1 cells using FAGS (e.g., BD FAGS Calibur). Preferably, the THP-l cells used in the assay are analyzed by FAGS for expression of Fc'yR on the cell surface. THF-l cells express both GD32A and CD64. CD64 is a high affinity FcR that is blocked in conducting the ADGP assay in accordance with the methods of the invention. The THP-l cells are preferably blocked with 100 ~g/mL soluble IgGl or 10% human serum. To analyze the extent of ADOP, the gate is preferably set on THP-1 cells and mediap fluorescence intensity is measured. The ADOP activity for individual mutants is calculated and reported as a normalized value to the wild type chMab 4-4-20 obtained. The opsonized particles are added to THP-l cells such that the ratio of the opsonized particles to TI{P-l cells is 30:1 or 60:1. In most preferred embodiments, the ADCP assay is conducted with controls, such as E. coli-FITC in medium, E. coli-FITC and THP-1 cells (to serve as Fc~yR-independent ADCP activity), E. coli-FITC, THP-l cells and wild-type 4-4-20 antibody (to serve as FcR-dependent ADOP activity), E co!i-FITC, THP¬1 cells, 4-4-20 D265A (to serve as the background control for FcR-dependent ADCP activity). [00313] In another embodiment, the molecules of the invention can be assayed for FcR-mediated ADGG activity in effector cells, e.g., natural killer cells, using any of the standard methods known to those skilled in the art (See e.g., Perussia eta!., 2000, Methods Mol Bios'. 121:179-92). An exemplary assay for determining ADOC activity of the molecules of the invention is based on a 51Cr release assay comprising of: labeling target cells with [51Gr]Na2CrOA (this cell-membrane permeable molecule is commonly used for labeling since it binds cytoplasmic proteins and although spontaneously released from the cells with slow kinetics, it is released massively following target cell necrosis); osponizing the target cells with the molecules of the invention comprising variant Fe regions; combining the opsonized radiolabeled target cells with effector cells in a microtitre plate at an appropriate ratio of target cells to effector cells; incubating the mixture of cells for 16-18 hours at 3700; collecting supernatants; and analzying radioactivity. The cytotoxicity of the molecules of the invention can then be determined, for example using the following formula: % lysis = (experimental cpm - target leak cpm)/(detergent lysis epra - target leak cpm) x 100%. Alternatively, % lysis (ADCC-AICG)/(maximum release-spontaneous release). Specific lysis can be calculated using the formula: specific lysis = % lysis with the molecules of the invention - % lysis in the absence of the molecules of the invention. A be~taerated-by varying either the target: effector cell ratio or antibody concentration. [00314] In yet another embodiment, the molecules of the invention are characterized for antibody dependent cellular cytotoxicity (ADGO) see, e.g., Ding etal., Immunity, 1998, 8:403-11; which is incorporated herein by reference in its entirety. [00315] Preferably, the effector cells used in the ADOG assays of the invention are peripheral blood mononuclear cells (PDMG) that are preferably purified from normal human blood, using standard methods known to one skilled in the art, e.g., using Ficoll¬Paque density gradient centrifugation. Preferred effector cells for use in the methods of the invention express different FcR activating receptors. The invention encompasses, effector cells, THP-l, expressing FcyR.I, FcRUA and FcRIIB, and monocyte derived primary macrophages derived from whole human blood expressing both FcRIIIA and FcyRIlB, to determine if Fe antibody mutants show increased ADOC activity and phagocytosis relative to wild type IgGl antibodies. [003161 The human monocyte cell line, TI(P-l, activates phagocytosis through expression of the high affinity receptor FcRI and the low affinity receptor FcRIIA (Fleit et al., 1991, 1. Leuk. Biol. 49: 556). T.HP-l cells do not constitutively express FcRIIA or FcRTIB. Stimulation of these cells with cytokines effects the FcR expression pattern (Pricop et aL, 2000 J. humunol. 166: 53 1-7). Growth of THP-l cells in the presence of the cytokine 1L4 induces FcRIIB expression and causes a reduction in FcRIIA and FcyRI expression. FcRIiB expression can also be enhanced by increased cell density (Tridandapani etal., 2002, J. Biol Chem. 277: 5082-9). In contrast, it has been reported that IFNy can lead to expression of FcRILIA (Pearse eta!., 1993 PNAS USA 90: 43 14-8). The presence or absence of receptors on the cell surface can be determined by FAGS using common methods known to one skilled in the art. Cytokine induced expression of FcR on the cell surface provides a system to test beth activation and inhibition in the presence of FcRIIB. If THP-l cells are unable to express the FcRJIB the invention also encompasses another human monocyte cell line, U937. These cells have been shown to terminally differentiate into macrophages in the presence of IFNy and TNF (Koren et aL, 1979, Nature 279: 328-331). [00317] FcR dependent tumor cell killing is mediated by macrophage and NK cells in mouse tumor models (Clynes et aL, 1998, PNAS USA 95: 652-656). The invention encompasses the use of elutriated monocytes from donors as effector cells to analyze the efficiency Fe mutants to trigger cell cytotoxicity of target cells in both phagocytosis and patterns of FcRT, FcRiIIA, and FcRIIB are affected by different growth conditions. FcR expression from frozen elutriated monocytes, fresh elutriated monocytes, monocytes maintained in 10% EBS, and monocytes cultured in FBS + GM-GSF and or in human serum may be determined using common methods known to those skilled in the art. For example, cells can be stained with FcR specific antibodies and analyzed by FAGS to determine FcR profiles. Conditions that best mimic macrophage in vivo FcR expression is then used for the methods of the invention. [003181 In some embodiments, the invention encompasses the use of mouse cells especially when human cells with the right FcR profiles are unable to be obtained. In some embodiments, the invention encompasses the mouse macrophage cell line RAW264.7(ATCG) which can be transfected with human FcRIIIA and stable transfectants isolated using methods known in the art, see, e.g., Ralph eta., J. Immuno!. 119:950-4). Transfectants can be quantitated for FcRIIIA expression by FAGS analysis using routine experimentation and high expressors can be used in the ADOC assays of the invention. In other embodiments, the invention encompasses isolation of spleen peritoneal macrophage expressing human FcR from knockout transgenic mice such as those disclosed herein. [003191 Lymphocytes may be harvested from peripheral blood of donors (PBM) using a Ficoll-Paque gradient (Pharmacia). Within the isolated mononuclear population of cells the majority of the ADOC activity occurs via the natural killer cells (NK) containing FcRIIIA but not FcR.ITB on their surface. Results with these cells indicate the efficacy of the mutants on triggering NK cell ADOG and establish the reagents to test with elufriated monocytes. [00320] Target cells used in the ADOC assays of the invention include, but are not limited to, breast cancer cell lines, e.g., SK-BR-3 with ATOC aceession number HTB-30 (see, e.g., Tremp eta!., 1976, Cancer Res. 33-41); B-lymphocytes; cells derived from Burkitts lymphoma, e.g., Raji cells with ATOG accession number GGL-86 (see, e.g., Epstein et a!., 1965, J. Nat!. Cancer Inst. 34: 231-240), and Daudi cells with ATOG accession number GCL-213 (see, e.g., Klein eta!., 1968, Cancer Res. 28:1300-10). The target cells must be recognized by the antigen binding site of the immunoglobulin to be assayed. [00321] The ADGO assay is based on the ability of NK cells to mediate cell death via an apoptotic pathway. NK cells mediate cell death in part by FcRIIIA's recognition of IgG bound to an antigen on a cell surface. The ADOC assays used in accordance with the methods of the invention may be radioactive based assays or fluorescence based assays. ~p characterize the molepules of the invention comprising variant Fc regions comprises labeling target cells, e.g., SK-BR-3, MGF-7, OVGAR3, Raji, Daudi cells, opsonizing target cells with an antibody that recognizes a cell surface receptor on the target cell via its antigen binding site; combining the labeled opsonized target cells and the effector cells at an appropriate ratio, which can be determined by routine experimentation; harvesting the cells; detecting the label in the supernatant of the lysed target cells, using an appropriate detection scheme based on the label used. The target cells may be labeled either with a radioactive label or a fluorescent label, using standard methods known in the art. For example the labels include, but are not limited to, [51Gr]Na2GrO4; and the acetoxymethyl ester of the fluorescence enhancing ligand, 2,2':6',2"-terpyridine-6-6"-dicarboxylate (TDA). (093221 In a specific preferred embodiment, a time resolved fluorimetric assay is used for measuring ADCG activity against target cells that have been labeled with the acetoxymethyl ester of the fluorescence enhancing ligand, 2,2':6',2"-terpyridine-6-6"-dicarboxylate (TDA). Such fluorimetric assays are known in the art, e.g., see, Blomberg et a!., 1996, Journal of Immunologica! Methods, 193: 199-206; which is incorporated herein by reference in its entirety. Briefly, target cells are labeled with the membrane permeable acetoxymethyl diester of TDA (bis(acetoxymethyl) 2,2' :6',2"-terpyridine-6-6"-dicarboxylate, (BATDA), which rapidly diffuses across the cell membrane of viable cells. Intracellular esterases split off the ester groups and the regenerated membrane impermeable TDA molecule is trapped inside the cell. After incubation of effector and target cells, e.g., for at least two hours, up to 3.5 hours, at 370C, under 5% C02, the WA released from the lysed target cells is chelated with Eu3+ and the fluorescence of the Europium-TDA chelates formed is quantitated in a time-resolved fluorometer (e.g., Victor 1420, Perkin Elmer/Wallac). [003231 In another specific embodiment, the ADGC assay used to characterize the molecules of the invention comprising variant Fe regions comprises the following steps: Preferably 4-5x 106 target cells (e.g., SK-BR-3, MGF-7, OVCAR.3, R.aji cells) are labeled with bis(acetoxymethyl) 2,2':6',2"-terpyridine-t-6"-dicarboxylate (DELFIA BATDA Reagent, Perkin Elmer/Wallac). For optimal labeling efficiency, the number of target cells used in the ADCC assay should preferably not exceed 5x106. BAThA reagent is added to the cells and the mixture is incubated at 370d preferably under 5% GO2, for at least 30 minutes. The cells are then washed with a physiological buffer, e.g., PBS with 0.125 mM sulfinpyrazole, and media containing 0.125 mM sulfinpyrazole. The labeled target cells are then opsonized (coated) with a molecule of the invention comprising a variant Fe region, a variant Fe region of the invention, including, but not limited to, a polyclonal antibody, a monoclonal antibody, a bispecific antibody, a multi-specific antibody, a humanized antibody, or a chimeric antibody. In preferred embodiments, the immunoglobulin comprising a variant Fe region used in the ADOG assay is specific for a cell surface receptor, a tumor antigen, or a cancer antigen. The inimunoglobulin into which a variant Fe region of the invention is introduced may specifically bind any cancer or tumor antigen, such as those listed in section 5.4. Additionally, the immunoglobulin into which a variant Fe region of the invention is introduced may be any therapeutic antibody specific for a cancer antigen, such as those listed in section 5.4. In some embodiments, the immunoglobulin comprising a variant Fe region used in the ADGO assay is an anti-fl~ioresceine monoclonal antibody, 4-4-20 (Kranz etal, 1982 J~ Bios'. Chem~ 257(12): 6987-6995) a mouse-human chimeric anti-CD2O monoclonal antibody 2117 (Liu et a!., 1987, Journa! oflmmuno!ogy, 139: 3521-6); or a humanized antibody (Ab4DS) against the human epidermal growth factor receptor 2 (p185 1{ER2) (Carter et a!. (1992, Proc. Nat!. Acad Sci. USA 89: 4285-9). The target cells in the ADCG assay are chosen according to the immunoglobulin into which a variant Fe region of the invention has been introduced so that the immunogiobulin binds a cell surface receptor of the target cell specifically. Preferably, the ADGG assays of the invention are performed using more than one engineered antibody, e.g., anti Her2/neu, 4-4-20, 2B6, Rituxan, and 2117, harboring the Fe variants of the invention. In a most preferred embodiment, the Fe variants of the invention are introduced into at least 3 antibodies and their ADGG activities are tested. Although not intending to be bound by a particular mechanism of action, examining at least 3 antibodies in these functional assays will diminish the chance of eliminating a viable Fe mutation erroneously. [00324] Opsonized target cells are added to effector cells, e.g., PBMC, to produce effector:target ratios of approximately 50:1, 75:1, or 100:1. In a specific embodiment, when the immunoglobulin comprising a variant Fe region has the variable domain of 4-4-20, the effector:target is 75:1. The effeetor and target cells are incubated for at least two hours, up to 3.5 hours, at 370C, under 5% CO2. Cell supematants are harvested and added to an acidic europium solution (e.g., DELFIA Europium Solution, Perkin Elmer/Wallac). The fluorescence of the Europium-WA chelates formed is quantitated in a time-resolved fluorometer (e.g., Victor 1420, Perkin Elmer/Wallac). Maximal release (MR) and spontaneous release (SR) are determined by incubation of target cells with 1% TX-100 and media alone, respectively. Antibody independent cellular cytotoxicity (AICO) is measured by incubation of target and effeetor cells in the absence of antibody. Each assay is The mean percentage specific lysis is calculated as: Experimental release (ADCG) - AIGG)/(MR-SR) x 100. (00325] The invention encompasses characterization of the Fc variants in both NK¬dependent and macrophage dependent ADCC assays. Fe variants of the invention have altered phenotypes such as an altered effector function as assayed in an NK dependent or macrophage dependent assay. [003261 The invention encompasses assays known in the art and exemplified herein, to bind Clq and mediate complement dependent cytotoxicity (CDG). To determine Clq binding, a Glq binding ELISA may be performed. An exemplary assay may comprise the following: assay plates may be coated overnight at 4G with polypeptide variant or starting polypeptide (control) in coating buffer. The plates may then be washed and blocked. Following washing, an aliquot of human Clq may be added to each well and incubated for 2 hrs at room temperature. Following a further wash, 100 µL of a sheep anti-complement Clq peroxidase conjugated antibody may be added to each well and incubated for 1 hour at room temperature. The plate may again be washed with wash buffer and 100 ul of substrate buffer containing OPD (0-phenylenediamine dihydrochloride (Sigma)) may be added to each well. The oxidation reaction, observed by the appearance of a yellow color, may be allowed to proceed f~r 30 minutes and stopped by the addition of 100 ul of 4.5 NH2 504. The absorbance may then read at (492-405) nm. 100327] A preferred variant in accordance with the invention is one that displays a significant reduction in Clq binding, as detected and measured in this assay or a similar assay. Preferably the molecule comprising an Fe variant displays aboi~t 50 fold reduction, about 60 fold, about 80 fold, or about 90 fold reduction in Clq binding compared to a control antibody having a nonmutated IgGI Fe region. In the most preferred embodiment, the molecule comprising an Fe variant does not bind Glq, i.e. the variant displays about 100 fold or more reduction in Clq binding compared to the control antibody. [00328] Another exemplary variant is one which has a better binding affinity for human Clq than the molecule comprising wild type Fe region. Such a molecule may display, for example, about two-fold or more, and preferably about five-fold or more, improvement in human Clq binding compared to the parent molecule comprising wild type Fe region. For example, human Glq binding may be about two-fold to about 500-fold, and preferably from about two-fold or from about five-fold to about 1000-fold improved compared to the molecule comprising wild type Fe region. [003291 To assess complement activation, a complement dependent cytotoxicity (ODO) assay may be performed, e.g. as described in Gazzano-Santoro et al., J. Immunol. which is incorporated herein by reference in its entirety. l3rietly, various concentrations of the molecule comprising a variant Fe region and human complement may be diluted with buffer. Cells which express the antigen to which the molecule comprising a variant Fe region binds may be diluted to a density of about 1x106 cells/mI. Mixtures of the molecule comprising a variant Fe region, diluted human complement and cells expressing the antigen may be added to a flat bottom tissue culture 96 well plate and allowed to incubate for 2 hrs at 37G. and 5% C02 to facilitate complement mediated cell lysis. 50 µL of alamar blue (Accumed International) may then be added to each well and incubated overnight at 37 C. The aksorbance is measured using a 96-well fluorometer with excitation at 530 nm and emission at 590 µm. The results may be expressed in relative fluorescence ux~its (RFU). The sample concentrations may be computed from a standard curve and the percent activity as compared to nonvariant molecule, i.e., a molecule comprising wild type Fe region, is reported for the variant of interest. (003301 In some embodiments, an Fc variant of the invention does not activate complement Preferably the variant does not appear to have any CDG activity in the above CDC assay. The invention also pertains to a variant with enhanced CDC compared to a parent molecule (a molecule comprising wild type Fe region), e.g., displaying about two¬fold to about 100-fold improvement in GDG activity in vitro or in vivo (e.g., at the IGSO values for each molecule being compared). Complement assays may be performed with guinea pig, rabbit or human serum. Complement lysis of target cells may be detected by monitoring the release of intracellular enzymes such as lactate dehydrogenase (LDH), as described in Korzeniewski et aL, 1983 Immuno!. Methods 64(3): 3 13-20; and Decker et as'., 1988 JJ Immuno! Methods 115(1): 61-9, each of which is incorporated herein by reference in its entirety; or the release of an intracellular lable such as europium, chromium 51 or indium 111 in which target cells are labeled as described herein. [00331] The molecules of the invention comprising variant Fe regions may also be assayed using any surface plasmon resonance based assays known in the art for characterizing the kinetic parameters of Fe-FcR interaction binding. Any SPR instrument commercially available including, but not limited to, BlAcore Instruments, available from Biacore AB (Uppsala, Sweden); lAsys instruments available from Affinity Sensors (Franklin, MA.); IBIS system available from Windsor Scientific Limited (Berks, UK), SPR¬CELLIA systems available from Nippon Laser and Electronics Lab (Hokkaido, Japan), and from Texas Instruments (Dallas, TX) can be used m the instant invention. For a review of SPR-based technology see Mullet et a!., 2000, Methods 22: 77-91; Dong eta!., 2002, Review in Mol. Biotech., 82: 303-23; Fivash eta!., 1998, Current Opinion in Biotechnology 9: 97-101; Rich et a!., 2000, Current Opinion in Biotechnos'ogy 11: 54-61; all of which are incorporated herein by reference in their entirety. Additionally, any of the SPR instruments and SPR based methods for measuring protein-protein interactions described in U.S. Patent No.'s 6,373,577; 6,289,286; 5,322,798; 5,341,215; 6,268,125 are contemplated inthe methods of the invention, all of which are incorporated herein by reference in their entirety. [00332] briefly, SPR based assays involve immobilizing a member of a binding pair on a surface, and monitoring its interaction with the other member of the binding pair in solution in real time. SPR is based on measuring the change in refractive index of the solvent near the surface that occurs upon complex formation or dissociation. The surface onto which the immobilization occur is the sensor chip, which is at the heart of the SPR technology; it consists of a glass surface coated with a thin layer of gold and forms the basis for a range of specialized surfaces designed to optimize the binding of a molecule to the surface. A variety of sensor chips are commercially available especially from the companies listed supra, all of which may be used in the methods of the invention. Examples of sensor chips include those available from BlAcore AB, Inc., e.g., Sensor Chip CM5, SA, NTA, and ILPA. A molecule of the invention may be immobilized onto the surface of a sensor chip using any of the immobilization methods and chemistries known in the art, including but not limited to, direct covalent coupling via amine groups, direct covalent coupling via sulfhydryl groups, biotin attachment to avidin coated surface, aldehyde coupling to carbohydrate groups, and attachment through the histidine tag with NTA chips. [003331 In some embodiments, the kinetic parameters of the binding of molecules of the invention comprising variant Fe regions, e.g., immunoglobulins comprising variant Fe region, to an FcyR may be determined using a BlAcore instrument (e.g., BIAcore instrument 1000, BlAcore Inc., Piseataway, NJ). Any FcR can be used to assess the interaction with the molecules of the invention comprising variant Fe regions. In a specific embodiment the FcR is FcRIIIA, preferably a soluble monomeric FcRIIIA. For example, in one embodiment, the soluble monomeric FcyR.IIIA is the extracellular region of FcRflIA joined to the linker-A VITAG sequence (see, U.S. Provisional Application No. 60/439,498, filed on January 9,2003 (Attorney Docket No. 11183-004-888) and U.S. Provisional Application No. 60/456,041 filed on March 19,2003, which are incorporated In another specific embodiment, the FcR is FcRIIB, preferably a soluble dimeric FcRIIB. For example in one embodiment, the soluble dimeric FcyRIIB protein is prepared in accordance with the methodology described in U.S. Provisional application No. 60/439,709 filed on January 13, 2003, which is incorporated herein by reference in its entirety. [003341 An exemplary assay for determining the kinetic parameters of a molecule comprising a variant Fe region, wherein the molecule is the 4-4-20 antibody, to an FcR using a BlAcore instrument comprises the following: BSA-FITC is inimobilized on one of the four flow cells of a sensor chip surface, preferably through amine coupling chemistry such that about 5000 response units (RU) of flSA-FITG is immobilized on the surface. Once a suitable surface is prepared, 4-4-20 antibodies carrying the Fe mutations are passed over the surface, preferably by one minute injections of a 20 pg/mL solution at aS jiL/mL flow rate. The level of 4-4-20 antibodies bound to the surface ranges between 400 and 700 RU. Next, dilution series of the receptor (FcRIIA and FcRIIB-Fe fusion protein) in HBS¬P buffer (20mM HEPES, 150 mMNaCl, 3niM EDTA, pH 7.5) are injected onto the surface at 100 pL/min Antibody regeneration between different receptor dilutions is carried out preferably by single 5 second injections of 100mM NaHCO3 pH 9.4; 3MNaGl. Any regeneration technique known in the art is contemplated in the method of the invention. [00335] Once an entire data set is collected, the resulting binding curves are globally fitted using computer algorithms supplied by the SPR instrument manufacturer, e.g., BlAcore, Inc. (Piscataway, NJ). These algorithms calculate both the ~ and K~, from which the apparent equilibrium binding constant, Kd is deduced as the ratio of the two rate constants (i.e., K0~/K~,~). More detailed treatments of bow the individual rate constants are derived can be found in the BlAevaluaion Software Handbook (BIAcore, Inc., Piscataway, NJ). The analysis of the generated data may be done using any method known in the alt For a review of the various methods of interpretation of the kinetic data generated iee Myszka, 1997, Current Opinion in Biotechnology 8: 50-7; Fisher eta!., 1994, Current Opinion in Blotechno!ogy 5:389-95; O'Shannessy, 1994, current Opinion in Biotechnology, 5:65-71; Chaiken eta!., 1992, Analytical BiochemIstry, 201:197-210; Morton et as'., 1995, Analytical Biochemistry 227:176-85; O'Sbannessy eta!., 1996, Analytical Biochemistry 236:275-83; all of which are incorporated herein by reference in their entirety. [00336] In preferred embodiments, the kinetic parameters determined using an SPR analysis, e.g., BlAcore, may be used as a predictive meaure of how a molecule of the invention will function in a functional assay, e.g., ADOC. An exemplary method for a molecule of the invention based on kinetic parameters obtained from an SPR analysis may comprise the following: determining the K0ff values for binding of a molecule of the invention to FcyR.IIIA and FcyRIIB; plotting (1) K~,r.~(wt)/K~,g (mut) for FcRilIA; (2) K0ff (mut)/Koff (wt) for FcRIIB against the ADCC data. Numbers higher than one show a decreased dissociation rate for FcR.IIIA and an increased dissociation rate for FcyRIIB relative to wild tyoe; and possess and enhanced ADCC function. 5.3 METHODS OF RECOMBINANTLY PRODUCING MOLECULES OF THE INVENTION 5.3.1 POLYNUCLEOTIDES ENCODING MOLECULES QF THE INVENTION [00337] The present invention also includes polynucleotides that encode the molecules, including the polypeptides and antibodies, of the invention identified by the methods of the invention. The polynucleotides encoding the molecules of the invention may be obtained, and the nucleotide sequence of the polynucleotides determined, by any method known in the art. [00338] Once the nucleotide sequence of the molecules (e.g., antibodies) that are identified by the methods of the invention is determined, the nucleotide sequence may be manipulated using methods well known in the art, e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et a!., 2001, Molecular Cloning. A Laboratory Manual 3rd Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, NY; and Ausubel eta!., eds., 1998, Current Protocols in Molecular Bioloay. John Wiley & Sons, NY, which are both incorporated by reference herein in their entireties), to generate, for example, antibodies having a different amino acid sequence, for example by generating amino acid substitutions, deletions, and/or insertions. [00339] In a specific embodiment, when the nucleic acids encode antibodies, one or more of the CDRs are inserted within framework regions using routine recombinant DNA techniques. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et a!., 1998, £ Mo!. Biol. 278: 457-479 for a listing of human framework regions). [00340] In another embodiment, human libraries or any other libraries available in the art, can be screened by standard techniques known in the art, to clone the nucleic acids encoding the molecules of the invention. COMBINANT EXPRESSION OF MOLECULES OF THE INVENTION [003411 Once a nucleic acid sequence encoding molecules of the invention (i.e., antibodies) has been obtained, the vector for the production of the molecules may be produced by recombinant DNA technology using techniques well known in the art. Methods which are well known to those skilled in the art can be used to construct expression vectors containing the coding sequences for the molecules of the invention and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. (See, for example, the techniques described in Sambrook eta!., 1990, Molecular Cloning. A Laboratory Manual. 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, NY an4 Ausubel eta!. eds., 1998, Current Protocols in Molecular Bioloav. John Wiley & Sons, NY). [00342] An expression vector comprising the nucleotide sequence of a molecule identified by the methods of the invention (i.e., an antibody) can be transferred to a host cell by conventional techniques (e.g., electroporation, liposomal transfection, and calcium phosphate precipitation) and the transfected cells are then cultured by conventional techniques to produce the molecules of the invention. In specific embodiments, the expression of the molecules of the invention is regulated by a constitutive, an inducible or a tissue, specific promoter. [003431 The host cells used to express the molecules identified by the methods of the invention may be either bacterial cells such as Escherichia coli~ or, preferably, eukaryotic cells, especially for the expression of whole recombinant immunoglobulin molecule. In particular, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for immunoglobulins (Foecking et as'., 1998, Gene 45:101; Cockett eta!., 1990, BiotTechnology 8:2). [00344] A variety of host-expression vector systems may be utilized to express the molecules identified by the methods of the invention. Such host-expression systems represent vehicles by which the coding sequences of the molecules of the invention may be produced and subsequently purified, but also represent cells which may, when transformed or transfected with the appropriate nucleotide coding sequences, express the molecules of the invention in situ. These include, but are not limited to, microorganisms such as bacteria (e.g., E. coll and B. sublilis) transformed with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA expression vectors containing coding sequences for the molecules .aueihads of the invention; yeast (e.g., Saccharomyces Pichia) transformed with recombinant yeast expression vectors containing sequences encoding the molecules identified by the methods of the invention; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing the sequences encoding the molecules identified by the methods of the invention; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus (CaMV) and tobacco mosaic virus (CMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing sequences encoding the molecules identified by the methods of the invention; or mammalian cell systems (e.g., COS, CHO, BHX, 293, 293T, 3T3 cells, lymphotic cells (see U.S. 5,807,715), Per C.6 cells (human retinal cells developed by Crucell) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K promoter). [00345] In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the molecule being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of pharmaceutical compositions of an antibody, vectors which direct the expression of high levels of fusion protein products that are readily purified may be desirable. Such vectors include, but are not limited, to the E. co!i expression vector pUR278 (Ruther et al., 1983, EMBOJ. 2:1791), in which the antibody coding sequence may be ligated individually into the vector in frame with the !ac Z coding region so that a fusion protein is produced; pIN vectors (Inouye & Inouye, 1985, Nucleic Acids Res. 13:3101-3109; Van Heeke & Schuster, 1989, J. Biol. Chem. 24:5503-5509); and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione 5-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption and binding to a matrix glutathione-agarose beads followed by elution in the presence of free gluta-thione. The pOEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety. [00346] In an insect system, Autographa cal~/'ornica nuclear polyhedrosis virus (AeNPY) is used as a vector to express foreign genes. The virus grows in Spodoptera frugiperda cells. The antibody coding sequence may be cloned individually into non¬essential regions (e.g.. the polyhedrin gene) of the virus and placed under control of an AeNPY promoter (e.g., the polyhedrin promoter). host cells, a number of viral-based expression systems may be utilized. In cases where an adenovirusis used as an expression vector, the antibody coding sequence of interest may be ligated to an adenovirus transcription/translation control complex, e.g., the late promoter and tripartite leader sequence. This chimeric gene may then be inserted in the adenovirus genome by in vitro or in vivo recombination. Insertion in a non-essential region of the viral genome (e.g., region El or E3) will result in a recombinant virus that is viable and capable of expressing the inimunoglobulin molecule in infected hosts (e.g., see Logan & Shenk, 1984, Proc. Nat!. Acadl Sd. USA 81:355-359). Specific initiation signals may also be required for efficient translation of inserted antibody coding sequences. These signals inclvde the ATO initiation codon and adjacent sequences. Furthermore, the initiation codon must be in phase with the reading frame of the desired coding sequence to ensi~ire translation of the entire insert. These exogenous translational control signals and initiation codons can be of a variety of origins, both natural and synthetic. The efficiency of expression maybe enhanced by the inclusion of appropriate transcription enhancer elements, transcription terminators, etc. (see Bittner et al., 1987, Methods in Enzymo!. 153:51-544). [00348] In addition, a host cell strain may be chosen which modulates the expression ~f the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or host systems can be chosen to ensure the correct modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. Such mammalian host cells include but are not limited to CHO, VERY, BHK, Hela, COS, MDCK, 293, 293T, 3T3, W138, BT483, HsS78T, H.TB2, BT2O and T47D, CRL7O3O and HsS78Bst. [00349] For long-term, high-yield production of recombinant proteins, stable expression is preferred. For example, cell lines which stably express an antibody of the invention may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, switched~~a a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines. This method may advantageously be used to engineer cell lines which express the antibodies of the invention. Such engineered cell lines may be particularly useful in screening and evaluation of compounds that interact directly or indirectly with the antibodies of the invention. (003501 A number of selection systems may be used, including but not limited to the herpes simplex virus thymidine kinase (Wigler et a!., 1977, Ce!! 11: 223), hypoxanthine¬guanine phosphoribosyltransferase (Szybalska & Szybalski, 1992, Proc. Nat!. Acad Sci. USA 48: 2Q2), and adenine phosphoribosyltransferase (Lowy eta!., 1980, Ce!! 22: 817) genes can be employed in tic-, hgprt- or aprt- cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler etal., 1980, Proc. Nat!. A cad. Sci. USA 77:357; O'Hare eta!., 1981, Proc. Nati. Acad Sci. USA 78: 1527); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, 1981, Proc. Nat!. Acad Sci. USA 78: 2072); neo, which confers resistance to the aminoglycoside G-418 C!inica! Pharmacy 12: 488-505; Wu and Wu, 1991, 3:87-95; Tolstoshev, 1993,Ann. Rev. Pharmaco!. Toxico!. 32:573-596; Mulligan, 1993, Science 260:926-932; and Morgan and Anderson, 1993, Ann. Rev. Biochem. 62:191-217; May, 1993, TIB TECH I l(5):155-215). Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et a!. (eds.), 1993, Current Protocols in Mo!ecu!ar Rio!ogy, John Wiley & Sons, NY; Kriegler, 1990, Gene Transfer and Expression. A Laboratory Manual Stockton Press, NY; and in Chapters 12 and 13, Dracopoli eta!. (eds), 1994, Current Protocols in Human Genetics. John Wiley & Sons, NY.; Colberre-Garapin eta!., 1981, J. Mo!. Bio!. 150:1; and hygro, which confers resistance to hygromycin (Santerre eta!., 1984, Gene 30:147). [00351] The expression levels of an antibody of the invention can be increased by vector amplification (for a review, see Bebbington and Hentschel, The use of vectors based on gene amulification for the exvression of cloned aenes in mammalian cells in DNA cloning. Vol.3 (Aeademic Press, New York, 1987). When a marker in the vector system expressing an antibody is ampliflable, increase in the level of inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the nucleotide sequence of the antibody, production of the antibody will also increase (Crouse eta!., 1983, Mo!. Ce!!. Bios'. 3:257). hestiell may be co-transfected with two expression vectors of the invention, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors may contain identical selectable markers which enable equal expression of heavy and light chain polypeptides. Alternatively, a single vector may be used which encodes both heavy and light chain polypeptides. In such situations, the light chain should be placed before the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, 1986, Nature 322:52; Kobler, 1980, Proc. Nat!. Acad Sci. USA 77:2197). The coding sequences for the heavy and light chains may comprise cDNA or genomic DNA. [00353] Once a molecule of the invention (i.e., antibodies) has been recombinantly expressed, it may be purified by any method known in the art for purification of polypeptides or antibodies, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubiity, or by any other standard technique for the purification of polypeptides or antibodies. 5.4 PROPHYLACTIC AND THERAPEUTIC METHODS [00354] The present invention encompasses administering one or more of the molecules of the invention (e.g., antibodies) to an animal, preferably a mammal, and most preferably a human, for preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADOC) mediated by FcyR is desired. The methods and compositions of the invention are particularly useful for the treatment or prevention of primary or metastatic neoplastic disease (i.e., cancer), and infectious diseases. Molecules of the invention may be provided in pharmaceutically acceptable compositions as known in the art or as described herein. As detailed below, the molecules of the inyention can be used in methods of treating or preventing cancer (particularly in passive immunotherapy), autoimmune disease, inflammatory disorders or infectious diseases . [00355] The molecules of the invention may also be advantageously utilized in combination with other therapeutic agents known in the art for the treatment or prevention of a cancer, autoimmune disease, inflammatory disorders or infectious diseases. In a specific embodiment, molecules of the invention may be used in combination with monoclonal or chimeric antibodies, lymphokines, or hematopoietic growth f~ctors (such as, e.g., IL-2, IL-3 and IL-7), which, for example, serve to increase the number or activity of with the molecules and, increase immune response. The molecules of the invention may also be advantageously utilized in combination with one or more drugs used to treat a disease, disorder, or infection such as, for example anti-cancer agents, anti-inflammatory agents or anti-viral agents, e.g., as detailed in sections 5.4.1.2 and 5.4.2.1 below. 5.4.1 CANCERS 1003561 The invention encompasses methods and composition for treatment or prevention of cancer or metastasis in a subject comprising administering to the subject a therapeutically effective amount of one or more molecules comprising a variant Fe region. (00357] Molecules of the invention (i.e., polypeptides, antibodies) comprising variant Fe regions can be used to prevent, inhibit or reduce the growth of primary tumors or metastasis of cancerous cells. In one embodiment, the molecule of the invention comprises a variant Fe that binds FcRIIIA and/or FcyRflA with a greater affinity than a comparable polypeptide comprising a wild type Fe region binds FcRIJIA and/or FcRILA, and/or said variant Fc region has an enhanced effector function, e.g., ADCC, CDC, phagocytosis, opsonization, etc. Such molecules can be used alone to treat or prevent cancer. In another embodiment, the molecule of the invention comprises a variant Fe region that binds FcRIIIA and/or FcRIIA with a greater affinity than a comparable polypeptide comprising a wild type Fe region binds FcRIIIA and/or FcRilA, and further binds FcRflB with a lower affinity than a comparable polypeptide comprising a wild-type Fc region binds FcRIIB, and/or said variant Fe region has an enhanced effector function, e.g., ADCC, CDC, phagocytosis, opsonization, etc. Such molecules can also be used alone to treat or prevent cancer. [003581 In some embodiments, the invention encompasses methods and compositions for the treatment or prevention of cancer in a subject with FcR polymorphisms such as those homozygous for the FRIIIA-158V or FcR1IIA-158F alleles. In some embodiments, the invention encompasses engineering therapeutic antibodies, e.g., tumor specific monoclonal antibodies in accordance with the methods of the invention such that the engineered antibodies have enhanced efficacy in patients homozygous for the low amnity allele of FcRifiA (158F). In other embodiments, the invention encompasses engineering therapeutic antibodies, e.g., tumor specific monoclonal antibodies in accordance with the methods of the invention such that the engineered antibodies have enhanced efficacy in patients homozygous for the high affinity allele of FcRflIA (158V). mbodiments, the engineered antibodies of the invention are particularly effective in treating and/or preventing non-Hodgldn's lymphoma (NHL). The engineered antibodies of the invention are therapeutically more effective than current therapeutic regimens for NHL, including but not limited to chemotherapy, and immunotherapy using anti-CD2O niAb, Rituximab. The efficacy of anti-CD2O monoclonal antibodies however depends on the FcR polymorphism of the subject (Carton et a!., 2002 Bs'oo~ 99: 754-8; Weng et at, 2003 JC!in Onco!.21(21):3940-7 both of which are incorporated hrein by reference in their entireties). These receptors are expressed on the surface of the effector cells and mediate ADCC. High affinity alleles, of the low affinity activating receptors, improve the effector cells' ability to mediate ADCC. The methods of the invention allow engineering anti-CD2O antibodies harboring Fe mutations to enhance their affinity to FcR on effector cells via their altered Fc domains. The engineered antibodies of the invention provide better immunotherapy reagents for patients regardiess of their EcyR polymorphism. [00360] An exemplary method for determining the efficacy of the engineered anti¬CD2O antibodies in a subject may include the following: Plasmids harboring chimeric anti¬HER2/neu heavy chain genes with Fe mutations that show substantially increased killing in ADCC can be be used as a backbone to transfer in the variable domain from the Rituximab heavy chain gene. The variable region from the anti-HER2/neu Fc variant is replaced with the variable region from Rituximab. Plasmids containing wild type Fe domains or a D265A mutation to abrogate FcR binding, or the anti-CD2O Fe variants are transiently cotransfected with the Rituximab light chain gene intq 293H cells, conditioned media and the antibody is purified over a protein G column using routine methods. [00361] Anti-CD20 mAbs harboring the Fc variants are tested by ADCC using a cultured B cell line to determine the ability of the Fe mutations to enhance ADCC. Standard ADCC is performed using methods disclosed herein. Lymphocytes are harvested from peripheral blood using a Ficoll-Paque gradient (Pharmacia). Target Daudi cells, a B-cell line expressing CD2O, are loaded with Europium (PerkinEimer) and incubated with effectors for 4 hrs at 370C. Released Europium is detected using a fluorescent plate reader (Wallac). The resulting ADCC data indicates the efficacy of the Fe variants to trigger NK cell mediated cytotoxicity and establish which anti -CD2O Fe variants can be tested with both patient samples and elutriated monocytes. Fe variants showing the greatest potential for enhancing the efficacy of the anti-CD2O antibody are then tested in an ADCC assay using PBMCs from patients. PBMC from healthy donors are used as effector cells. In vitro ADOC assays using anti-CD2O variants and Rituximab are performed in primary with follicular lymphoma. The specific FcR polymorphism of the donors is determined and cataloged using methods known in the art. ADCC assay is performed by effector cells from patients with different FcRIITA and FcyRIIA genotypes. [003621 According to an aspect of the invention, molecules (e.g., antibodies) of the invention comprising variant Fc regions enhance the efficacy of cancer immunotherapy by increasing the potency of the antibody effector function relative to a molecule containing the wild-type Fc region, e.g., ADCC, CDC, phagocytosis, opsonization, etc. In a specific embodiment, antibody dependent cellular toxicity and/or phagocytosis of tumor cells is enhanced using the molecules of the invention with variant Fe regions. Molecules of the invention may enhance the efficacy of immunotherapy cancer treatment by enhancing at least one antibody-mediated effector function. In one particular embodiment, a molecule of the invention comprising a variant Fe region enhances the efficacy of immunotherpay treatment by enhancing the complement dependent cascade. In another embodiment of the invention, the molecule of the invention comprising a variant Fe region enhances the efficacy of immunotherapy treatment by enhancing the phagocytosis and/or opsonization of the targeted tumor cells. In another embodiment of the invention, the molecule of the invention comprising a variant Fe region enhances the efficacy of treatment by enhancing antibody-dependent cell-mediated cytotoxicity ("ADCC") in destruction of the targeted tumor cells. [003631 The invention further contemplates engineering therapeutic antibodies (e.g., tumor specific monoclonal antibQdies) for enhancing the therapeutic efficacy of the therapeutic antibody, for example, by enhancing the effector function of the therapeutic antibody (e.g., ADCC). Preferably the therapeutic antibody is a cytotoxic and/or opsonizing antibody. It will be appreciated by one of skill in the art, that once molecules of the invention with desired binding properties (e.g., molecules with variant Fc regions with at least one amino acid modification, which modification enhances the affinity of the variant Fe region for FcRIIIA and/or FcRJIA relative to a comparable molecule, comprising a wild-type Fe region) have been identified (See Seefi~on 5.2 and Table 8) according to the methods of the invention, therapeutic antibodies may be engineered using standard recombinant DNA techniques and any known mutagenesis techniques, as described in Section 5.2.2 to produce engineered therapeutic carrying the identified mutation sites with the desired binding properties. Any of the therapeutic antibodies listed in Table 9 that have demonstrated therapeutic utility in cancer treatment, may be engineered according to the methods of the invention, for example, by modifying the Fe region to have an enhanced affinity for FcRflIA and/or FcRflA compared to a therapeutic antibody having a wild¬ the treatment and or prevention of a cancer characterized Wy a cancer antigen. Other therapeutic antibodies include those against pathogenic agents such as those against Streptococcus pneumoniae Serotype 6B, see, e.g., Sun et al., 1999, Infection and Immunity, 67(3): 1172-9. [00364] The Fc variants of the invention may be incorporated into therapeutic antibodies such as those disclosed herein or other Fc fusion clinical candidates, i.e., a molecule comprising an Fe regions which has been approved for us in clinical trials or any other molecule that may benefit from the Fe variants of the instant invention, humanized, affinity matured, modified or engineered versions thereof. [00365] The invention also encompasses engineering any other polypeptide comprising an Pc region which has therapeutic utility, including but not limited to ENBREL, according to the methods of the invention, in order to enhance the therapeutic efficacy of such polypeptides, for example, by enhancing the effector function of the polypeptide comprising an TABLE 9. THERAPEUTIC ANTIBODIES THAT CAN BE ENGINEERED ACCORDING TO THE METHODS OF THE INVENTION (Table Removed) [003661 Accordingly, the invention provides methods of preventing or treating cancer characterized by a cancer antigen, using a therapeutic antibody that binds a cancer antigen and is cytotoxic and has been modified at one or more sites in the Fc region, according to the invention, to bind Fc'yRIIIA and/or FcyRIIA with a higher affinity than the parent therapeutic antibody, and/or mediates effector function (e.g., ADOC, phagocytosis) more effectively. In another embodiment, the invention provides methods of preventing or treating cancer characterized by a cancer antigen, using a therapeutic antibody that binds a cancer antigen and is cytotoxic, and has been engineered according to the invention to bind FcRIIIA and/or FcRILA with a higher affinity and bind FcRIIB with a lower affinity than the parent therapeutic antibody, and/or mediates effector function (e.g., ADCC, phagocytosis) more effectively. The therapeutic antibodies that have been engineered are useful for prevention or treatment of cancer, since they have an enhanced cytotoxic activity (e.g., enhanced tumor cell killing and/or enhanced for example, ADCC activity or CDC activity). [00367] Cancers associated with a cancer antigen may be treated or prevented by administration of a therapeutic antibody that binds a cancer antigen and is cytotoxic, and has been engineered according to the methods of the invention to have, for example, an enhanced effector function. In one particular embodiment, the therapeutic antibodies engineered according to the methods of the invention enhance the antibody-mediated cytotoxic effect of the antibody directed at the particular cancer antigen. For example, but not by way of limitation, cancers associated with the following cancer antigens may be treated or prevented by the methods and compositions of the invention: KS 1/4 pan-carcinoma antigen (Perez and Walker, 1990, J. Immunol. 142:32-37; Bumal, 1988, Hybridoma 7(4):407-415), ovarian carcinoma antigen (CA125) (Yu eta!., 1991, Cancer Res. 51 (2):48-475), prostatic acid phosphate (Tailor et a!., 1990, Nuci. Acids Res. 1 8(l):4928), prostate specific antigen (Henttii and Vihko, 1989, Biochem. Biophys. Res. Comm. l0(2):903-9 10; Israeli et a!., 1993, Cancer Res. 53:227-230), melanoma-associated antigen p97 (Estin et at., 1989, J. Nat!. Cancer Instit. 81(6):445-44), melanoma antigen gp7S (Vijayasardahl et al., 1990,1 Exp. Med 171(4):1375-1380), high molecular weight melanoma antigen (HMW-MAA) (Natall eta!., 1987, Cancer 59:55-3; Mittelman et a!., 1990, J. Clin Invest. 86:2136-2144)), prostate specific membrane antigen, carcinoembryonic antigen (CEA) (Foon et a!., 1994, Proc. Am. Soc. Clin. Oncol. 13:294), polymorphic epithelial mucin antigen, human milk fat globule antigen, Colorectal tumor-associated antigens such as: CEA, TAG-72 (Yokata eta!., 1992, Cancer Res. 52:3402-3408), C017-lA (Ragnhammar et at., 1993, mt. J. Cancer 53:751-758); GICA 19-9 (Herlyn eta!., 1982, J. Clin. Immuno!. 2:135), CTA-1 and LEA, Burkitt's lymphoma antigen-38.13, CDl9 (Ghetie et a!., 1994, Blood 83:1329-1336), human B-lymphoma antigen-CD2O (Reffet a!., 1994, Blood 83:435-445), CD33 (Sgouros eta!., 1993, J. Nuci. Med 34:422-430), melanoma specific antigens such as ganglioside GD2 (Saleh eta!., 1993, J.Immunol., 151, 3390-3398), ganglioside GD3 (Shitara eta!., 1993, Cancer Immuno!. Immunother. 36:373-380), ganglioside GM2 (Livingston eta!., 1994, J. Clin. Onco!. 12:1036-1044), ganglioside GM3 (Hoon eta!., 1993, Cancer Res. 53:5244-5250), tumor-specific transplantation type of cell-surface antigen (TSTA) such as virally-induced tumor antigens including T-antigen DNA tumor viruses and envelope antigens of RNA tumor viruses, oncofetal antigen-alpha-fetoprotein such as CEA of colon, bladder tumor oncofetal antigen (Helistrom eta!., 1985, Cancer. Re:. 45:2210-21 88), differentiation antigen such as — 4~upiqg.o~pjnpni~ ~itigen L6, L20 (Hellatrom eta!., 1986, Cancer Res. 46:3917-3923), antigens of fibrosarcoma, human leukemia T cell antigen-Gp37 (Bhattacharya-Chatteijee et a!., 1988, J. of kninun. 141:1398-1403), neoglycoprotein, sphingolipids, breast cancer antigen such as EGFR (Epidermal growth factor receptor), HER2 antigen (j~l8S~IU), polymorphic epithelial mucin (PEM) (Hilkens et a!., 1992, Trends in Bio. Chem. Sci. 17:359), malignant human lymphocyte antigen-APO-l (Bernhard et al., 1989, Science 245:301-304), differentiation antigen (Feizi, 1985, Nature 3 14:53-57) such as I antigen found in fetal erthrocytes and primary endoderm, I(Ma) found in gastric adencarcinomas, M18 and M39 found in breast epithelium, SSEA-l found in myeloid cells, VEP8, VEP9, Myl, VIM-DS,and D156-22 found in colorectal cancer, TRA-1-85 (blood group H), Cl4~ found in colonic adenocarcinoma, F3 found in lung adenocarcinoma, AH6 found in gastiic cancer, Y hapten, Le~ found in embryonal carcinoma cells, TLS (blood group A), EGE receptor found in A43 1 cells , E1 series (blood group B) found in pancreatic cancer, FQlO.2 found in embryonal carcinoma cells, gastric adenocarcinoma, CO-S 14 (blood group Lea) found in adenocarcinoma, NS-l0 found in adenocarcinomas, CO-43 (blood group Leb), G49, EGE receptor, (blood group ALeb/LeY) found in colonic adenocarcinoma, 19.9 found in colon cancer, gastric cancer mucins, T5A7 found in myeloid cells, R24 found in melanoma, 4.2, GD3, Dl.l, OFA-1, G~, OFA-2, G1J2, Ml :22:25:8 found in embryonal carcinoma cells and SSEA-3, SSEA-4 found in 4-8-cell stage embryos. In another embodiment, the antigen is a T cell receptor derived peptide from a cutaneous T cell lymphoma (see Edelson, 1998, The Cancer Journa! 4:62). 1003681 Cancers and related disorders that can be treated or prevented by methods and compositions of the present invention include, but are not limited to, the following: Leukemias including, but not limited to, acute leukemia, aci.te lymphocytic leukemia, acute myelocytic leukemias such as myeloblastic, promyelocytic, myelomonocytic, monocytic, erythroleukemia leukemias and myelodysplastic syndrome, chronic leukemias such as but not limited to, chronic myelocytic (granulocytic) leukemia, chronic lymphocytic leuken~ia, hairy cell leukemia; polycythemia vera; lymphomas such as but not limited to Hodgkin'~s disease, non-Hodgidn's disease; multiple myelomas such as but not limited to smoldering multiple myeloma, nonsecretory myeloma, osteoselerotic myeloma, plasma cell leukemia, solitary plasmacytoma and extramedullary plasmacytoma, Waldenstr6m' s macroglobullnemia monoclonal gammopathy of undetermined significance; benign monoclonal gammopathy; heavy chain disease; bone and connective tissue sarcomas such as but not limited to bone sarcoma, osteosarcoma, chondrosarcoma, Ewing's sarcoma, malignant giant cell tumor, fibrosarcoma of bone, chordoma, periosteal sarcoma, soft-tissue fibrosarcoma, Kaposi's sarcoma, leiomyosarcoma, liposarcoma, lymphangiosarcoma, neurilenimoma, rhabdomyosarcoma, synovial sarcoma; brain tumors including but not limited to, glioma, astrocytoma, brain stem glioma, ependymoma, oligodendroglioma, nonglial tumor, acoustic neurinoma, craniopharyngioma, medulloblastoma, meningioma, pineocytoma, pineoblastoma, primary brain lymphoma; breast cancer including, but not limited to, adenocarcinoma, lobular (small cell) carcinoma, intraductal carcinoma, medullary breast cancer, mucinous breast cancer, tubular breast cancer, papillary breast cancer, Paget's disease, and inflammatory breast cancer; adrenal cancer, including but not limited to, pheochromocytom and adrenocortical carcinoma, thyroid cancer such as but not limited to papillary or follicular thyroid cancer, medullary thyroid cancer and anaplastic thyroid cancer; pancreatic cancer, including but not limited to, insulinoma, gastrmnoma, glucagonoma, vipoma,. somatostatin-secreting tumor, and carcinoid or islet cell tumor; pituitary cancers including but not limited to, Cushing's disease, prolactin-secreting tumor, acromegaly, and diabetes insipius; eye cancers including but not limited to, ocular melanoma such as iris melanoma, choroidal melanoma, and cilliary body melanoma, and retinoblastoma, vaginal cancers, including but not limited to, squamous cell carcinoma, adenocarcinoma, and melanoma; vulvar cancer, including but not limited to, squamous cell carcinoma, melanoma, adenocarcinoma, basal cell carcinoma, sarcoma, and Paget's disease; cervical cancers including but not limited to, squamous cell carcinoma, and adenocarcinoma; uterine cancers including but not limited to, endometrial carcinoma and uterine sarcoma; ovarian cancers including but not limited to, ovarian epithelial carcinoma, borderline tumor, germ cell tumor, and stromal tumor; esophageal cancers including but not limited to, squamous cancer, adenocarcinoma, adenoid cyctic carcinoma, mucoepidermoid carcinoma, adenosquamous carcinoma, sarcoma, melanoma, plasmacytoma, verrucous carcinoma, and ~at cell (small cell) carcinoma, stomach cancers including but not limited to, adenocarcinoma, fungating (polypoid), ulcerating, superficial spreading, diffusely spreading, malignant lymphoma, liposarcoma, fibrosarcoma, and carcinosarcoma; colon cancers; rectal cancers; liver cancers including but not limited to hepatocellular carcinoma and hepatoblastoma, gallbladder cancers including but not limited to, adenocarcinoma, cholangiocarcinomas including but not limited to, pappillary, nodular, and diffuse; lung cancers including but not limited to, non-small cell lung cancer, squamous cell carcinoma (epidermoid carcinoma), adenocarcinoma, large-cell carcinoma and small-cell lung cancer, testicular cancers including but not limited to, germinal tumor, seminoma, anaplastic, classic (typical), spermatocytic, nonseminoma, embryonal carcinoma, teratoma carcinoma, choriocarcinoma (yolk-sac tumor), prostate cancers including but not limited to, psarcoma, and rhabdomyosarcoma; penal cancers; oral cancers including but not limited to, squamous cell carcinoma; basal cancers; salivary gland cancers including but not limited to, adenocarcinoma, mucoepidermoid carcinoma, and adenoidcystic carcinoma; pharynx cancers including but not limited to, squamous cell cancer, and verrucous; skin cancers including but not limited to, basal cell carcinoma, squamous cell carcinoma and melanoma, superficial spreading melanoma, nodular melanoma, lentigo malignant melanoma, acral lentiginous melanoma; kidney cancers including but not limited to, renal cell cancer, adenocarcinoma, hypernephroma, fibrosarcoma, transitional cell cancer (renal pelvis andl or uterer); Wilms' tumor; bladder cancers including but not limited to, transitional cell carcinoma, squamous cell cancer, adenocarcinoma, carcinosarcoma. In addition, cancers include myxosarcoma, osteogenic sarcoma, endotheliosarcoma, lymphangloendotheliosarcoma, mesothelioma, synovioma, hemangioblastoma, epithelial carcinoma, cystadenocarcinoma, bronchogenic carcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma and papillary adenocarcinomas (for a review of such disorders, see Fishman et a!., 1985, Medicine, 2d Ed., J.B. Lippincott Co., Philadelphia and Murphy eta!., 1997, Informed L)ecisions: The Complete Book of Cancer Diap,nosis, Treatment, and Recovery, Viking Penguin, Penguin Books U.S.A., Inc., United States of America). [003691 Accordingly, the methods and compositions of the invention are also useful in the treatment or prevention of a variety of cancers ~r other abnormal proliferative diseases, including (but not limited to) the following: carcinoma, including that of the bladder, breast, colon, kidney, liver, lung, ovary, pancreas, stomach, prostate, cervix, thyroid and skin; including squamous cell carcinoma; hematopoictic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, B-cell lymphoma, T-cell lymphoma, Burketts lymphoma; hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias and promyelocytic leukemia; tumors of mesenchymal origin, including fibrosarcoma and rhabdomyoscarcoma; other tumors, including melanoma, seminoma, tetratocarcinoma, neuroblastoma and glioma; tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma, and schwannomas; tumors of mesenchymal origin, including fibrosafeoma,, rhabdomyoscarama, and osteosarcoma; and other tumors, including melanoma, xenoderma pegmentosum, keratoactanthoma, seminoma, thyroid follicular cancer and teratocarcinoma. It is also contemplated that cancers caused by aberrations in apoptosis would also be treated by the methods and compositions of the invention. Such cancers may include but not be limited to follicular lymphomas, carcinomas with p53 mutations, hormone dependent and ovary, and precancerous lesions such as tanultal adenomatous polyposis, and myelodysplastic syndromes. In specific embodiments, malignancy or dysproliferative changes (such as metaplasias and dysplasias), or hyperproliferative disorders, are treated or prevented by the methods and compositions of the invention in the ovary, bladder, breast, colon, lung, skin, pancreas, or uterus. In other specific embodiments, sarcoma, melanoma, or leukemia is treated or prevented by the methods and compositions of the invention. (003701 In a specific embodiment, a molecule of the invention (e.g., an antibody comprising a variant Fc region, or a therapeutic monoclonal antibody engineered according to the methods of the invention) inhibits or reduces the growth of primary tumor or metastasis of cancerous cells by at least 99%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 60%, at least 50%, at least 45%, at least 40%, at least 45%, at least 35%, at least 30%, at least 25%, at least 20%, or at least 10% relative to the growth of primary tumor or metastasis in the absence of said molecule of the invention. 5.4.1.1 COMBINATION THERAPY [003711 The invention further encompasses administering the molecules of the invention in combination with other therapies known to those skilled in the art for the treatment or prevention of cancer, including but not limited to, current standard and experimental chemotherapies, hormonal therapies, biological therapies, inimunotherapies, radiation therapies, or surgery. In some embodiments, the molecules of the invention may be administered in combination with a therapeutically or prophylactically effective amount of one or more anti-cancer agents, therapeutic antibodies (e.g., antibodies listed in Table 9), or other agents known to those slcilled in the art for the treatment and/or prevention of cancer (See Section 5.4.1.2). [003721 In certain embodiments, one or more molecule of the invention is administered to a mammal, preferably a human, concurrently with one or more other therapeutic agents useful for the treatment of cancer. The term "concurrently" is not limited to the administration of prophylactic or therapeutic agents at exactly the same time, but rather it is meant that a molecule of the invention and the other agent are administered to a mammal in a sequence and within a time interval such that the molecule of the invention can act together with the other agent to provide an increased benefit than if they were administered otherwise. For example, each prophylactic or therapeutic agent (e.g., chemotherapy, radiation therapy, hormonal therapy or biological therapy) may be time or sequentially in any order at different points in time; however, if not administered at the same time, they should be administered sufliciently close in time so as to provide the desired therapeutic or prophylactic effect. Each therapeutic agent can be administered separately, in any appropriate form and by any suitable route. In various embodiments, the prophylactic or therapeutic agents are administered less than 1 hour apart, at about 1 hour apart, at about 1 hour to about 2 hours apart, at about 2 hours to about 3 hours apart, at about 3 hours to about 4 hours apart, at about 4 hours to about 5 hours apart, at about 5 hours to about 6 hours apart, at about 6 hours to about 7 hours apart, at about 7 hours to about 8 hours apart, at about 8 hours to about 9 hours apart, at about 9 hours to about 10 hours apart, at about 1 Q hours to about 11 hours apart, at about 11 hours to about 12 hours apart, no more than 24 hours apart or no more than 48 hours apart. In preferred embodiments, two or more components are administered within the same patient visit. [003731 In other embodiments, the prophylactic or therapeutic agents are administered at about 2 to 4 days apart, at about 4 to 6 days apart, at about 1 week part, at about 1 to 2 weeks apart, or more than 2 weeks apart. In preferred embodiments, the prophylactic or therapeutic agents are administered in a time frame where both agents are still active. One skilled in the art would be able to determine such a time frame by determining the half life of the administered agents. [00374] In certain embodiments, the prophylactic or therapeutic agents of the invention are cyclically administered to a subject. Cycling therapy involves the administration of a first agent for a period of time, followed by the administration of a second agent and/or third agent for a period of time and repeating this sequential administration. Cycling therapy can reduce the development of resistance to one or more of the therapies, avoid or reduce the side effects of one of the therapies, and/or improves the efficacy of the treatment [003751 In certain embodiments, prophylactic or therapeutic agents are administered in a cycle of less than about 3 weeks, about once every two weeks, about once every 10 days or about once every week. One cycle can comprise the administration of a therapeutic or prophylactic agent by infusion over about 90 minutes every cycle, about 1 hour every cycle, about 45 minutes every cycle. Each cycle can comprise at least 1 week of rest, at least 2 weeks of rest, at least 3 weeks of rest. The number of cycles administered is from about I to about 12 cycles, more typically from about 2 to about 10 cycles, and more typically from about 2 to about 8 cycles. embodiments, the therapeutic and prophylactic agents of the invention are administered in metronomic dosing regimens, either by continuous infusion or frequent administration without extended rest periods. Such metronomic administration can involve dosing at constant intervals without rest periods. Typically the therapeutic agents, in particular cytotoxic agents, are used at lower doses. Such dosing regimens encompass the chronic daily administration of relatively low doses for extended periods of time. In preferred embodiments, the use of lower doses can minimize toxic side effects and eliminate rest periods. In certain embodiments, the therapeutic and prophylactic agents are delivered by chronic low-dose or continuous infusion ranging from about 24 hours to about 2 days, to about 1 week, to about 2 weeks, to about 3 weeks to about 1 month to about 2 months, to about 3 months, to about 4 months, to about 5 months, to about 6 months. The scheduling of such dose regimens can be optimized by the skilled oncologist. [003771 In other embodiments, courses of treatment are administered concurrently to a manunal, i.e., individual doses of the therapeutics are administered separately yet within a time interval such that molecules of the invention can work together with the other agent or agents. For example, one component may be administered one time per week in combination with the other components that may be administered one time every two weeks or one time every three weeks. In other words, the dosing regimens for the therapeutics are carried out concurrently even if the therapeutics are not administered simultaneously or within the same patient visit. [00378] When used in combination with other prophylactic and/or therapeutic agents, the molecules of the invention and the prophylactic and/or therapeutic agent can act additively or, more preferably, synergistically. In one embodiment, a molecule of the invention is administered concurrently with one or more therapeutic agents in the same pharmaceutical composition. In another embodiment, a molecule of the invention is administered concurrently with one or more other therapeutic agents in separate pharmaceutical compositions. In still another embodiment, a molecule of the invention is administered prior to or subsequent to administration of another prophylactic or therapeutic agent. The invention contemplates administration of a molecule of the invention in combination with other prophylactic or therapeutic agents by the same or different routes of administration, e.g., oral and parenteral. In certain embodiments, when a molecule of the invention is administered concurrently with another prophylactic or therapeutic agent that potentially produces adverse side effects including, but not limited to, toxicity, the prophylactic or therapeutic agent can advantageously be administered at a dose that fails below the threshold that the adverse side effect is elicited. saIe amounts and frequencies of administration provided herein are encompassed by the terms therapeutically effective and prophylactically effective. The dosage and frequency further will typically vary according to factors specific for each patient depending on the specific therapeutic or prophylactic agents administered, the severity and type of cancer, the route of administration, as well as age, body weight, response, and the past medical history of the patient. Suitable regimens can be selected by one skilled in the art by considering such factors and by following, for example, dosages reported in the literature and recommended in the Physician's Desk Reference (56"' ed., 2002). 5.4.1.2 OTHER TH~RAPEUTIC/PROPHYLACflC AGENTS (003801 In a specific embodiment, the methods of the invention encompass the administration of one or more molecules of the invention with one or more therapeutic agents used for the treatment and/or prevention of cancer. In one embodiment, angiogenesis inhibitors may be administered in combination with the molecules of the invention. Angiogenesis inhibitors that can be used in the methods and compositions of the invention include but are not limited to: Angiostatin (plasminogen fragment); antiangiogenic antithrombin III; Angiozyme; ABT-627; Bay 12-9566; Benefin; Bevacizumab; BMS¬275291; cartilage-derived inhibitor (CDI); CM; CD59 complement fragment; CEP-7055; Col 3; Combretastatin A-4; Endostatin (collagen XVIII fragment); Fibronectin fragment; (Jro-beta; Halofuginone; Heparinases; Heparin hexasaceharide fragment; HIv1V833; Human chorionic gonadotropin (hCG); IM-862; Interferon alpha/beta/gamma; Interferon inducible protein (IP-lO); Interleukin-12; Kringle 5 (plasminogen fragment); Marimastat, Metalloproteinase inhibitors (TIMPs); 2-Methoxyestradiol; MlvII 270 (CGS 27023A); MoAb IMC-l Cli; Neovastat; NM-3; Panzem; P1-8 8; Placental ribonuclease inhibitor; Plasminogen activator inhibitor; Platelet factor-4 (PF4); Prinomastat Prolactin l6kD fragment; Proliferin-related protein (PRP); PTK 787/ZK 222594; Retinoids; Solimastat Squalamine; SS 3304; SU 5416; SU6668; SUl 1248; Tetrahydrocortisol-S; tetrathiomolybdate; thalidomide; Thrombospondin-l (TSP-i); TNP-470; Transforming growth factor-beta (TGF-b); Vasculostatin; Vasostatin (caireticulin fragment); ZD6 126; ZD 6474; farnesyl transferase inhibitors (FTI); and bisphosphonates. [003811 Anti-cancer agents that can be used in combination with the molecules of the invention in the various embodiments of the invention, including pharmaceutical compositions and dosage forms and kits of the invention, include, but are not limited to: acivicin; aclarubicin; acodazole hydrochioride; acronine; adozelesin; aldesleukin aminjametantrone acetate; aminoglutethimide; amsacrine; anastrozole; antbramycin; asparaginase; asperlin; azacitidine; azetepa; azotomycin; batimastat; beuzodepa; bicalutamide; bisantrene hydrochloride; bisnafide dimesylate; bizelesin; bleomycin sulfate; brequinar sodium; bropirimine; busulfan; cactinomycin; calusterone; caracemide; carbetimer; carboplatin; carmustine; carubicin hydrochloride; carzelesin; cedefingol; chiorambudil; cirolemycin; cisplatin; cladribine; crisnatol mesylate; cyclophosphamide; cytarabine; dacarbazine; dactinomycin; daunorubicin hydrochloride; decitabine; dexormaplatin; dezaguanine; dezaguanine mesylate; diaziquone; docetaxel; doxorubicin; doxorubicin hydrochloride; droloxifene; droloxifene citrate; dromostanolone propionate; duazomycin; edatrexate; eflornithine hydrochloride; elsamitrucin; enloplatin; enpromate; epipropidine; epirubicin hydrochloride; erbulozole; esorubicin hydrochloride; estramustine; estramustine phosphate sodium; etanidazole; etoposide; etoposide phosphate; etoprine; fadrozole hydrochloride; fazarabine; fenretinide; floxuridine; fludarabine phosphate; fluorouracil; fiurocitabine; fosquidone; fostriecin sodium; gemcitabine; gemcitabine hydrochloride; hydroxyurea; idarubicin hydrochloride; ifosfamide; ilmofosine; interleukin II (including recombinant interleukin II, or r1t2), interferon alfa-2a, interferon alfa-2b; interferon alfa-nl ; interferon alfa-n3; interferon beta-I a; interferon gamma-I b; iproplatin; irinotecan hydrochloride; lanreotide acetate; letrozole; leuprolide acetate; liarozole hydrochloride; lometrexol sodium; lomustine; losoxantrone hydrochloride; masoprocol; maytansine; mechlorethamine hydrochloride; megestrol acetate; melengestrol acetate; melphalan; menogaril; mercaptopurmne; methotrexate; methotrexate sodium; metoprine; meturedepa, mitindomide; mitocarcin; mitocromin; mitogillin; mitomalcin mitomycin; mitosper; mitotane; mitoxantrone hydrochloride; mycophenolic acid; nocodazole; nogalamycin; ormaplatin; oxisuran; paclitaxel; pegaspargase; peliomycin; pentamustine; peplomycin sulfate; perfosfbmide; pipobroman; piposulfan; piroxantrone hydrochloride; plicamycin; plomestane; porfimer sodium; porfiromycin; prednimustine; procarbazine hydrochloride; puromycin; puromycin hydrochloride; pyrazofurin riboprine; rogietimide; safingol; safingol hydrochloride; semustine; simtrazene; sparfosate sodium; sparsomycin; spirogermanium hydrochloride; spiromustine; spiroplatin; streptonigrmn; streptozocin; sulofenur; talisomycin tecogalan sodium; tegafur; teloxantrone hydrochloride; temoporfin; teniposide; teroxirone; testolactone; thiamiprine; thioguanine; thiotepa; tiazofurin tirapazamine; toremifene citrate; trestolone acetate; triciribine phosphate; trimetrexate; trimetrexale glucuronate; triptorelin; tubulozole hydrochloride; uracil mustard; uredepa, vapreotide; verteporfin; vinblastine sulfate; vincristine sulfate; vindesine; vindesine sulfate; vinepidine sulfate; vinglycinate sulfate; vinleurosine sulfate; vinorelbine vinzolidine sulfate; vorozole; zeniplatin; zinostatin; zorubicin hydrochloride. Other anti-cancer drugs include, but are not limited to: 20-epi-l ,25 dihydroxyvitainin D3; 5-ethynyluracil; abiraterone; aclarubicin; acylfulvene; adecypenol; adozelesin; aldesleukin; ALL-TK antagonists; altretamine; ambamustine; amidox; amifostine; axninolevulinic acid; amrubicin; amsacrine; anagrelide; anastrozole; andrographolide; angiogenesis inhibitors; antagonist D; antagonist 0; antarelix; anti-dorsalizing morphogenetic protein-I; antiandrogen, prostatic carcinoma; antiestrogen; antineoplaston; antisense oligonucleotides; aphidicolin glycinate; apoptosis gene modulators; apoptosis regulators; apurinic acid; ara-CDP-DL-PTBA; arginine deanxinase; asulacrine; atamestane; atrimustine; axinastatin 1; axinastatin 2; axinastatin 3; azasetron; azatoxin; azatyrosine; baccatin Ill derivatives; balanol; badmastat BCRIABL antagonists; benzochlorins; benzoylstaurosporine; beta lactam derivatives; beta-alethine; betaclamycin B; betulinic acid; bFGF inhibitor, bicalutamide; bisantrene; bisaziridinylspermine; bisnafide; bistratene A; bizelesin; breflate; bropirimine; budotitane; buthionine sulfoximine; calcipotriol; caiphostin C; camptothecin derivatives; canarypox IL-2; capecitabine; carboxamide-amino-triazole; carboxyamidotriazole; CaRest M3; CARN 790; cartilage derived inhibitor; carzelesin; casein kinase inhibitors (ICOS); castanospermine; cecropin B; cetrorelix; chlorins; chloroquinoxaline sulfonamide; cicaprost; cis-porphyrin; cladribine; clomifene analogues; clotrimazole; collismycin A; collismycin B; combretastatin A4; combretastatin analogue; conagenin; crambescidin 8l~; crisnatol; cryptophycin 8; cryptophycin A derivatives; curacin A; cyclopentanthraquinones; cycloplatam; cypemycin; cytarabine ocfosfate; cytolytic factor; cytostatin; dadiximab; decitabine; dehydrodidemnin B; deslorelin; dexamethasone; dexifosfamide; dexrazoxane; dexverapamil; diaziquone; didemnin B; didox; diethylnorspermine; dihydro-5-azacytidine; dihydrotaxol, 9-; dioxamycin; diphenyl spiromustine; docetaxel; docosanol; dolasetron; doxifluridine; droloxifene; dronabinol; duocarmycin SA; ebselen ecomustine; edelfosine; edrecolomab; eflornithine; elemene; emitefur; epirubicin; epristeride; estramustine analogue; estrogen agonists; estrogen antagonists; etanidazole; etoposide phosphate; exemestane; fadrozole; fazarabine; fenretinide; fllgrastim; finasteride; flavopiridol; flezelastine; fluasterone; fludarabine; fluorodaunorunicin hydrochloride; forfenimex; formestane; fostriecin; fotemustine; gadolinium texaphyrin, gallium nitrate; galocitabine; ganirelix; gelatinase inhibitors; gemcitabine; glutathione inhibitors; hepsulfam; heregulin; hexamethylene bisacetamide; hypericin; ibandronic acid,~ idarubicin; idoxifene; idramantone; ilmofosine; iomastat; imidazoacridones; imiquimod; immunostimulant peptides; insulin-like growth factor-i receptor inhibitor; interf~ron agonists; interferons; interleukins; lobenguane; 4-; iroplact irsogladine; isobengazole; isohomohalicondrin B; itasetron; jasplakinolide; kahalalide F; lamellarin-N triacetate; lanreotide; leinamycin; lenograstim; lentinan sulfate; leptolstatin; letrozole; leukemia inhibiting factor; leukocyte alpha interferon; leuprolide+estrogen+progesterone; leuprorelin; levamisole; liarozole; linear polyamine analogue; lipophilic disaccharide peptide; lipophilic platinum compounds; lissoclinamide 7; lobaplatin; lombricine; lometrexol; lonidamine; losoxantrone; lovastatin; loxoribine; lurtotecan; lutetium texaphyrin; lysofylline; lytic peptides; maitansine; mannostatin A; marimastat masoprocol; maspin; matrilysin inhibitors; matrix metalloproteinase inhibitors; menogaril; merbarone; meterelin; methioninase; metoclopramide; MIF inhibitor; mifepristone; miltefosine; mirimostim mismatched double stranded RNA; mitoguazone; mitolactol; mitomycin analogues; mitonafide; mitotoxin fibroblast growth factor-saporin; mitoxantrone; mofarotene; molgramostim; monoclonal antibody, human chorionic gonadotrophin; monophosphoryl lipid A+myobacterium cell wall sk; mopidamol; multiple drug resistance gene inhibitor; multiple tumor suppressor 1-based therapy; mustard anticancer agent; mycaperoxide B; mycobacterial cell wall extract, myriaporone; N-acetyldinaline; N-substituted benzamides; nafarelin; nagrestip; naloxone+pentazocine; napavin; naphterpin; nartograstim; nedaplatin; nemorubicin; neridronic acid; neutral endopeptidase; nilutamide; nisamycin; nitric oxide modulators; nitroxide antioxidant; nitrullyn; 06-benzylguanine; octreotide; okicenone; oligonucleotides; onapristone; ondansetron; ondansetron; oracin; oral cytokine inducer; ormaplatin; osaterone; oxaliplatin; oxaunomycin; paclitaxel; paclitaxel analogues; paclitaxel derivatives; palauamine; palmitoylrhizoxin; pamidronic acid; panaxytriol; panomifene; parabactin; pazelliptine; pegaspargase; peldesine; pentosan polysulfate sodium; pentostatin; pentrozole; perfiubron; perfosfamide; perillyl alcohol; phenazinomycin; phenylacetate; phosphatase inhibitors; picibanil; pilocarpine hydrochloride; pirarubicin; piritrexim; placetin A; placetin B; plasminogen activator inhibitor; platinum complex; platinum compounds; platinum-triamine complex; porfimer sodium; por.firomycin; prednisone; propyl bis-acridone; prostaglandin J2; proteasome inhibitors; protein A-based immune modulator, protein kinase C inhibitor, protein kinase C inhibitors, microalgal; protein tyrosine phosphatase inhibitors; purine nucleoside phosphorylase inhibitors; purpurins; pyrazoloacridine; pyridoxylated hemoglobin polyoxyethylene conjugate; raf antagonists; raltitrexed; ramosetron; ras farnesyl protein transferase inhibitors; ras inhibitors; ras-GAP inhibitor, retelliptine demethylated; rhenium Re 186 etidronate; rhizoxin ribozymes; Ril retinamide; rogletimide; rohitukine; romurtide; roquinimex; rubiginone Bl; ruboxyl; safingol; saintopin; SarCNU; sarcophytol A; sargramostim; Sdi 1 mimetics; semustine; sense oligonucleotides; signal transducfi6iilnhibitors; signal transduction modulators; single chain antigen binding protein; sizofiran; sobuzoxane; sodium borocaptate; sodium phenylacetate; solverol; somatomedin binding protein; sonermin; sparfosic acid; spicamycin D; spiromustine; splenopentin; spongistatin 1; squalamine; stem cell inhibitor; stem-cell division inhibitors; stipiamide; stromelysin inhibitors; sulfinosine; superactive vasoactive intestinal peptide antagonist; suradista; suramin; swainsonine; synthetic glycosaminoglycans; tallimustine; tamoxifen methiodide; tauromustine; tazarotene; tecogalan sodium; tegaflir; tellurapyrylium; telomerase inhibitors; temoporfin; temozolomide; teniposide; tetrachlorodecaoxide; tetrazomine; thaliblastine; thiocoraline; tbrombopoietin; thrombopoietin mimetic; thymalfasin; thymopoietin receptor agonist; thymotrinan; thyroid stimulating hormone; tin ethyl etiopurpurin; tirapazamine; titanocene bichloride; topsentin; toremifene; totipotent stem cell factor; translation inhibitors; tretinoin; triacetyluridine; triciribine; trimetrexate; triptorelin tropisetron; turosteride; tyrosine kinase inhibitors; tyrphostins; UBC inhibitors; ubenimex; urogenital sinus-derived growth inhibitory factor; urokinase receptor antagonists; vapreotide; variolin B; vector system, eryibrocyte gene therapy; velaresol; veramine; verdins; verteporfin; vinorelbine; vinxaltine; vitaxin; vorozole; zanoterone; zeniplatin; zilascorb; and zinostatin stimalamer. Preferred additional anti-cancer drugs are 5-fluorouradil and leucovorin. [00382] Examples of therapeutic antibodies that can be used in methods of the invention include but are not limited to ZENAPAX(E) (daclizumab) (Roche Pharmaceuticals, Switzerland) which is an immunosuppressive, humanized anti-CD2S monoclonal antibody for the prevention of acute renal allograft rejection; PANOREX~ which is a murine anti-17-IA cell surface antigen IgG2a antibody (Glaxo Wellcome/Centocor); BEC2 which is a murine anti-idiotype (GD3 epitope) IgG antibody (ImClone System); IMC-C225 which is a chimeric anti-EGFR IgG antibody (ImOlone System); VITAX1N~' which is a humanized anti-aVI33 integrin antibody (Applied Molecular Evolution/MedImmune); Smart M195 which is a humanized anti-CD33 IgG antibody (Protein Design Lab/Kanebo); LYMPHOCIDF?~ which is a humanized anti-CD22 IgG antibody (Immunomedics); ICM3 is a humanized anti-ICAM3 antibody (ICOS Pharm); lDEC-l 14 is a primatied anti-CD8O antibody (IDEC Pbarm/Mitsubishi); IDEC-13 1 is a humanized anti-CD4OL antibody. (IDEC/Eisai); IDEC-1 51 is a primatized anti-CD4 antibody (IDEC); IDEC-152 is a primatized anti-CD23 antibody (IDEC/Seikagaku); SMART anti-CD3 is a humanized anti¬CD3 IgO (Protein Design Lab); 501.1 is a humanized anti-complement factor 5 (CS) antibody (Alexion Pharm); D2E7 is a humanized anti-ThF-a antibody (CATIBASF); CDP87O is a humanized anti-TNF-a Fab fragment (Celltech); IDEC-15 1 is a primatized (IDEC Pharm/SmithKline Beecham); MDX t)4isahuman anti¬CD4 IgG antibody (Medarex/Eisai/Genmab); CDP57l is a humanized anti-TNF-a IgG4 antibody (Celitech); LDP-02 is a humanized anti-a4137 antibody (LeukoSite/Genentech); OrthoClone OKT4A is a humanized anti-CD4 IgG antibody (Ortho Biotech); ANTO VATh is a humanized anti-CD4OL IgO antibody (Biogen); ANTEGRENThI is a humanized anti¬VLA-4 IgG antibody (Elan); and CAT-152 is a human anti-TGF-f3~ antibody (Cambridge Ab Tech). Other examples of therapeutic antibodies that can be used in accordance with the invention are presented in Table 9. 5.4.2 AUTOIMMUNE DISEASE AND INFLAMMATORY DISEASES [003831 In some embodiments, molecules Qf the invention comprise a variant Fe region, having one or more amino acid modifications in one or more regions, which modification increases the affinity of the variant Fc region for FcyRIIB but decreases the affinity of the variant Fc region for FcRHIA and/or FcRIIA. Molecules of the invention with such binding characteristics are useful in regulating the immune response, e.g., m inhibiting the immune response in connection with autoimmune diseases or inflammatory diseases. Although not intending to be bound by any mechanism of action, molecules of the invention with an enhanced affinity for FcRIIB and a decreased affinity for Fc'RIIIA and/or FcRIIA may lead to dampening of the activating response to FcR and inhibition of cellular responsiveness. [00384] In some embodiments, a molecule of the invention comprising a variant Fc region is not an immunoglobulin, and comprises at least one amino acid modification which modification increases the affinity of the variant Fc region for FcRTIB relative to a molecule comprising a wild-type Fc region. In other embodiments, said molecule further comprises one or more amino acid modifications, which modifications decreases the affinity of the molecule for an activating FoyR. In some embodiments, the molecule is a soluble (L e., not membrane bound) Fc region. The invention contemplates other amino acid modifications within the soluble Fe region which modulate its affinity for various Fe receptors, including those known to one skilled in the art as described herein. In other embodiments, the molecule (e.g., the Fe region comprising at least one or more amino acid modification) is modified using techniques known to one skilled in the art and as described herein to increase the in vivo half life of the Fe region. Such molecules have therapeutic utility in treating and/or preventing an autoimmune disorder. Although not intending to be bound by any mechanism of actions, such molecules with enhanced affinity for FcRUB will lead to a dampening of the activating receptors and thus a dampening of the immune Slwa~utic efficacy for treating and/or preventing an autoimmune disorder. [003851 In certain embodiments, the one or more amino acid modifications, which increase the affinity of the variant Fe region for FcyRIIB but decrease the affinity of the variant Fe region for FcyRIIIA comprise a substitution at position 246 with threonine and at position 396 with histidine; or a substitution at position 268 with aspartic acid and at position 318 with aspartic acid; or a substitution at position 217 with seine, at position 378 with valine, and at position 408 with arginine; or a substitution at position 375 with cysteine and at position 39~ with leucine; ~r a substitution at position 246 with isolcucine and at position 334 with asparagine. In one embQdiment, the one or more amino acid modifications, which increase the affinity of the vaiiant Fe region for FcyRIIB but decrease the affinity of the variant Fe region for FcRJIIA comprise a substitution at position 247 with leucine. In another embodiment, the one or more amino acid modification, which increases the affinity of the variant Fe region for Fc-yRIIB but decreases the affinity of the variant Fc region for FcRIIIA comprise a substitution at position 372 with tyrosine. In yet another embodiment, the one or more amino acid modification, which increases the affinity of the variant Fe region for FcRUB but decreases the affinity of the variant Fe region for FcRIIIA comprise a substitution at position 326 with glutamic acid. In one embodiment, the one or more amino acid modification, which increases the affinity of the variant Fe region for FcRIIB but decreases the affinity of the variant Fe region for FcRIIIA comprise a substitution at position 224 with leucme. [00386] The variant Fe regions that have an enhanced affinity for FcRIIB and a decreased affinity for FcRIIIA and/or FcRITA relative to a comparable molecule comprising a wild-type Fe region, may be used t~ treat or prevent autoimmune diseases or inflammatory diseases. The present invention provides methods of preventing, treating, or managing one or more symptoms associated with an autoimmune or inflammatory disorder in a subject, comprising administering to said subject a therapeutically or prophylactically effective amount of one or more molecules of the invention with variant Fe regions that have an enhanced affinity for FcR.UB and a decreased affinity for FcRIIIA and or FcRIIA relative to a comparable molecule comprising a wild type Fe region. [003871 The invention also provides methods for preventing, treating, or managing one or more symptoms associated with an inflammatory disorder in a subject further comprising, administering to saW subject a therapeutically or prophylactically effective amount of one or more anti-inflammatory agents. The invention also provides methods for preventing, treating, or managing one or more symptoms associated with an autoimmune administering to said subject a therapeutically or prophylactically effective amount of one or more immunomodulatory agents. Section 5.4.2.1 provides non-limiting examples of anti-inflammatory agents and immunomodulatory agents. [003881 Examples of autoimmune disorders that may be treated by administering the molecules of the present invention include, but are not limited to, alopecia areata, ankylosing spondylitis, antiphospholipid syndrome, autoimmune Addison's disease, autoimmune diseases of the adrenal gland, autoimmune hemolytic anemia, autoimmune hepatitis, autoinirnune oophoritis and orchitis, autoimmune thrombocytopenia, Behcet's disease, bullous pemphigoid, cardiomyopathy, ~eliac sprue-dermatitis, chronic fatigue immune dysfunction syndrome (OFIDS), chronic inflammatory demyelinating polyneuropathy, Churg-Strauss syndrome, cicatrical pemphigoid, CREST syndrome, cold agglutinin disease, Crohn's disease, discoid lupus, essential mixed cryoglobulinemia, fibromyalgia-fibromyositis, glomerulonephritis, Graves' disease, Guillain-Barre, Ilashimoto's thyroiditis, idiopathic pulmonary fibrosis, idiopathic thrombocytopenia purpura (ITP), IgA neuropathy, juvenile arthritis, lichen planus, lupus erthematosus, M6ni~re's disease, mixed connective tissue disease, multiple sclerosis, type 1 or immune-mediated diabetes mellitus, myasthenia gravis, pemphigus vulgaris, pernicious anemia, polyarteritis nodosa, polychrondritis, polyglandular syndromes, polymyalgia rheumatica, polymyositis and dermatomyositis, primary aganunaglobulinemia, primary biliary cirrhosis, psoriasis, psoriatic arthritis, Raynauld's phenomenon, Reiter's syndrome. Rheumatoid arthritis, sarcoidosis, seleroderma, Sj~gren's syndrome, stiff-man syndrome, systemic lupus erythematosus, lupus erythematosus, takayasu arteritis, temporal arteristis/ giant cell arteritis, ulcerative colitis, uveitis, vasculitides such as dermatitis herpetiformis vasculitis, vitiligo, and Wegener's granulomatosis. Examples of inflammatory disorders include, but are not limited to, asthma, encephilitis, inflammatory bowel disease, chronic obstructive pulmonary disease (COPD), allergic disorders, septic shock, pulmonary fibrosis, undifferentitated spondyloarthropathy, undifferentiated arthropathy, arthritis, inflammatory osteolysis, and chronic inflammation resulting from chronic viral or bacteria infections. As described herein in Section 2.2.2, some autoimmune disorders are associated with an inflammatory condition. Thus, there is overlap between what is considered an autoimmune disorder and an inflammatory disorder. Therefore, some autoimniune disorders may also be characterized as inflammatory disorders. Examples of inflammatory disorders which can be prevented, treated or managed in accordance with the methods of the invention include, but are not limited to, asthma, encephilitis, inflammatory bowel disease, chronk~ obstructive , allergic disorders, septic shock, pulmonary fibrosis, undifferentitated spondyloarthropathy, undifferentiated arthropathy, arthritis, inflammatory osteolysis, and chronic inflammation resulting from chronic viral or bacteria infections. [00389] Molecules of the invention with variant Fe regions that have an enhanced affinity for FcyRflB and a decreased affinity for FcRIIIA relative to a comparable molecule comprising a wild-type Fe region can also be used to reduce the inflammation experienced by animals, particularly mammals, with inflammatory disorders. In a specific embodiment, a molecule of the invention reduces the inflammation in an animal by at least 99%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 6Q%, at least 50%, at least 45%, at least 40%, at least 45%, at least 35%, at least 30%, at least 25%, at least 20%, or at least 10% relative to the inflammation in an animal, which is not administered the said molecule. [003901 Molecules of the invention with variant Fe regions that have an enhanced affinity for FcRIIB and a decreased affinity for FcRIIIA relative to a comparable molecule comprising a wild-type Fc region can also be used to prevent the rejection of transplants. [00391] The invention further contemplates engineering any of the antibodies known in the art for the treatment and/or prevention of autoinimune disease or inflammatory disease, so that the antibodies comprise a variant Pc region comprising one or more amino acid modifications, which have been identified by the methods of the invention to have an enhanced affinity for FcRILB and a decreased affinity for FcRflIA relative to a comparable molecule comprising a wild type Fe region. A non-limiting example of the antibodies that are used for the treatment or prevention of inflammatory disorders which can be engineered according to the invention is presented in Table bA, and a non-limiting example of the antibodies that are used fQr the treatment or prevention of autoimmune disorder is presented in Table lOB. TABLE 1OA: ANTIBODIES FOR INFLAMMATORY DISEASES AND AUTOIMMUNE DISEASES THAT CAN ENGINEERED IN ACCORDANCE WITH TILE INVENTION. (Table Removed) TABLE lOB: ANTIBODIES FOR AUTOIMMUNE DISORDERS THAT CAN BE ENGINEERED IN ACCORDANCE WITH THE INVENTION (Table Removed) 5.4.2.1 IMMUNOMODULATORY AGENTS AND ANTI-INFLAMMATORY AGENTS [003921 The present invention provides methods of treatment for autoimmune diseases and inflammatory diseases comprising administration of the molecules with variant Fe regions having an enhanced affinity for FcyRIIB and a decreased affinity for FcRIIIA and/or FcRIIA in conjunction with other treatment agents. Examples of immunomodulatory agents include, but are not limited to, methothrexate, ENBREL, RBMICADE~', leflunomide, cyclophosphamide, cyclosporine A, and macrolide antibiotics (e.g., FK506 (tacrolimus)), methylprednisolone (MP), corticosteroids, steriods, mycophenolate mofetil, rapamycin (sirolimus), mizoribine, deoxyspergualin, brequinar, malononitriloamindes (e.g., leflunamide), T cell receptor modulators, and cytokine receptor modulators. [003931 Anti-inflammatory agents have exhibited success in treatment of inflammatory and autoimmune disorders and are now a common and a standard treatment for such disorders. Any anti-inflammatory agent well-known to one of skill in the art can be used in the methods of the invention. Non-limiting examples of anti-inflammatory agents include non-steroidal anti-inflammatory drugs (NSAIDs), steroidal anti-inflammatory drugs, geric agents, and methyl xanthines. Examples of NSAJDs include, but are not limited to, aspirin, ibuprofen, celecoxib (CELEBREX~), diclofenac (VOLTARENTh9, etodolac (LODINETM), fenoprofen (NALFONTh9, indomethacin (INDOC1N1), ketoralac (TORADOLTM), oxaprozin (DAYPROTNI), nabumentone (RELAFEN~), sulindac (cLINORILTM), tolmentin (TOLECTINTN9, rofecoxib (VIO)QC~), naproxen (ALE VETM, NAPROSYNThI), ketoprofen (ACTRON~) and nabumetone (RRLAFEN1'~'). Such NSAIDs function by inhibiting a cyclooxgenase enzyme (e.g., COX-1 and/or COX-2). Examples of steroidal anti-inflammatory drugs include, but are not limited to, glucocorticoids, dexamethasone (DECADRON~9, cortisone, hydrocortisone, prednisone (DELTASONEl~b9, prednisolone, triameinolone, azulfidine, and cicosanoids such as prostaglandins, Iliromboxanes, and leukotrienes. 5.4.3 INFECTIOUS DISEASE [00394] The invention also encompasses methods for treating or preventing an infectious disease in a subject comprising administering a therapeutically or prophylatically effective amount of one or more molecules of the invention. Infectious diseases that can be treated or prevented by the molecules of the invention are caused by infectious agents including but not limited to viruses, bacteria, fungi, protozae, and viruses. [09395] Viral diseases that can be treated or prevented using the molecules of the invention in conjunction with the methods of the present invention include, but are not limited to, those caused by hepatitis type A, hepatitis type B, hepatitis type C, influenza, varicella, adenovirus, herpes simplex type I (HSV-I), herpes simplex type II (HS V-il), rinderpest, rhinovirus, echovirus, rotavirus, respiratory syncytial virus, papilloma virus, papova virus, cytomegalovirus, echinovirus, arbovirus, huntavinis, coxsaclde virus, mumps virus, measles virus, rubella virus, polio virus, small pox, Epstein Ban virus, human immunodeficiency virus type 1 (HIV-1), human immunodeficiency virus type II (Hit V-Il), and agents of viral diseases such as viral miningitis, encephalitis, dengue or small pox. [003961 Bacterial diseases that can be treated or prevented using the molecules of the invention in conjunction with the methods of the present invention, that are caused by bacteria include, but are not limited to, niyeobacteria rickettsia, mycoplasma, neisseria , S. pneumonia, Borrelia burgdorferi (Lyme disease), Bacillus antracis (anthrax), tetanus, streptococcus, staphylococcus, mycobacterium, tetanus, pertissus, cholera, plague, diptheria, chiamydia, S. aureus and legionella. that can be treated or prevented using the molecules of the invention in conjunction with the methods of the present invention, that are caused by protozoa include, but are not limited to, leishmania, kokzidioa, trypanosoma or malaria. [00398] Parasitic diseases that can be treated or prevented using the molecules of the invention in conjunction with the methods of the present invention, that are caused by parasites include, but are not limited to, chiamydia and rickettsia. [003991 According to one aspect of the invention, molecules of the invention comprising variant Fe regions have an enhanced antibody effector function towards an infectious agent, e.g., a pathogenic protein, relative to a comparable molecule comprising a wild-type Fc region. Examples of infectious agents include but are not limited to bacteria (e.g., Escherichia coli, Kiebsiella pneumoniae, Staphylococcus aureu.v, &zteroc~ccus faeckds, Candida albi cans, Proteus vulgarLs~, Seaphyl~coccus viridans, and Pseudomonar aeruginosa), a pathogen, B-lymphotropic papovavirus (LPV); Bordatella pertussis; Borna Disease virus (I3DV); Bovine coronavirus; Chorionieningitis virus; Dengue virus; a virus, E. coli; Ebola; Echovirus 1; Echovirus-I I (By); Endotoxin (LPS); Enteric bacteria; Enteric Orphan virus; Enteroviruses ; Feline leukemia virus; Foot and mouth disease virus; Gibbon ape leukemia virus (GALY); Gram-negative bacteria ; Hdiobacter pylon; Hepatitis B virus (HBV); Herpes Simplex Virus; HIV-l; Human cytomegalovirus; Human coronovirus; Influenza A, B & C ; Legionella, Leishmania mexicana Listenia monocytogenes; Measles virus; Meningococcus; Morbilliviruses; Mouse hepatitis virus; Murine leukemia virus; Murine garuina herpes virus; Murine retrovirus; Murine coronavirus mouse hepatitis virus; Mycobacterium avium-M; Neissenia gonorrhoeae; Newcastle disease virus; Parvovirus B19; Plasmodium falciparum; Pox Virus; Pseudomonas; Rotavirus; Samonella typhiurium; Shigella; Streptococci; T-cell lymphotropic virus 1; Vaccinia virus). 100400] In a specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing phagocytosis and/or opsonization of the infectious agent causing the infectious disease. In another specific embodiment, molecules of the invention enhance the efficacy of treatment of an infectious disease by enhancing ADCC of infected cells causing the infectious disease. [00401] In some embodiments, the molecules of the invention may be administered in combination with a therapeutically or prophylactically effective amount of one or additional therapeutic agents known to those skilled in the art for the treatment and/or prevention of an infectious disease. The invention contemplates the use of the molecules of the invention in combination with antibiotics known to those skilled in the art for the treatment and or prevention of an infectious disease. Antibiotics that can be used in aan1whh4tli~uipl~ecules of the invention include, but are not liiiiitect to, macronae (e.g., tobramycin (Tobi®)), a cephalosporin (e.g., cephalexin (Keflex®), cephradine (Velosef®), cefuroxime (Ceftin®), cefprozil (Cefzil®), cef~clor (Cedar®), cefixime (Suprax®) or cefadroxil (Duricef1~))), a clarithromycin (e.g., clarithromycin (Biaxin®)), an erythromycin (e.g., erythromycin (EMycin®)), a penicillin (e.g., penicillin V (V-Cillin K® or Pen Vee K®)) or a quinolone (e.g., ofloxacin (Floxin®), ciprofloxacin (Cipro®) or norfioxacin (Noroxin®)),aminoglycoside antibiotics (e.g., apramycin, arbekacin, bambermycins, butirosin, dibekacin, neomycin, neomycin, undecylenate, netilmicin, paromomycin, ribostamycin, sisomicin, and spectinomycin), amphenicol antibiotics (e.g. azidamfenicol, chloramphenicol, florfenicol, and thiamphenicol), ansamycin antibiotics (e.g., rifamide and rifampin), carbacephems (e.g., loracarbef), carbapenems (e.g., biapenem and imipenem), cephalosporins (e.g., cefaclor, cefadroxil, cefamandole, cefatrizine, cefazedone, cefozopran, cef~,imizole, cefpiramide, and cefpirome), cephamycins (e.g., cefbuperazone, cefi~etazole, and cefminox), monobactams (e.g., aztreonam, carumonam, and tigemonarn), oxacephems (e.g., flomoxef, and moxalactam), penicillins (e.g., amdinocilhin, amdinocillin pivoxil, amoxicillin, bacampicillin, benzylpenicillinic acid, benzylpenicillin sodium, epicillin,, fenbenicillin, floxadilhin, penamccillin, penethamate hydriodide, penicillin o-benethaznine, penicillin 0, penicillin V. penicillin V benzatbine, penicillin V hydrabamine, penimepicydline, and phencihicillin potassium), lincosamides (e.g., clindamycin, and lincomycin), amphomycin, bacitracin, capreomycin, colistin, enduracidin, enviomycin, tetracyclines (e.g., apicycline, chlortetracydline, clomocycline, and demeclocycline), 2,4-diaminopyrimidines (e.g., brodimoprim), nitrofurans (e.g., furaltadone, and furazolium chloride), quinolones and analogs thereof (e.g., cinoxacin,, dlinafloxacin, fiumequine, and grepagloxacin), sulfonamides (e.g., acetyl sulfamethoxypyrazine, benzylsulfamide, noprylsulfamide, phthalylsulfacetamide, sulfachrysoidine, and sulf~cytine), sulfones (e.g., diathymosulfone, glucosulfone sodium, and solasulfone), cycloserine, mupirocin and tuberin. [004021 In certain embodiments, the molecules of the invention can be administered in combination with a therapeutically or prophylactically effective amount of one or more antifungal agents. Antifungal agents that can be used in combination with the molecules of the invention include but are not limited to amphotericin B, itraconazole, ketoconazole, fluconazole, intrathecal, flucytosine, miconazole, butoconazole, clotrimazole, nystatin, tereonazole, tioconazole, ciclopirox, econazole, haloprogrin, naftiline, terbinafine, undecylenate, and griseofuldin.. bodiments, the molecules of the invention can b&adimnistereci m combination with a therapeutically or prophylactically effective amount of one or more anti-viral agent Useful anti-viral agents that can be used in combination with the molecules of the invention include, but are not limited to, protease inhibitors, nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors and nucleoside analogs. Examples of antiviral agents include but are not limited to zidovudine, acyclovir, gangcyclovir, vidarabine, idoxuridine, trifluridine, and ribavirin, as well as foscarnet, amantadine, rimantadine, saquinavir, indinavir, amprenavir, lopinavir, ritonavir, the alpha-interferons; adefovir, clevadine, entecavir, pleconaril. 5.5 VACCINE THERAPY [004041 The invention further encompasses using a composition of the invention to induce an immune response against an antigenic or immunogenic agent, including but not limited to cancer antigens and infectious disease antigens (examples of which are disclosed infra). The vaccine compositions of the invention comprise one or more antigenic or inimunogenic agents to which an immune response is desired, wherein the one or more antigenic or immunogenic agents is coated with a variant antibody of the invention that has an enhanced affinity to FcRJIIA. Although not intending to be bound by a particular mechanism of action, coating an antigenic or immunogenic agent with a variant antibody of the invention that has an enhanced affinity to FcRIIIA, enhances the immune response to the desired antigenic or immunogenic agent by inducing humoral and cell-mediated responses. The vaccine compositions of the invention are particularly effective in eliciting an immune response, preferably a protective immune response against the antigenic or immunogenic agent [004051 In some embodiments, the antigenic or immunogenic agent in the vaccine compositions of the invention comprise a virus against which an immune response is desired. The viruses may be recombinant or chimeric, and are preferably attenuated. Production of recombinant, chimeric, and attenuated viruses may be performed using standard methods known to one skilled in the art. The invention encompasses a live recombinant viral vaccine or an inactivated recombinant viral vaccine to be formulated in accordance with the invention. A live vaccine may be preferred because multiplication in the host leads to a prolonged stimulus of similar kind and magnitude to that occurring in natural infections, and therefore, confers substantial, long-lasting immunity. Production of such live recombinant virus vaccine formulations may be accomplished using conventional pgation of the virus in cell culture or in the allantois ot the cluck embryo followed by purification. [004061 In a specific embodiment, the recombinant virus is non-pathogenic to the subject to which it is administered. In this regard, the use of genetically engineered viruses for vaccine purposes may require the presence of attenuation characteristics in these strains. The introduction of appropriate mutations (e.g., deletions) into the templates used for transfection may provide the novel viruses with attenuation characteristics. For example, specific missense mutations which are associated with temperature sensitivity or cold adaption can be made into deletion mutations. These mutations should be more stable than the point mutations associated with cold or temperature sensitive mutants and reversion frequencies should be extremely low. Recombinant DNA technologies for engineering recombinant viruses are known in the art and encompassed in the invention. For example, techniques for modifying negative strand RNA viruses are known in the art, see, e.g., U.S. Patent No. 5,166,057, which is incorporated herein by reference in its entirety. [004071 Alternatively, chimeric viruses with "suicide" characteristics may be constructed for use in the intradermal vaccine formulations of the invention. Such viruses would go through only one or a few rounds of replication within the host. When used as a vaccine, the recombinant virus would go through limited replication cycle(s) and induce a sufficient level of immi~ine response but it would not go further in the human host and cause disease. Alternatively, inactivated (killed) virus may be formulated in accordance with the invention. Inactivated vaccine formulations may be prepared using conventional techniques to "kill" the chimeric viruses. Inactivated vaccines are "dead" in the sense that their infectivity has been destroyed. Ideally, the infectivity of the virus is destroyed without affecting its immunogenicity. In order to prepare inactivated vaccines, the chimeric virus may be grown in cell culture or in the allantois of the chick embryo, purified by zonal ultracentrifugation, inactivated by formaldehyde or ~-propiolactone, and pooled. [004081 In certain embodiments, completely foreign epitopes, including antigens derived from other viral or non-viral pathogens can be engineered into the virus for use in the intradermal vaccine formulations of the invention. For example, antigens of non-related viruses such as HIV (gpl6O, gpl2O, gp4l) parasite antigens (e.g., malaria), bacterial or fungal antigens or tumor antigens can be engineered into the attenuated strain. [004091 Virtually any heterologous gene sequence may be constructed into the chimeric viruses of the invention for use in the intradermal vaccine formulations. Preferably, heterologous gene sequences are moieties and peptides that act as biological response modifiers. Preferably, epitopes that induce a protective immune response to any of that bind neutralizing antibodies maybe expresseci oy or as part of the chimeric viruses. For example, heterologous gene sequences that can be constructed into the chimeric viruses of the invention include, but are not limited to, influenza and parainfluenza hemagglutinin neuraminidase and fusion glycoproteins such as the HN and F genes of human PIV3. In yet another embodiment, heterologous gene sequences that can be engineered into the chimeric viruses include those that encode proteins with immuno-modulating activities. Examples of immuno-modulating proteins include, but are not limited to, cytokines, interferon type 1, gamma interferon, colony stimulating factors, interleukin -1, -2, -4, -5, -6, -12, and antagonists of these agents. [004101 In yet other embodiments, the invention encompasses pathogenic cells or viruses, preferably attenuated viruses, which express the variant antibody on their surface. [004111 In alternative embodiments, the vaecine compositions of the invention comprise a fusion polypeptide wherein an antigenic or immunogenic agent is operatively linked to a variant antibody of the invention that has an enhanced affinity for Fc~yRIllA. Engineering fusion polypeptides for use in the vaccine compositions of the invention is performed using routine recombinant DNA technology methods and is within the level of ordinary skill. [004121 The invention further encompasses methods to induce tolerance in a subject by administering a composition of the invention. Preferably a composition suitable for inducing tolerance in a subject, comprises an antigenic or immunogenic agent coated with a variant antibody of the invention, wherein the variant antibody has a higher affinity to FcRIIB. Although not intending to be bound by a particular mechanism of action, such compositions are effective in inducing tolerance by activating the FcRIIB mediatated inhibitory pathway. 5.6 COMPOSITIONS AND METHODS OF ADMINISTERING [00413] The invention provides methods and pharmaceutical compositions comprising molecules of the invention (I.e., antibodies, polypeptides) comprising variant Fe regions. The invention also provides methods of treatment, prophylaxis, and amelioration of one or more symptoms associated with a disease, disorder or infection by administering to a subject an effective amount of a fusion protein or a conjugated molecule of the invention, or a pharmaceutical composition comprising a fusion protein or a conjugated molecule of the invention. In a preferred aspect, an antibody, a fusion protein, or a conjugated molecule, is substantially purified (I.e., substantially free from substances that limit its effect or produce undesired side-effects). In a specific embodiment, the subject is such as non-primate (e.g., cows, pigs, norses, cats, dogs, rats etc.) and a primate (e.g., monkey such as, a cynomolgous monkey and a human). In a preferred embodiment, the subject is a human. In yet another preferred embodiment, the antibody of the invention is from the same species as the subject. [00414] Various delivery systems are known and can be used to administer a composition comprising molecules of the invention (i.e., antibodies, polypeptides), comprising variant Fc regions, e.g., encapsulation in liposomes, microparticles, microcapsules, recombinant cells capable of expressing the antibody or fusion protein, receptor-mediated endocytosis ($~ee, e.g., Wu and Wu, 1987, J. Biol. Chem. 262:4429-4432), construction of a nucleic acid as part of a retroviral or other vector, etc. Methods of administering a molecule of the invention include, but are not limited to, parenteral administration (e.g., intradermal, intramuscular, intraperitoneal, intravenous and subcutaneous), epidural, and mucosal (e.g., intranasal and oral routes). In a specific embodiment, the molecules of the invention are administered intramuscularly, intravenously, or subcutaneously. The compositions may be administered by any convenient route, for example, by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, rectal and intestinal mucosa, etc.) and may be administered together with other biologically active agents. Administration can be systemic or local. In addition, puimonary administration can also be employed,, e.g., by use of an inhaler or nebulizer, and formulation with an aerosolizing agent. See, e.g., U.S. Patent Nos. 6,019,968; 5,985, 320; 5,985,309; 5,934,272; 5,874,064; 5,855,913; 5,290,540; and 4,880,078; and PCT Publication Nos. WO 92/19244; WO 97/32572; WO 97/44013; WO 98/3 1346; and WO 99/66903, each of which is incorporated herein by reference in its entirety. [00415]The invention also provides that the molecules of the invention (i.e., antibodies, polypeptides) comprising variant Fc regions, are packaged in a hermetically sealed container such as an ampoule or sachette indicating the quantity of antibody. In one embodiment, the molecules of the invention are supplied as a dry sterilized lyophilized powder or water free concentrate in a hermetically sealed container and can be reconstituted, e.g., with water or saline to the appropriate concentration for administration to a subject. Preferably, the molecules of the invention are supplied as a dry sterile lyophilized powder in a hermetically sealed container at a unit dosage of at least 5 mg, more preferably at least 10mg, at least 15 mg, at least 25 mg, at least 35 mg, at least 45 mg, at least 50 mg, or at least 75 mg. The lyophilized molecules of the invention should be stored at between 2 and 80C in their original container and the molecules should be administered within 12 1ee~ablvkthi~i.~ hours, within 5 hours, within 3 hours, or within 1 hour after being reconstituted. In an alternative embodiment, molecules of the invention are supplied in liquid form in a hermetically sealed container indicating the quantity and concentration of the molecule, fusion protein, or conjugated molecule. Preferably, the liquid form of the molecules of the invention are supplied in a hermetically sealed container at least 1 mg/mi, more preferably at least 2.5 mg/mi, at least 5 mg/mI, at least 8 mg/mI, at least 10 mg/ml, at least 15 mg/kg, at least 25 mg/ml, at least 50mg/mi, at least 100 mg/mI, at least 150 mg/mI, at least 200 mg/mi of the molecules. [004161 The amount of the composition of the invention which will be effective in the treatment, prevention or amelioration of one or more symptoms associated with a disorder can be determined by standard clinical techniques. The precise dose to be employed in the formulation will also depend on the route of administration, and the seriousness of the condition, and should be decided according to the judgment of the practitioner and each patient's circumstances. Effective doses may be extrapolated from dose-response curves derived from in vitro or animal model test systems. [00417] For antibodies encompassed by the invention, the dosage administered to a patient is typically 0.0001 mg/kg to 100 mg/kg of the patient's body weight. Preferably, the dosage administered to a patient is between 0.0001 mg/kg and 20 mg/kg, 0.0001 mg/kg and 10mg/kg, 0.0001 mg/kg and 5 mg/kg, 0.0001 and 2 mg/kg, 0.0001 and 1 mg/kg, 0.0001 mg/kg and 0.75 mg/kg, 0.0001 mg/kg and 0.5 mg/kg, 0.0001 mg/kg to 0.25 mg/kg, 0.0001 to 0.15 mg/kg, 0.0001 to 0.10 mg/kg, 0.001 to 0.5 mg/kg, 0.01 to 0.25 mg/kg or 0.01 to 0.10 mg/kg of the patient's body weight. Generally, human antibodies have a longer half-life within the human body than antibodies from other species due to the immune response to the foreign polypeptides. Thus, lower dosages of human antibodies and less frequent administration is often possible. Further, the dosage and frequency of administration of antibodies of the invention or fragments thereof may be reduced by enhancing uptake and tissue penetration of the antibodies by modifications such as, for example, lipidation. [00418] In one embodiment, the dosage of the molecules of the invention administered to a patient are 0.01mg to 1000mg/day, when used as single agent therapy. In another embodiment the molecules of the invention are used in combination with other therapeutic compositions and the dosage administered to a patient are lower than when said molecules are used as a single agent therapy. [004191 In a specific embodiment, it may be desirable to administer the pharmaceutical compositions of the invention locally to the area in need of treatment this may be achieved by, for example, and not by way of limitation, local infusion, by injection, said implant being of a porous, non-porous, or gelatinous material, including membranes, such as sialastic membranes, or fibers. Preferably, when administering a molecule of the invention, care must be taken to use materials to which the molecule does not absorb. [00420] In another embodiment, the compositions can be delivered in a vesicle, in particular a liposome (See Langer, Science 249:1527-1533 (1990); Treat eta!., in Liposomes in the Therapy of Infectious Disease and Cancer Lopez-Berestein and Fidier (eds.), Liss, New York, pp. 353- 365 (1989); Lopez-Berestein, ibid., pp. 3 17-327; see generally ibid.). 1004211 In yet another embodiment, the compositions can be delivered in a confrQlled release or sustained release system. Any technique known to one of skill in the art can be used to produce sustained release formulations comprising one or more molecules of the invention. See, e.g., U.S. Patent No. 4,526,938; PCT publication WO 91/05548; PCT publication WO 96/20698; Ning eta!., 1996, "Intratumoral Radioimmunotheraphy of a Human Colon Cancer Xenograft Using a Sustained-Release Gel," Radiotherapy & Oncology 39:179-189, Song eta!., 1995, "Antibody Mediated Lung Targeting of Long-Circulating ~mulsions," PDA Journal of Phannaceutical Science & Technology 50:372-397; Cleek et a!., 1997, "Biodegradable Polymeric Carriers for a bFGF Antibody for Cardiovascular Application," Pro. Int'l. Symp. Control. Re!. Bioact. Mater. 24:853-854; and Lam eta!., 1997, "Microencapsulation of Recombinant Humanized Monoclonal Antibody for Local Delivery," Proc. Int'l. Symp. Control Re!. .Bioact. Mater. 24:759-760, each of which is incorporated herein by reference in its entirety. In one embodiment, a pump may be used in a controlled release system (See Langer, supra; ~efton, 1987, CRC Crit. Ref Biomedl Eng. 14:20; Buchwald et at, 1980, Surgery 88:507; and Saudek eta!., 1989, N. Eng!. J Med 321:574). In another embodiment, polymeric materials can be used to achieve controlled release of antibodies (see e.g., Medical ADplications of Controlled Release Langer and Wise (eds.), CRC Pres., Boca Raton, Florida (1974); Controlled Drug Bioavailability, Drug Product Design and Performance, Smolen and Ball (eds.), Wiley. New York (1984); Ranger and Peppas, 1983, J., Macromol. Sc!. Rev. Macromol. Chem~ 23:61; See also Levy et aL, 1985, Science 228:190; During eta!., 1989, Ann. Neurol. 25:351; Howard et al., 1989,J. Neurosurg. 7 1:105); U.S. Patent No. 5,679,377; U.S. Patent No. 5,916,597; U.S. PatentNo. 5,912,015; U.S. Patent No. 5,989,463; U.S. Patent No. 5,128,326; PCTPublicationNo. WO 99/15154; and PCT Publication No. WO 99/20253). Examples of polymers used in sustained release formulations include, but are not limited to, poly(2-hydroxy ethyl methacrylate), poly(methyl methacrylate), poly(acrylic acid), ppltu(~tl.~ainne.uoowinvi~acetate), poly(methacrylic acid), polyglycolides (PLG), polyanhydrides, poly(N-vinyl pyrrolidone), poly(vinyl alcohol), polyacrylamide, poly(ethylene glycol), polylactides (PtA), poly(lactide-co-glycolides) (PLGA), and polyorthoesters. In yet another embodiment, a controlled release system can be placed in proximity of the therapeutic target (e.g., the lungs), thus requiring only a fraction of the systemic dose (see, e.g., Goodson, in Medical Applications of Controlled Release, sup ra, vol.2, pp. 115-138 (1984)). In another embodiment, polymeric compositions useful as controlled release implants are iise4 according to Dunn eta!. (See U.S. 5,945,155). This particular method is based upon the therapeutic effect of the in situ controlled release of the bioactive material from the polymer system. The implantation can generally occur anywhere within the body of the patient in need of therapeutic treatment. In another embodiment, a non-polymeric sustained delivery system is used, whereby a non-polymeric implant in the body of the subject is used as a drug delivery system. Upon implantation in the body, the organic solvent of the implant will dissipate, disperse, or leach from the composition into surrounding tissue fluid, and the non-polymeric material will gradually coagulate or precipitate to form a solid, microporous matrix (See U.S. 5,888,533). [004221 Controlled release systems are discussed in the review by Langer (1990, Science 249:1527-1533). Any technique known to one of skill in the art can be used to produce sustained release formulations comprising one or more therapeutic agents of the invention. See, e.g., U.S. Patent No. 4,526,938; International Publication Nos. WO 91/05548 and WO 96/20698; Ning eta!., 1996, Radiotherapy & Oncology 39:179-189; Song eta?., 1995, PDA Journal of Pharmaceutical Science & Technology 50:372-397; Cleek eta!., 1997, Pro. Int'l. Symp. Control. Re!. Ejoact. Mater. 24:853-854; and Lam et al., 1997, Proc. Int'l. Symp. Control Re!. Bloact. Mater. 24:759-760, each of which is incorporated herein by reference in its entirety. [004231 In a specific embodiment where the composition of the invention is a nucleic acid encoding an antibody, the nucleic acid can be administered in vivo to promote expression of its encoded antibody, by constructing it as part of an appropriate nucleic acid expression vector and administering itso that it becomes intracellular, e.g., by use of a retroviral vector (See U.S. Patent No. 4,980,286), or by direct injection, or by use of microparticle bombardment (e.g., a gene gun; Biolistic, Dupont), or coating with lipids or cell-surface receptors or transfecting agents, or by administering it in linkage to a homeobox-like peptide which is known to enter the nucleus (See e.g., Joliot eta!., 1991, Proc. Nat!. Acad Sci. U5~A 88:1864-1868), etc. Alternatively, a nucleic acid can be and incorporated within host cell DNA for expression by homologous recombination. [00424] For antibodies, the therapeutically or prophylactically effective dosage administered to a subject is typically 0.1 mg/kg to 200 mg/kg of the subject's body weight. Preferably, the dosage administered to a subject is between 0.1 mg/kg and 20 mg/kg of the subject's body weight and more preferably the dosage administered to a subject is between 1 mg/kg to 10 mg/kg of the subject's body weight. The dosage and frequency of administration of antibodies of the invention may be reduced also by enhancing uptake and tissue penetration (e.g., into the lung) of the antibodies or fusion proteins by modifications such as, for example, lipidation. [00425] Treatment of a subject with a therapeutically or prophylactically effective amount of molecules of the invention can include a single treatment or, preferably, can include a series of treatments. In a preferred example, a subject is treated with molecules of the invention in the range of between about 0.1 to 30 mg/kg body weight, one time per week for between about 1 to 1 () weeks, preferably between 2 to 8 weeks, more preferably between about 3 to 7 weeks, and even more preferably for about 4, 5, or 6 weeks. In other embodiments, the pharmaceutical compositions of the invention are administered once a day, twice a day, or three times a day. In other embodiments, the pharmaceutical compositions are administered once a week, twice a week, once every two weeks, once a month, once every six weeks, once every two months, twice a year or once per year. It will also be appreciated that the effective dosage of the molecules used for treatment may increase or decrease over the course of a particular treatment. 5.6.1 PHARMACEUTICAL COMPOSITIONS [00426] The compositions of the invention include bulk drug compositions useful in the manufacture of pharmaceutical compositions (e.g., impure or non-sterile compositions) and pharmaceutical compositions (i.e., compositions that are suitable for administration to a subject or patient) which can be used in the preparation of unit dosage forms. Such compositions comprise a prophylactically or therapeutically effective amount of a prophylactic and/or therapeutic agent disclosed herein or a combination of those agents and a pharmaceutically acceptable carrier. Preferably, compositions of the invention comprise a prophylactically or therapeutically effective amount of one or more molecules of the invention and a pharmaceutically acceptable carrier. [004271 In one particular embodiment, the pharmaceutical composition comprises a therapeutically effective amount of one or more molecules of the invention comprising a rient.fr reaiem~ whe~ojn said variant Fc region binds FcRJIIA and/or FcRIIA with a greater affinity than a comparable molecule comprising a wild-type Fc region binds FcRIIIA and/or FcRIIA and/or said variant Pc region mediates an effector function at least 2-fold more effectively than a comparable molecule comprising a wild-type Pc region, and a pharmaceutically acceptable carrier. In another embodiment, the pharmaceutical composition comprises a therapeutically effective amount of one or more molecules of the invention comprising a variant Fe region, wherein said variant Fe region binds FcRll.IA with a greater affinity than a comparable molecule comprising a wild-type Fe region binds FcRIIIA, and said variant Fe region binds FcyRflB with a lower affinity than a comparable molecule comprising a wild-type Fe region binds FcRIIB, and/or said variant Fe region mediates an effector function at least 2-fold more effectively than a comparable molecule comprising a wild-type Fe region, and a pharmaceutically acceptable carrier. In another embodiment, said pharmaceutical compositions further comprise one or more anti-cancer agents. [004281 The invention also encompasses pharmaceutical compositions comprising a therapeutic antibody (e.g., tumor specific monoclonal antibody) that is specific for a particular cancer antigen, comprising one or more amino acid modifications in the Fe region as determined in accordance with the instant invention, and a pharmaceutically acceptable carrier. [00429] In a specific embodiment, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term "carrier" refers to a diluent, adjuvant (e.g., Freund's adjuvant (complete and incomplete), excipient, or vehicle with which the therapeutic is administered. Such pharmaceutical carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical excipients include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. The composition, if desired, can also contain minor amounts of wetting or emulsifying agents, or pH buffering agents. These compositions can take the form of solutions, ens~emulsioa~ ~blets, pills, capsules, powders, sustained-release formulations and the like. [00430] Generally, the ingredients of compositions of the invention are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water free concentrate in a hermetically sealed container such as an anipoule or sachette indicating the quantity of active agent. Where the composition is to be administered by infusion, it can be dispensed with an infusion bottle containing sterile pharmaceutical grade water or saline. Where the composition is administered by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients may be mixed prior to administration. [0Q431] The compositions of the invention can be formulated as neutral or salt forms. Pharmaceutically acceptable salts include, but are not limited to those formed with anions such as those derived from hydrochloric, phosphoric, acetic, oxalic, tartaric acids, etc., and those formed with cations such as these derived from sodium, potassium, ammonium, calcium, ferric hydroxides, isopropylamine, triethylamine, 2-ethylamino ethanol, histidine, procaine, etc. 5.6.2 GENE TH1~RAPY [00432] In a specific embodiment, nucleic acids comprising sequences encoding molecules of the invention, are administered to treat, prevent or ameliorate one or more symptoms associated with a disease, disorder, or infection, by way of gene therapy. Gene therapy refers to therapy performed by the administration to a subject of an expressed or expressible nucleic acid. In this embodiment of the invention, the nucleic acids produce their encoded antibody or fusion protein that mediates a Therapeutic or prophylactic effect. [00433] Any of the methods for gene therapy available in the art can be used according to the present invention. Exemplary methods are described below. [00434] For general reviews of the methods of gene therapy, see Goldspiel et at, 1993, ClinIcal Pharmacy 12:488-505; Wu and Wu, 1991, Biotherapy 3:87-95; Tolstoshev, 1993, Ann. Rev. PharmacoL Toxicol. 32:573-596; Mulligan, Science 260:926-932 (1993); and Morgan and Anderson, 1993, Ann. Rev. Biochem. 62:191-217; May, 1993, TIBTECH 11(5): 155-215. Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel eta!. (eds.), Current Protocols in Molecular Biology. John Wiley & Sons, NY (1993); and Kriegler, Gene Transfer and Exrression. A Laboratory Manual. Stockton Press, NY (1990). aspect, a composition of the invention comprises nucleic acids encoding an antibody, said nucleic acids being part of an expression vector that expresses the antibody in a suitable host. In particular, such nucleic acids have promoters, preferably heterologous promoters, operably linked to the antibody coding region, said promoter being inducible or constitutive, and, optionally, tissue-specific. In another particular embodiment, nucleic acid molecules are used in which the antibody coding sequences and any other desired sequences are flanked by regions that promote homologous recombination at a desired site in the genome, thus providing for intrachromosomal expression of the antibody encoding nucleic acids (Koller and Smithies, 1989, Proc. Nati. Acad as'ci. LISA 86:8932-8935; and ZijlstraetaL, 1989,Nature 342:435-438). [004361 In another preferred aspect, a composition of the invention comprises nucleic acids encoding a fusion protein, said nucleic acids being a part of an expression vector that expresses the fusion protein in a suitable host. In particular, such nucleic acids have promoters, preferably heterologous promoters, operably linked to the coding region of a fusion protein, said promoter being inducible or constitutive, and optionally, tissue-specific. In another particular embodiment, nucleic acid molecules are used in which the coding sequence of the fusion protein and any other desired sequences are flanked by regions that promote homologous recombination at a desired site in the genome, thus providing for intrachromosomal expression of the fusion protein. [00437] Delivery of the nucleic acids into a subject may be either direct, in which case the subject is directly exposed to the nucleic acid or nucleic acid-carrying vectors, or indirect, in which case, cells are first transformed with the nucleic acids in vitro, then transplanted into the subject These two approaches are known, respectively, as in viva or ex vivo gene therapy. [00438] In a specific embodiment, the nucleic acid sequences are directly administered in vivo, where it is expressed to produce the encoded product This can be accomplished by any of numerous methods known in the art, e.g., by constructing them as part of an appropriate nucleic acid expression vector and administering itso that they become intracellular, e.g., by infection using defective or attenuated retroviral or other viral vectors (see U.S. Patent No. 4,980,286), or by direct injection of naked DNA, or by use of mieroparticle bombardment (e.g., a gene gun; Biolistic, Dupont), or coating with lipids or cell-surface receptors or transfecting agents, encapsulation in liposomes, microparticles, or microcapsules, or by administering them in linkage to a peptide which is known to enter the nucleus, by administering it in linkage to a ligand subject to receptor-mediated endocytosis (See, e.g., Wu and Wu, 1987, .L Biol. Chem. 262:4429-4432) (which can be used to target the receptors), etc. In another embodiment, nucleic acid¬ligand complexes can be formed in which the ligand comprises a fusogenic viral peptide to disrupt endosomes, allowing the nucleic acid to avoid lysosomal degradation. In yet another embodiment, the nucleic acid can be targeted in vivo for cell specific uptake and expression, by targeting a specific receptor (See, e.g., PCT Publications WO 92/06180; WO 92/22635; W092/203 16; W093/14188; WO 93/2022 1). Alternatively, the nucleic acid can be introduced intracelli.darly and incorporated within host cell DNA for expression, by homologous recombination (Koller and Smithies, 1989, Proc Nati. Acad Sci. USA 86:8932-8935; and Zijlstra et al.; 1989, Nature 342:435-438). [004391 In a specific embodi~nent, viral vectors that contain nucleic acid sequences encoding a molecule of the invention (e.g., an antibody or a fusion protein) are used. For example, a retroviral vector can be used (See Miller et a)., 1993, Meth. Ensymol. 217:581-599). These retroviral vectors contain the components necessary for the correct packaging of the viral genome and integration into the host cell DNA. The nucleic acid sequences encoding the antibody or a fusion protein to be used in gene therapy are cloned into one or more vectors, which facilitates delivery of the nucleotide sequence into a subject. More detail about retroviral vectors can be found in J3oesen et al., (1994, Biotherapy 6:291-302), which describes the use of a refroviral vector to deliver the mdr I gene to hematopoictic stem cells in order to make the stem cells more resistant to chemotherapy. Other references illustrating the use of retroviral vectors in gene therapy are: Clowes et a!., 1994, J. Clin. Invest. 93:644-651; Klein eta)., 1994, Blood 83:1467-1473; Salmons and Gunzberg, 1993, Human Gene Therapy 4:129-141; and Grossman and Wilson, 1993, Curr. Opin. in Genetics and Devel. 3:1 10-1 14. 100440] Adenoviruses are other viral vectors that can be used in gene therapy. Adenoviruses are especially attractive vehicles for delivering genes to respiratory epitheli& Adenoviruses naturally infect respiratory epithelia where they cause a mild disease. Other targets for adenovirus-based delivery systems are liver, the central nervous system, endothelial cells, and muscle. Adenoviruses have the advantage of being capable of infecting non-dividing cells. Kozarsky and Wilson (Current Opinion in Genetics and Development 3:499-503, 1993, present a review of adenovirus-based gene therapy. Bout et a!., (Human Gene Therapy, 5:3-10, 1994) demonstrated the use of adenovirus vectors to transfer genes to the respiratory epithelia of rhesus monkeys. Other instances of the use of adenoviruses in gene therapy can be found in Rosenfeld et aL, 1991, Science 252:431-434; Rosenfeldetat, 1992, Cell68:143-155;MastrangelietaL, 1993,.! Clin. Invest. 91:225- 2~4zPublii~atiea~y094/l2649; and Wang et al., 1995, Gene Therapy 2:775-783. In a preferred embodiment, adenovirus vectors are used. [00441] Adeno-associated virus (AAV) has also been proposed for use in gene therapy (see, e.g. ,Walsh et at., 1993, Proc. Soc. Exp. Blot. Med 204:289-300 and U.S. Patent No. 5,436,146). [00442] Another approach to gene therapy involves transferring a gene to cells in tissue culture by such methods as electroporation, lipofection, calcium phosphate mediated transfection, or viral infection. Usually, the method of transfer includes the transfer of a selectable marker to the cells. The cells are then placed under selection to isolate those cells that have taken up and are expressing the transferred gene. Those cells are then delivered to a subject. [00443] In this embodiment, the nucleic acid is introduced into a cell prior to administration in vivo of the resulting recombinant cell. Such introduction can be carried out by any method known in the art, including but not limited to, transfection, electroporation, microinjection, infection with a viral or bacteriophage vector, containing the nucleic acid sequences, cell fusion, chromosome-mediated gene transfer, microcellmediated gene transfer, splieroplast fusion, etc. Numerous techniques are known in the art for the introduction of foreign genes into cells (See, e.g., Loeffler and Behr, 1993, Meth. EnzymoL 217:599-618, Cohen et aL, 1993, Meth Enzymol. 217:618-644; and Cli. Pharma. Ther. 29:69-92, 1985) and may be used in accordance with the present invention, provided that the necessary developmental and physiological functions of the recipient cells are not disrupted. The technique should provide for the stable transfer of the nucleic acid to the cell, so that the nucleic acid is expressible by the cell and preferably heritable and expressible by its cell progeny. [00444] The resulting recombinant cells can be delivered to a subject by various methods known in the art. Recombinant blood cells (e.g., hematopoietic stem or progenitor cells) are preferably administered intravenously. The amount of veils envisioned for use depends on the desired effect, patient state, etc, and can be determined by one skilled in the art. [00445] Cells into which a nucleic acid can be introduced for purposes of gene therapy encompass any desired, available cell type, and include but are not limited to epithelial cells, endothelial cells, keratinocytes, fibroblasts, muscle cells, hepatocytes; blood cells such as T lymphocytes, B lymphocytes, monocytes, niacrophages, neutrophils, eosinophils, megakaryocytes, granulocytes; various stem or progenitor cells, in particular cells, e.g., as obtained from bone marrow, umbilical cord blood, peripheral blood, fetal liver, etc. (00446] In a preferred embodiment, the cell used for gene therapy is autologous to the subject. [00447] In an embodiment in which recombinant cells are used in gene therapy, nucleic acid sequences encoding an antibody or a fusion protein are introduced into the cells such that they are expressible by the cells or their progeny, and the recombinant cells are then administered in vivo for therapeutic effect. In a specific embodiment, stem or progenitor cells are used. Any stem and/or progenitor cells which can be isolated and maintained in vitro can potentially be used in accordance with this embodiment of the present invention (See e.g., PCT Publication WO 94/08598; Stemple and Anderson, 1992, Cell 7 1:973-985; Rheinwald, 1980, Meth. Cell Bio. 21A:229; and Pittelkow and Scott, 1986, Mayo Clinic Proc. 6 1:771). (00448] In a specific embodiment, the nucleic acid to be introduced for purposes of gene therapy comprises an inducible promoter operably linked to the coding region, such that expression of the nucleic acid is controllable by controlling the presence or absence of the appropriate inducer of transcription. 5.6.3 KITS [004491 The invention provides a pharmaceutical pack or kit comprising one or more containers filled with the molecules of the invention (I.e., antibodies, polypeptides comprising variant Fc regions). Additionally, one or more other prophylactic or therapeutic agents useful for the treatment of a disease can also be included in the pharmaceutical pack or kit. The invention also provides a pharmaceutical pack or kit comprising one or more containers filled with one or more of the ingredients of the pharmaceutical compositions of the invention. Optionally associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufucture, use or sale of pharmaceuticals or biological products, which notice reflects approval by the agency of manufacture, use or sale for human administration. [00450] The present invention provides kits that can be used in the above methods. In one embodiment, a kit comprises one or more molecules of the invention. In another embodiment, a kit further comprises one or more other prophylactic or therapeutic agents useful for the treatment of cancer, in one or more containers. In another embodiment, a kit further comprises one or more cytotoxic antibodies that bind one or more cancer antigens associated with cancer. In certain embodiments, the other prophylactic or therapeutic agent 2sR~~mtherap~uticdtr other embodiments, the prophylactic or therapeutic agent is a biological or hormonal therapeutic. 5.7 CHARACTERIZATION AND DEMONSTRATION OF THERAPEUTIC UTILITY [00451] Several aspects of the pharmaceutical compositions, prophylactic, or therapeutic agents of the invention are preferably tested in vitro, in a cell culture system, and in an animal model organism, such as a rodent animal model system, for the desired therapeutic activity prior to use in humans. For example, assays which can be used to determine whether administration of a specific pharmaceutical composition is desired, include cell culture assays in which a patient tissue sample is grown in culture, and exposed to or otherwise contacted with a pharmaceutical composition of the invention, and the effect of such composition upon the tissue sample is observed. The tissue sample can be obtained by biopsy from the patient. This test allows the identification of the therapeutically most effective prophylactic or therapeutic molecule(s) for each individual patient. In various specific embodiments, in vitro assays can be canied out with representative cells of cell types involved in an autoimmune or inflammatory disorder (e.g., T cells), to determine if a pharmaceutical composition of the invention has a desired effect upon such cell types. [00452] Combinations of prophylactic and/or therapeutic agents can be tested in suitable animal model systems prior to use in humans. Such animal model systems include, but are not limited to, rats, mice, chicken, cows, monkeys, pigs, dogs, rabbits, etc. Any animal system well-known in the art may be used. In a specific embodiment of the invention, combinations of prophylactic and/or therapeutic agents are tested in a mouse model system. Such model systems are widely used and well-known to the skilled artisan. Prophylactic and/or therapeutic agents can be administered repeatedly. Several aspects of the procedure may vary. Said aspects include the temporal regime of administering the prophylactic and/or therapeutic agents, and whether 8uch agents are administered separately or as an admixture. [00453] Preferred animal models for use in the methods of the invention are, for example, tranagenic mice expressing human Fc'yRs on mouse effector cells, e.g., any mouse model described in U.S. 5,877,396 (which is incorporated herein by reference in its entirety) can be used in the present invention. Transgenic mice for use in the methods of the invention include, but are not limited to, mice carrying human FoyRJIIA; mice carrying human FoyRIIA; mice carrying human FcTRflB and human FcyRflIA; mice carrying human FcyRflB and human FeTRJIA. mutations showing the highest levels of activity in the Iimctional assays described above will be tested for use in animal model studies prior to use in humans. Antibodies harboring the Fc mutants identified using the methods of the invention and tested in ADCC assays, including ch4D5 and ch520C9, two anti-Erb-B2 antibodies, and chCC49, an anti-TAG72 antibody, are preferred for use in animal models since they have been used previously in xenograft mouse model (Hudsiak et al., 1989, Mel. Cell Biol. 9: 1165-72; Lewis et aL, 1993, Cancer Immzrnol. immunother. 37: 255-63; Bergman et al., 2001 Clin. Cancer Re:. 7: 2050-6; Johnson et al., 1995, Anticancer Re:. 13 87-93). Sufficient quantities of antibodies may be prepared for use in animal models using methods described supra, for example using mammalian expression systems and IgG purification methods disclosed and exemplified herein. A typical experiment requires at least about 5.4 mg of mutant antibody. This calculation is based on average quantities of wild type antibody required to protect 8-1030 g mice following a loading dose of 4 ~g/g and a weekly maintenance dose, 2 µg/g, for ten weeks. invention encompasse tumor cell lines as a source for xenografl tumors, such as SK-BR-3, BT474 and HT29 cells which are derived from patients with breast adenocarcinoma. These cells have both Erb-B2 and the prolactin receptors on their surface. The SK-BR-3 cells have been used successfully in both ADCC and xenograft tumor models. In other assays OVCAR3 cells derived from a human ovarian adenocarcinoma may be used. These cells express the antigen TAG72 on the cell surface and can be used in conjunction with the chCC49 antibody. The use of different antibodies and multiple tumor models will circumvent loss of any specific mutations due to an antibody specific Fe mutant incompatibility. 1004551 Mouse xenograft models may be used for examining efficacy of mouse antibodies generated against a tumor specific target based on the affinity and specificity of the CDR regions of the antibody molecule and the ability of the Fc region of the antibody to elicit an immune response (Wu et al., 2001, Trends Cell Biol. 1l:S2-9). Trausgenic mice expressing human FcyRs on mouse effector cells are unique and are tailor-made animal models to test the efficacy of human Fc-FcyR interactions. Pairs of FoyRIJIA, FcyRfllB and FcyRIIA transgenic mouse lines generated in the lab of Dr. Jel~ey Ravetch (Through a licensing agreement with Rockefeller U. and Sloan Kettering Cancer center) can be used such as those listed in the Table 11 below. (Table Removed) [00456] Preferably Fe mutants showing both enhanced binding to Fc'yRIJIA and reduced binding to FcRIIB, increased activity in ADCC and phagocytosis assays are tested in animal model experiments. The animal model experiments examine the increase in efficacy of Fe mutant bearing antibodies in FoRIIIA transgenic, nude mCDl6A knockout mice compared to a control which has been administered native antibody. Preferably, groups of 8-10 mice are examined using a standard protocol. An exemplary animal model experiment may comprise the following steps: in a breast cancer model, —2 x 106 SK-BR-3 cells are injected subcutaneously on day 1 with 0.1 mL PBS mixed with Matrigel (Becton Dickinson). Initially a wild type chimeric antibody and isotype control are administered to establish a curve for the predetermined therapeutic dose, intravenous injection of 4D5 on day I with an initial dose of 4 ~ig/g followed by weekly injections of 2 ~g/g. Tumor volume is monitored for 6-8 weeks to measure progress of the disease. Tumor volume should increase linearly with time in animals injected with the isotype control. In contrast very little tumor growth should occur in the group injected with 4D5. Results from the standard dose study are used to set an upper limit for experiments testing the Fe mutants. These studies are done using subtherapeutic doses of the Fc mutant containing antibodies. A one tenth dose was used on xenograft models in experiments done in FcRflB knockout mice, see, Clynes et al., 2000, Nat. Med. 6: 443-6, with a resultant block in tumor cell growth. Since the mutants ef the invention preferrably show an increase in FcyRflIA~aetivation and reduction in FcRIIB binding the mutants are examined at one tenth therapeutic dose. Examination of tumor size at different interval.~ indicates the efficacy of the antibodies at the lower dose. Statistical analysis of the data using t test provides a way of determining if the data is significant. Fc mutants that show increased efficacy are tested at incrementally lower doses to determine the smallest possible dose as a measure of their efficacy. [00457] The anti-inflammatory activity of the combination therapies of invention can be determined by using various experimental animal models of inflammatory arthritis known in the art and described in Crofford L.J. and Wilder RL, "Arthritis and Autoimmunity in Animals", in Arthritis and Allied Conditions: A Textbook of Rheumatology, McCarty et al.(eds.), Chapter 30 (Lee and Febiger, 1993). Experimental and spontaneous animal models of inflammatory arthritis and autoimmune rheumatic diseases can also be used to assess the anti-inflammatory activity of the combination u,~repae&et in~atien~ The following are some assays provided as examples, and not by limitation. 100458] The principle animal models for arthritis or inflammatory disease known in the art and widely used include: adjuvant-induced arthritis rat models, collagen-induced arthritis rat and mouse models and antigen-induced arthritis rat, rabbit and hamster models, all described in Crofford L.J. and Wilder R.L., "Arthritis and Autoimmunity in Animals", in Arthritis and Allied Conditions: A Textbook of Rheumatology, McCarty et al.(eds4, Chapter 30 (Lee and Febiger, 1993), incorporated herein by reference in its entirety. [004~9] The anti-inflammatory activity of the combination therapies of invention can be assessed using a carrageenan-induced arthritis rat model. Carrageenan-induced arthritis has also been used in rabbit, dog and pig in studies of chronic arthritis or inflammation. Quantitative histomorphometric assessment is used to determine therapeutic efficacy. The methods for using such a carrageenan-induced arthritis model is described in Hansra P. et al., "Carrageenan-Induced Arthritis in the Rat ," Inflammation, 24(2): 141-155, (2000). Also commonly used are zymosan-induced inflammation animal models as known and described in the art. [00460] The anti-inflammatory activity of the combination therapies of invention can also be assessed by measuring the inhibition of carrageenan-induced paw edema in the rat, using a modification of the method described in Winter C. A. eta!., "Carrageenan-Induced Edema in Hind Paw of the Rat as an Assay for Anti-inflammatory Drugs" Proc. Soc. Exp. Biol Med. 111,544-547, (1962). This assay has been used as a primary in vivo screen for the anti-inflammatory activity of most NSAIDs, and is considered predictive of human efficacy. The anti-inflammatory activity of the test prophylactic ~r therapeutic agents is expressed as the percent inhibition of the increase in hind paw weight of the test group relative to the vehicle dosed control group. [00461] Additionally, animal models for inflammatory bowel disease can also be used to assess the efficacy of the combination therapies ~f invention (Kim et aL, 1992, Scand. J. Gastroentrol. 27:529-537; Strober, 1985, Dig. Dis. Sd. 30(12 Suppl):35-l0S). Ulcerative cholitis and Crohn's disease are human inflammatory bowel diseases that can be induced in animals. Sulfated polysaceharides including, but not limited to amylopeetin, carrageen, amylopectin sulfate, and dextran sulfate or chemical irritants including but not limited to trinitrobeuzenesuiphonic acid (TNBS) and acetic acid can be administered to animals orally to induce inflammatory bowel diseases. [004621 Animal models for autoimmune disorders can also be used to assess the efficacy of the combination therapies of invention. Animal models for autoimmune , thyroid autoimmunity, sytemie lupus eruthematosus, auu glomerulonephritis have been developed (Flanders et al., 1999, Aiaoimmunity 29:235-246; Krogh etal., 1999, J3iochimie 81:511-515; Foster, 1999, Sernin. Nephrol. 19:12-24). [004631 Further, any assays known to those skilled in the art can be used to evaluate the prophylactic and/or therapeutic utility of the combinatorial therapies disclosed herein for autoimmune and/or inflammatory diseases. [00464] Toxicity and efficacy of the prophylactic and/or therapeutic protocols of the instant invention can be determined by standard phaimaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the popi4ation) and the ED50 (the dose therapeutically effective in 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index and it can be expressed as the ratio LDSC/ED~O. Prophylactic and/or therapeutic agents that exhibit large therapeutic indices are preferred. While prophylactic and/or therapeutic agents that exhibit toxic side effects may be used, care should be taken to design a delivery system that targets such agents to the site of affected tissue in order to minimize potential damage to uninfected cells and, thereby, reduce side effects. [00465] The data obtained from the cell culture assays and animal studies can be used in formulating a range of dosage of the prophylactic and/or therapeutic agents for use in humans. The dosage of such agents lies preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage may vary within this range depending upon the dosage form employed and the route of administration utilized. For any agent used in the method of the invention, the therapeutically effective dose can be estimated initially from cell culture assays. A dose may be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i.e., the concentration of the test compound that achieves a half-maximal inhibition of symptoms) as determined in cell culture. Such information can be used to more accurately determine useful doses in humans. Levels in plasma may be measured, for example, by high performance liquid chromatography. [004661 The anti-cancer activity of the therapies used in accordance with the present invention also can be determined by using various experimental animal models for the study of cancer such as the SCID mouse model or transgenic mice or nude mice with human xenografts, animal models, such as hamsters, rabbits, etc. known in the art and described in Relevance of Tumor Models for Anticancer Drug Development (1999, eds. Fiebig and Burger); Coniributions to Oncology (1999, Karger); The Nude Mouse in Oncology Research and Anticancer Drug Development Liulde (1997 ed. Teicher), herein incorporated by reference in their entireties. [004671 Preferred animal models for determining the therapeutic efficacy of the molecules of the invention are mouse xenograft models. Tumor cell lines that can be used as a source for xenografl tumors include but are not limited to, SKBR3 and MCF7 cells, which can be derived from patients with breast adenocarcinoma. These cells have both erbB2 and prolactin receptors. SKBR3 cells have been used routinely in the art as ADCC and xenografl tumor models. Alternatively, OYCAR3 cells derived from a human ovarian adenocarcinoma can be used as a source for xenograft tumors. [00468] The protocols and compositions of the invention are preferably tested in vitro, and then in vivo, for the desired therapeutic or prophylactic activity, prior to use in humans. Therapeutic agents and methods may be screened using cells of a tumor or malignant cell line. Many assays standard in the art can be used to assess such survival and/or growth; for example, cell proliferation can be assayed by measuring 3H-thymidine incorporation, by direct cell count, by detecting changes in transcriptional activity of known genes such as proto-oncogenes (e.g., fos, myc) or cell cycle markers; cell viability can be assessed by trypan blue staining, differentiation can be assessed visually based on changes in morphology, decreased growth and/or colony formation in soft agar or tubular network formation in three-dimensional basement membrane or extracellular matrix preparation, etc. [00469] Compounds for use in therapy can be tested in suitable animal model systems prior to testing in humans, including but n~t limited to in rats, mice, chicken, cows, monkeys, rabbits, hamsters, etc., for example, the animal models described above. The compounds can then be used in the appropriate clinical trials. [00470] Further, any assays known to those skilled in the art can be used to evaluate the prophylactic and/or therapeutic utility of the combinatorial therapies disclosed herein for treatment or prevention of cancer, inflammatory disorder, or autoimmune disease. EXAMPLES [00471] Using a yeast display system, mutant human IgGi heavy chain Fc regions were screened for modified affinity to different Pc receptors. In particular, a mutant Fc library was generated by error prone PCR (Genemorph, Stratagene), and then the mutant Fe proteins were fused to the Aga2p cell wall protein, which allowed the fusion protein to be secreted extraceflularly and displayed on the yeast cell wall. [004721 Soluble forms of the human receptors (FcRJflA and FcRIIB) were cloned. Detection of the IgGi Fc domains on the yeast cell surface, however, is hindered due to the low affinity of FcR for its ligand. In order to circumvent this limitation, soluble FcR tetrameric complexes were formed using an AVITAG sequence which could be enzymatically biotinylated and subsequently reacted with streptavidin conjugated to phycoerythrin (SA-PE; Molecular Probes) to form soluble tetrameric FcR complexes. ELISA assays confirmed that the soluble FcyR tetrameric complexes had a higher avidity for human IgGl relative to the monomeric FcyR. Fc fusion proteins on the yeast cell surface also bound the soluble FcyR tetrameric complexes as assessed by FAGS analysis. [00473] The differential binding of the Fc fusion proteins expressed on the yeast cell surface to soluble teframeric FoyR complexes was monitored by a FACS analysis. Pc fusion proteins with altered affinities for one or more soluble tetrameric FcR complexes were thus identified and were then incorporated into a complete immunoglobulin and expressed in mammalian cells. The mammalian expressed product was used in ELISA assays to confirm the results obtained in the yeast s~irThce display system. Finally, the mutant Fc regions were sequenced to confirm the altered residue(s). 6.1 CLONING, EXPRESSION AND PURIFICATION OF FcRmA MATERIALS AND METHODS [004741 Soluble FcRIIB and Fc'yRIIIA were cloned as follows. The cDNA clones for the human FcyR genes (FcyRUB and FcRTILA) were obtained (gift from Ravetch lab). Soluble region of the FcRIIIA gene (amino acids 7-203) was amplified by PCR (Table 12), digested with BainHI/HindIII and ligated into the pFl2svector (Novagen). This vector was digested with Sall/Notl and a 370 by fragment was gel isolated. The vector hu3A, (gift from 3. Ravetch) was digested with BamIII/S~ll and a 270 by fragment containing the N-terminus of FcRflIA was isolated. Both fragments were coligated into peDNA3. I cut with BamH/NotI to create pcDNA3-FcRflIA (amino acids 1-203). The soluble region of - 180) was amplified by PCR (Table 12), digested with BglII/HindIll and ligated into pET25b(+) (Novagen). This vector was digested with BamI-lI/NotI and a 140 bp fragment was gel isolated. The vector huRlibi (gift from J. Ravetch) was digested with BaniHI/EcoRI and a 440 bp N-terminal FcyRIIB fragment was isolated. Both of these fragments were coligated into pcDNA3.l cut with BamNi/NotI to create pcDNA3-Fc~RJIB (amino acids 1- 180). Recombinant clones were transfected into 29311 cells, supernatants were collected from cell cultures, and soluble recombinant FcyR (rFcyR) proteins were purified on an IgQ sepharose column. RESULTS Recombinant soluble FcyPJJIA (rFcRIIL4) and recombinant soluble FcyRIIB (rFcRIIB) were purified to homogeneity [00475] Subsequent to expression and purification of the recombinant soluble FcR proteins on an IgG sepharose column, the purity and apparent molecular weight of the recombinant purified soluble receptor proteins were determined by SDS-PAGE. As shown in FIG. 3, soluble rFc7RIIIA (FIG. 3, lane 1) had the expected apparent molecular weight of .~35KDa and soluble rFcyRIIB (FIG. 3, lane 4) had the expected apparent molecular weight of—2OKDa. As shown in FIG. 3, soluble rFcyRIIIA migrates as a diffuse "fuzzy" band which has been attributed to the high degree of glycosylation normally found on FcyRJJIA (Jefferis, et al., 1995 Immunol Left. 44, 111-117). 6.1.1 CHARACTERIZATION OF PURI1~1ED RECOMBINANT SOLUBLE FcyRIIIA MATERIALS AND METhODS [00476] Purified soluble rFcyRflIA, which was obtained as described above, was analyzed for direct binding against human monomeric or aggregated IgG using an ELISA assay. The plate is coated with lOng of soluble rFcTRIIIA overnight in lX PBS. Subsequent to coating, the plate is washed three times in lX PBS/O.1% Tween 20. Human IgG, either biotinylated monomeric IgG or biotinylated aggregated IgG, is added to the wells at a concentration ranging from 0.03 mg/mL to 2 mg/mL, and allowed to bind to the soluble rFcRIIIA. The reaction is carried out for one hour at 370C. The plate is washed again three times with iX PBS/0.l% Tween 20. The binding of human IgG to soluble rFcRflIA is detected with streptavidin horseradish peroxidase conjugate by monitoring the absorbance at 6SOnm. The absorbance at 650nm is proportional to the bound aggregated IgG. ~a~jl~ng ELISA experiment, the ability of an FcRIIIA monoclonal antibody, 3G8, a mouse anti-FcRHIA antibody (Pharmingen), to block the binding of the receptor to aggregated lgG is monitored. The washing and incubation conditions were the same as described above, except that prior to IgG addition, a 5-fold molar excess of 3G8 was added and allowed to incubate for 30 minutes at 370C. RESULTS [00478] Purified, recombinant soluble FcyRIll.A binds aggregated lgG specifically [004791 The direct binding of purified recombinant soluble FcyRIHA to aggregated and monomeric IgO was tested using an ELISA assay (FIG. 4). At an IgG concentration of 2µg/mI, strong binding to the aggregated Igo was observed. However, at a similar concentration, no binding was detected to the monomeric IgG. The binding to aggregated IgG was blocked by 308, a mouse anti-FcyRfllA menoclonal antibody that blocks the ligand binding site, indicating that the aggregated IgO binding is via that of the normal FcyRJiIIA ligand binding site (FIG. 4). Soluble rFcRflB was also characterized and shown to bind to IgO with similar characteristics as the soluble rFcyRIllA (data not shown). 6.2 FORMATION OF SOLIJBLE FcyR TETRAMERIC COMPLEXES MATERIALS AND METHODS Construction ofplasmids for expression of soluble FcRIIIA and FeR 711B fused to the AVlTAGpeptide. [00480] To generate soluble FcR tetrameric complexes, the soluble region of the human FcRgIIIA gene (amino acids 7-203) was amplified by POR (Table 12), digested with BamHIfHindIlI and ligated into the pET25b(+) (Novagen). This vector was digested with Sall/Noti, and a 370 bp fragment was isolated by agarose gel electrophoresis. The vector hu3A, (gift from J. Ravetcli) was digested with BaniHi/Sall, and a 270 bp fragment containing the N-terminus of FcRyIIIA was isolated. Both fragments were coligated into pcDNA3. I (Invitrogen), which had been digested with BaniH/Notl to create pcDNA3-FcRgIIIA (amino acids 1-203). [00481] The soluble region of FcR'yllB (amino acids 33- 180) was amplified by PCR (Table I), digested with BglihfHindIII and ligated into pET25b(+) (Novagen). This vector was digested with BainHL'NotI, and a 140 bp fragment was isolated by agarose gel electrophoresis. The vector huRllb1 (gift from 3. Ravetch) was digested with BainHhIEcoRJ, and a 440 by FcRyIIB N-terminal fragment was isolated. Both of these fragments were co-ligated into pcDNA3. 1, which had been digested with BaniHi/NotI to create pcDNA3-FcRJlB (amino acids 1-180). Subsequently, the linker-AVITAG sequence generate the FcyRJflA¬linker-avitag and FcyRIIB- linker-avitag constructs, the pcDNA3. 1 FCRIIIA and FcRJIB constructs were digested with Not I and XbaI (both cut in the vector sequence) and a 86 base pair double stranded oligonucleotide consisting of Noti site at the 5' end and XbaI at the 3' end was ligated into the vector. This 86 bp fragment was generated by annealing two 5' phosphorylated reverse complement oligonucleotides (shown in Table 12 as 5' and 3' linker. avitag primers) with the restrictions sites for Nod and XbaI already pre-designed. Equal volumes of each primer at 100 ng per ul were mixed and the DNA heated to 90 ~C for 15 mInutes and cooled at room temperature for an hour t~ anneal. This created a double-stranded I)NA fragment ready to be ligated to the pcDNA3.l-FcyRIIIA and FcyRflB constructs digested with the respective enzymes. Therefore, the pcDNA3. 1-FcRIJIA-linker-A VITAG and pcDNA3.1-FcRJIB-linker-A Vi TAG, were constructed. TABLE 12: PRIMERS USED FOR CONSTRUCTION OF FcTR AND IgG VECTORS (Table Removed) Biotinylation by BirA [004821 Soluble Fc receptors (FcyR) fused to the 15 amino acid AVITAG sequence (Avidity, 00) (Schatz P.J., 1993, Biotechology, 11:1138-1143) at the C-terminus of the protein cloned into pcDNA3 .1 were generated by transiently transfecting 2931-1 cells using Lipofectamine 2000 reagent (Invitrogen, CA). Supernatants were collected from the cultures and soluble FcR proteins were purified by passing the supematants over an IgG sepharose column. Concentration of the soluble FcR-AVITAG fusion protein was quantitated by absorbance at 280 nm. The AVITAG present on the soluble Fc~R proteins was biotinylated according to the manufacturer's protocol (Avidity, 00) with the E. coil BirA enzyme, a biotin ligase. A 1:100 final dilution of a coclctail of protease inhibitors (Sigma catalog #P8849) and I mg/mi final concentration of Leupeptin (Sigma L-851 1) were added to the mixture to prevent degradation of the proteins. The BirA reaction was incubated at room temperature overnight, following which the solution was concentrated using a Biomax 10K-ultrafiltration device (Millipore) by centrifugation at 3500 rpm at 400. The protein was loaded onto an FPLC Superdex 200 HR 10/30 column (Pharmacia Biotech) in Tris-HOl (20 mM, pH 8.0), 50 mM NaCl to separate the labeled soluble FcR from free biotin. Determination of the extent of biodnylation by streptavidin sh~f I assay [00483] Approximately 80-85% of the protein was biotinylated by the I3irA enzyme (Avidity, CO). The streptavidin-shift assay was used to determine the extent of biotinylation of the protein. Biotinylated protein was incubated with streptavidin (MW 60,000 Daltons) in different ratios. Unbiotinylated protein alone and streptavidin alone are included as controls to determine the extent of biotinylation. The incubation is carried out either on ice for 2 hours or overnight at 400. Samples are analyzed on a 4-12% SDS-PAGE Bis-Tris (Invitrogen, CA) with reducing agent and without boiling of the samples. Streptavidin bound biotinylated protein migrates as a high molecular weight band. The extent of biotinylation is estimated by the amount of monomeric protein left in the sample. Absence of monomeric low molecular weight species and presence of a complex with molecular weight greater than streptavidin alone indicates a high degree of biotinylation. R tetrameric complexes [00484] Formation of FcyR tetrameric complexes was performed according to previously established methodologies for MHC class I tetramers (See Busch, D. H. et al., 1998 immunity 8:353-362; Altman, J. D. et al., 1996, Science 274: 94-96). The concentration of the biotinylated monomeric Fc-yR was calculated based on absorbance at 280 nm. One molecule of streptavidin-phycoerythrin (SA-PE) (Molecular Probes, OR) has the capacity to bind 4 molecules of biotin. A 5:1 molar ratio of monomeric biotinylated Fc'yR to SA-PE (5X monomeric biotinylated FcyR: lX SA-PE) was used to ensure an excess of biotinylated protein. The calculated molecular weight of SA-PE is 300,000 Daltons, therefore 303 mL of a I mg/ni solution of streptavidin-PE has 1 umole of SA-PE, which was added to 5 umole of protein. Efficient formation of tetrameric protein requires SA-PE to be added in step-wise increments. Half the amount of SA-PE was added upfront, and the remaining SA-PE was added in small aliquots every 20-3 0 minutes at 40C in the dark. The intervals for the addition of the remaining SA-PE is flexible. After the addition of SA-PE was complete, the solution was concentrated and loaded over an FPLC size exclusion column as above in phosphate buffered saline, at pH 7.4. The fraction that eluted in the void volume with a molecular weight greater than SA-PE alone was collected. Protease inhibitors were replenished to prevent protein degradation. The solution was concentrated and additional protease inhibitors were added to the final complex for storage. The final concentration of the soluble FcyR tetrameric complex was calculated based on the starting concentration of the biotinylated monomeric protein. For example, ff500 µg of biotinylated protein was used to make the tetrameric complex and the final concentrated tetramers were in a volume of 500 µL, the concentration is estimated to be approximately 1 mg/inL (The losses incurred during concentration are not taken into account as it is di~cu1t to accurately determine how much is lost during each step of the formation of the tetramers. It is also not possible to take an absorbance at 280 urn to measure the concentration due to interference from the PE). Soluble FcR tetrameric complexes were dispensed in small aliquots at ~80oC for long term storage with protease inhibitors. Sodium azide was not added to these preparations as the tetramers were used for screening a yeast display library. On thawing an aliquot, the tetramers were stored at 40C for up to 1 week~ ELISA assay for Characterizing the Tetrameric FcR Complexes [00485] An ELISA was used to characterize the teirameric FoyR complexes. Maxisorb P96 well plate (Nunc) was coated with 25 ng of human IgO in PBS buffer, and incuvated overnight at 4 0C. The plates were washed with PBS/0.5% BSA/0.l% Tween 20 adding the combination of FcyRIIIA tetramers ana rest antibodies to determine blocking with 3G8, a mouse anti-human FcyRIIIA antibody as described below: The blocking step was performed as follows: soluble FcyRIIIA tetramers at a fixed 0.5 mg/mI final concentration were pre-incubated with antibodies for 1 h at room temperature in buffer, PBS/0.5% BSAJO.l% Tween 20. The final concentrations of the antibodies ranged from 60 mg/µL to 0.25 mg/mL. 308 is a mouse anti-human frRflIA antibody, and for the purpose of this experiment, a chimeric version was used, i.e., the variable region of the antibody is a mouse anti-human FcRflIA and the constant region of the heavy and light chains is from the IgOl human region. A chinieric 4.4.20. D265A was also used in this experiment, which is an anti-f luorescein antibody, such that the Fe region contains a mutation at position 265, where an aspartic acid is substituted with alanine in the human IgGI, which results in a reduced binding to FcR This antibody has been characterized prevriously (See Clynes et al., 2000, Nat. Med 6:443-446; Shields et a!., 2001,]. Biol. Chem., 276: 6591-6604). This antibody was used as negative isotype control. [00486] The antibodies were allowed to bind to FcRIIIA tetramers, by pre¬incubation for 1 hour at room temperature. The mixture was then added to the IgG on the washed plate and incubated for and additional hour at room temperature. The plate was washed with buffer and DJl 30c (a mouse anti-human FoyRifiA antibody available from DAKO, Denmark; its epitope is distinct from that of the 308 antibody) at 1:5000 dilution was added and allowed to incubate for 1 hr. at room temperature in order to detect the bound FcRIIIA tetramers. Unbound antibodies were washed out with buffer and the bound DJ13Oc was detected with goat anti-mouse peroxidase (Jackson laboratories). This reagent will not detect the human Fc. After washing out the unbound peroxidase-conjugated antibody, the substrate, TMB reagent (BioFx), was added to detect the extent of blocldng with 308 versus the isotype control and the developed color was read at 650µm. [00487] For direct binding of soluble tetrameric FcRIIIA to IgG by ELISA, maxisorb plates were coated with 25 ng IgG as described above. The soluble tetrameric FcRIILA were added from 20 mg/mL to 0.1 mg/niL and the biotinylated monomeric soluble tetrameric FoyRIIIA were added at concentrations ranging from 20 mg/µL to 0.16 mg/µL. Detection was the same as above with DJI3Oc, followed by goat anti-mouse-peroxidase antibody. Color developed with the TMB reagent and the plate was read at 650 nm. Soluble FcyRIIL4 tetrameric complex binds monomeric human IgO via its normal ligand binding site 1004881 Soluble FcyRIIIA-AVITAG fusion proteins were generated, isolated, and analyzed as described in the Material and Methods section using an ELISA assay and were shown to have similar properties as the non-AVITAG soluble FoyRIHA protein (data not shown). The fusion proteins were biotinylated, and the tetrameric complexes were generated as described above. 1004891 The soluble FcR tetrameric complex was then assessed for binding its ligand, monomeric human IgO, using an ELISA assay. Analysis by ELISA showed the soluble tetrameric FoyR complexes bind monomeric human IgO specifically. As shown in FIG. 5A, binding of soluble tetrameric FcyRflIA to monomeric human IgO is blocked by 3G8, a mouse anti-human FeylliA monoclonal antibody, as monitored by the absorbance at 650nm. On the other hand, the 4-4-20 monoclonal antibody harboring the D265A mutation was not able to block the binding of soluble tetraineric FcRIIIA to monomeric human IgG (FIG. 5A). This experiment thus confirms that binding of the soluble tetrameric FcRflIA complex occurs through the native ligand binding site. Soluble FcVPJIIA tetrameric complex binds monomeric human lgG with a greater avidity than monomeric soluble Fe yR lilA (00490] The direct binding of soluble tetrameric FcRJIIA to aggregated human IgG was assessed using an ELISA assay and compared to the direct binding of soluble monomeric FcRflIA to monometic human IgG. As shown in FIG. SB, soluble tetrameric FcRflIA binds human IgG with a higher avidity (8-10 fold) than the soluble monomeric receptor, as monitored by the absorbance at 450 Din. [00491] The binding of soluble FcRflIA tetraineiic complex was also assayed using magnetic beads coated with Fc Fragment purified from IgGi (FIG. 5). Soluble FoyRflIA tetramerie complex binds to the IgGl Fe-coated beads, under conditions in which monomer binding is not detected. Specificity of binding was shown by pre-incubating the receptor complex, with an anti-FcyRmA monoclonal antibody, LNK1 6, which blocks Fc binding. This assay further confirms that soluble FcRIIIA tetrameric complex binds monomeric IgG through its normal ligand binding site, and the avidity of the receptor is increased due to multiple binding sites within the complex. 6.3 CONSTRUCTION OF YEAST STRAIN FOR DISPLAY OF MUTANT IgGi Pc DOMAINS METHODS [00492] The pYDl vector (Invitrogen) is derived directly from a yeast replicating vector, pCT3O2 (Shusta, etal., 2000 Nat. Biotechnol. 18: 754-759, that has been successfully used to display T-cell receptors and a number of scFVs. This plasmid is centromeric and harbors the TRP1 gene enabling a relatively constant copy number of 1-2 plasmids per cell in a trpl yeast strain. Directional cloning into the polylinker places the gene of interest under the control of the GALl promoter and in-frame with AGA2. Fusion of the IgG Fc domain to the yeast Aga2p results in the extracellular secretion of the Aga2-Fc fusion protein and subsequent display of the Fe protein on the cell wall via disulfide bonding to the yeast Aga 1p protein, which is an integral cell wall protein. [00493] In order to optimize the display levels, different fragments from the IgGl heavy chain were amplified by PCR and cloned into pYDi. Specifically, the Fc region of the IgGl heavy chain (allotype IGlm(a); amino acids 206- 447) was amplified by POR (Table 1) from the IMAGE clone 182740, digested with EcoRI/Sall and ligated into the pYDl vector (Invitrogen). The initial clone from IMAGE contained a deletion of a single nucleotide at position 319 which was corrected by in vitro site directed mutagenesis to construct pYD-G1F206 (Quickehange, Stratagene). (00494] The CHl-CH3 fragment (amino acids 118-447) was amplified from the heavy chain clone of the MAb B6.2 in the pCINEO vector using a 5' oligo (mcrO2S;chl(f)) and a 3' oligo (11021) (See Table 8). The fragment was digested with Baniflh/NotI and ligated into the pYDl vector to construct pYD-CHl. [00495] FIG. 7, shows a schematic presentation of the constructs. The CH1-CH3 construct contains the CHi domain In addition to the hinge-CH2-CH3 domains of the heavy chain, G1F206 contains 6 amino acid residues upstream of the hinge and (11F227 starts within the hinge region at an endogenous proteolytic cleavage site (Jendeberg eta!., 1997J. Immunol. Meth. 201:25-34). 6.4 IMMUNOLOCALIZATION AND CHARACTERIZATION OF Fe DOMAINS ON THE YEAST CELL WALL MATERIALS AND METHODS [00496] Constructs containing the Aga2p-Fc fusion proteins and a control vector, pYDI, lacking any insert, were transfonned into the yeast strain EBY100 (Invitrogen), MATa ura3-52 trpl leu2Al his3A200pep4::HIS3prblAl.6R can) GAL::GAL-A GAl, using a standard lithium acetate yeast transformation protocol (Gietz et aL, 1992 NucleIc Acids Res. 20:1425) Subsequently, tryptophan prototrophs were selected on defined media. cell populations and induction of Agalp and the Aga2p-Fc fusion proteins were accomplished by growth in glucose, followed by growth in media containing galactose as the primary carbor~ source for 24-48 hrs at 200C. Growth in galactose induces expression of the Aga2-Fc fusion proteins via the GALl promoter, which subsequently leads to the display of the Fc fusion proteins on the yeast cell surface. RESULTS FACS Analysis of Fc Fusion Proteins [004971 Expression of Fc fusion proteins on the yeast cell surface was analyzed by iinmunostaining using a PE-conjugated polyclonal F(ab)2 goat anti-human FcR and HP6017 (Sigma) antibody (Jackson Inimununoresearch Laboratories, Inc.). Fluorescence microscopy shows peripheral staining for the tbree Fe fusion proteins. The control strain, harboring vector alone, shows little or no staining (data not shown). FACS analysis was used to quantitate the staining (FIG. 8). The yeast strain containing the CHI-CH3 fusion demonstrated the highest percentage of cells stained with both antibodies (FIG. 8B and F). The G1F227 construct showed the greatest mean fluorescence intensity (FIG. 8, panels C and G). Characterization of the Binding of Fc Fusion Proteins Expressed on the Yeast cell Surface [004981 The natural context of the Fc and FcR proteins places the receptor on the cell surface and the Fc as the soluble ligand; however, the yeast Fc surface display reverses the geometry of the natural interaction. Detection of the IgOl Fc proteins on the surface of the yeast cell wall is complicated by both the low affinity of the FcR for its ligand and the reverse geometry inherent in the display system. Although the latter point cannot be altered, the avidity of the ligand was improved as explained above by forming soluble FcR tetrameric complexes, which allows detection of FcR binding to the Fe fusion proteins expressed on the surface yeast cell wall. [00499] To characterize the binding of soluble tetrameric FcR complexes to the surface displayed Fc fusion proteins, yeast cells expressing different Fe constructs were incubated with the soluble rFcRIIIA tetrameric complex and analyzed by FACS. Yeast cells harboring pYD-CHl, displaying the wild type CHl-CH3 construct were bound by the soluble rFcyRIIIA tetrameric complex as shown by FACS analysis. The G1F206 and G1F227 strains, however, showed little or no binding to the soluble rFcyRTIIA tetrameric complex as shown by FAGS analysis (data not shown). the Fe region that block binding to the FcRs have been identified (Shields eta?., 2001; JBiol.Chem. 276: 6591-6604). One of these mutations, D265A, was incorporated into pYD-CHl and this mutant was expressed on the yeast cell surface. These cells were incubated with the soluble FcyRIIIA tetrameric complex using a high concentration of ligand (0.15 mM of Fc; 7.5 mM of D265A) FAGS analysis indicated that soluble FcRIIIA tetrameric complex bound to wild type Pc (FIG. 9A) but soluble FcRIIIA tetrameric complex did not bind to the D265A-Fc mutant indicating that FcR is interacting with the normal FcR binding site in the lower hinge-CH2 region (FIG. 9B). [00501] Antibodies against the Fc2'RJIIA ligand binding site blocked binding of the soluble FcyRIIIA tetrameric complex to the wild type Fc protein displayed on the yeast cell surface wall, as analyzed by FACS (FIG. 10). The binding of soluble FcRIIIA tetrameric complex was blocked by the 3G8 antibody, as well as the LNK16 antibody, another anti¬FcRIJIA monoclonal antibody (Advanced Immunological) (Tam eta!., 1996 J Immunol. 157:, 1576-1581) and was not blocked by an irrelevant isotype control. Therefore, binding of soluble FcyRIIIA tetrameric complex to the Fc proteins displayed on the yeast cell surface occurs through the normal ligand binding site. The limited binding of the FcRflIA tetrarneric complex indicates that a subpopullation of cells have a correctly folded Fe that is accessible to FcR. There are numerous reasons why only a subpopulation of cells may be able to bind the ligand, for example, they may be at different stages of cell cycle or the fusion proteins may not have been exported. [00502] In order to determine the dissociation constant of the FcyRIIIA-tetramer binding to the Fc fusion proteins on the yeast cell surface, the binding of a range of FoyRflIA tetrameric complex was analyzed using FACS. FcRIIIA tetrameric complex was titrated at concentrations of 1.4 p.M to 0.0006 pM. Using the mean fluorescence intensity as a measure of binding affinity and nonlinear regression analysis, the 1% was determined to be 0.006 pM (+1- 0.001) (data not shown). 6.5 CONSTRUCTION OF Fc MUTANT LIBRARY [00503] A mutant Fc library was constructed using primers flanking the Fe fragment in the Fc-CHl construct and error-prone POR (Genemorph, Stratagene). The CHl-CH3 insert in vector pYD-CHI was amplified using a mutagenic PCR (Genemoiph, Stratagene). Five reactions were carried out using the pYD-upstream and pYD-downstream primers (Invitrogen). The resultant amplified fragment was digested with XHOIIBainHI and ligated into pYDi. The ligation reaction was then transformed into XLIO ultracompetent cells 1 x 106 transfonnants, with 80% of the transtormants containing inserts. [00504J Sequence analysis of 28 random plasmids from the library indicated a mutation frequency —2-3 mutations/kb with a breakdown of 40% conserved nucleotide changes and 60% of the mutations resulting in amino acid changes. [005051 The library was transformed into the yeast strain BBYlOO, MATa ura3 -52 trp I leu2Al his3A200pep4:.HlS3prblAL6R can 1 GAL GAL-A GA J::URA3 to a high efficiency, —3.3 x105 transfonnants/ug, in 30 independent transformation reactions to create a total of —1 ~ yeast transformants (Gietz, et aL, 1992, Nucleic Acids Res. 20: 1425'). The library was pooled and amplified by growth in glucose. 6.6 SELECTION M~11) ANALYSIS OF Fc MUTANTS MATERIALS AND METHODS ELISA assay for screening Fe mutants [00506] ELISA plates (Nunc F96 MaxiSorp Irumunoplate) were coated with 50 mi/well of 0.5 mg/µl BSA-FITC in carbonate buffer at 40C, and allowed to incubate overnight. Plates were washed with lX PB Sb. I %Tween 20 (PBST) 3 times. 200 mi/well of PBST/0.5%BSA was added and the plates were incubated for 30 mins at room temperature. Plates were washed three additional times with PB ST. 50 mI/well of 1:4 diluted 4-4-20 antibody (approximately 3 mg/mL which would lead to a final concentration of 0.7-0.8 mg/well) either wild type or containing an Fe mutant, was added from conditional medium in PBST/0.5%BSA and allowed to incubate for 2 hrs at room temperature. Plates were washed with PBST three times. Purified, biotinylated monomeric FcRiIIA at 3 mgfrnl (in PBST/0.5%BSA) was added (50 p.1/well) to the plates and allowed to incubate for 1.5 hours at room temperature. Plates were washed with PBST three times. 50 mI/well of a 1:5000 dilution of Streptavidin-HRP(Pharmacia, RPN 123v) in PBST/0.5%BSA was added and the plates were incubated for 30 minutes at room temperature. Plates were washed with PBST three times. 80 mi/well of TMB reagent (BioFX) was then added to the plates, and allowed to incubate for 10-15 minutes at room temperature in a dark place. The reactions were finally stopped by adding 40 nil/well of stop solution (0.18 M sulfuric acid). Plates were then monitored for absorbance at 450 am. After the first screen, the interesting candidates were further confirmed by serial titration of 4-4-20-Fc mutants in the inimuno-complex based binding ELISA. A few modifications were made in this ELISA. For coating the plates, 2 mg/nil BSA-FITC was used. Based on IgG quantitation results, wikldMPe or mutants) from conditional medium was added to a final -concentration of 1,0.5,0.25, 0.125, 0.063, and 0mg/mi in PBST-/0.5% BSA. FACS Screen for the Cell Surface displayed Fc proteins [00507] Cells were grown in at least 10 mIs of HSM-Txp-Ura pH 5.5 with glucose for 16-24 hrs or until 0D600 was greater than 2.0. Cells were spun down at —2000 rpm for 5 minutes. Cells were resuspended in an equal volume of HSM-Trp-Ura, pH 7.0 with gal actose. In a 125 ml flask, 36 mIs of galactose media was added, and inoculated with 9 mis of culture, which was incubated at 200C with shaking for 24-48 hrs. Growth was monitored by measuring 0D600 at 8-16 hr intervals. Cells were harvested at 2K rpm for 5 minutes, and resuspended in an equal volume of 1XPBS, pH 7.4. [00508] Equilibrium screen: An appropriate amount of cells was incubated while maintaining an excesss of ligand. For example, it is preferred to start with a number of cells needed to ensure 10-fold coverage of the library. For the first sort with a library containing I ~ transformants, 1 ~ cells should be used. In fact it is best to start with 1 ~ cells to compensate for loss during the staining protocol. 100509] Incubation was typically done in a 1.5 niL tube in volumes of 20-100 mis for 1 hour at 40C in the dark on a rotator (incubation buffer: 1XPBS pH7.4; 1 mg/nil BSA). Cells were washed once in 500 ml of incubation buffer and spun down at 4K rpm for 2.5 minutes. Cells were resuspended in 100 ml incubation buffer and incubated with the second staining reagent. For Fc-CHl, a F(ab)~ goat anti-hFc F(ab)2-FITC antibody (Jackson lmmunoresearch Laboratories, Inc.) can be used to stain for CHI expression. Staining was done with I niL for 30 minutes. Cells were washed additionally in 500 rnL of incubation buffer and spun down at 4K rpm for 2.5 minutes, resuspended in I mL IX PBS 1 mg/niL BSA and analyzed by FAGS. [00510] Typical equilibrium screen sort gates and number of cells collected are shown in Table 13. TABLE 13. SORT GATES AND NUMBER OF CELLS SORTED (Table Removed) and 4th sorts, cells were plated directly on -trp-ura plates to identify individual mutants. This typically recovered —200-400 colonies per plate. After collection the cells were placed in 10 mLs of glucose media in a 50 nit conical tube and grown at 3000. The whole procedure was repeated iteratively. RESULTS FACS analysis of Fc Mutants [005121 After induction in galactose media, cells were harvested and co-stained with soluble FoyRilIA tetrameric complex-PB labeled and F(ab2) of mouse anti-human Fe-FITO labeled (Jackson Immi.moresearch Laboratories, Inc.). Cells were analyzed by FACS and sort gates were used to select the cells that showed the highest affinity for the soluble FcRIHA tetrameric complex relative to the amount of Fe expression on the cell surface (FIG. 11). For example, a cell containing a mutant Fe that binds better to the soluble FcyRIIIA tetrameric complex may express fewer Fe fusion proteins on the yeast cell surface, and this cell will be in the lower left hand corner of the sort gate. [00513] Four consecutive sorts were done to enrich for those mutants that showed the highest affinity for the soluble FcyRIHA tetrameric complex. The gates for each successive sort were 5.5%, 1%, 0.2% and 0.1%. After the last sort, cells were plated onto selective media and individual colonies were isolated. Each individual colony represented a clonal population of cells harboring a single Fc mutant within the Aga2-Fc fusion protein. Initially 32 independent colonies were picked and tested by FAGS for binding to soluble FcyRIIIA tetrameric complex (FIG. 12). Eighteen mutants showed an increase in binding intensity as measured by the percentage of cells bound by soluble PcyRfllA tetrameric complex and the mean fluorescence intensity of the bound cells. [005141 Mutations showing an increase in binding to FcyRflIA were also tested for binding to soluble FcRIIB tetrameric complex (FIG. 12). Most mutations that lead to an increase in binding to the soluble FcyRIIIA tetrameric complex also resulted in detection of FcyRIIB tetrameric complex staining (FIG. 12). Based on both previous physical and genetic data, some mutations that increase binding to FcyRIIIA, are expected to also increase binding to FcyRflB (Shields eta!., 2001, JEloiChem. 276: 6591-6604; Sondermaun eta!., 2000, Nature 406:267-273). Analysis of mutants in a 44-20 MAb produced in a human cell line. [00515] Isolation and analysis of mutations in the yeast system allows for fast identification of novel mutant alleles. The use of a heterologous system to isolate mutations could result in the identification of mutations that enhazice binding through an alteration that -z~uis~l4ipg~,~lteration in glycosylation that is specific to yeast. lo anaiyze me re mutations in an immunoglobulin molecule that is produced in human cells, the mutants were subcloned into a maninialian expression vector, containing the heavy chain of the anti-fluorescein monoclonal antibody, 4-4-20 (Kranz et al., 1982 J.Biol.Chem, 257(12): 6987-6995). The mutant 4-4-20 heavy chains were transiently coexpressed with the light chain clones in the human kidney cell line (293H). Supernatants were collected and analyzed by ELISA (FIG. 13). [00516] Aceording to the ELISA assay, the majority of the mutants that were identified as having an enhanced affinity for the soluble monomeric Fe~yRIIIA complex, in the secondary FACS analysis, also showed an increase in binding to the soluble FcyRflIA tetrameric complex when present in the Fe region of the 44-20 monoclonal antibody produced in the human cell line (FIG. 1 3A). Two mutants, number 16 and number 19, however, showed a decrease in binding to the soluble Fc'yRJIIA monomeric complex. [00517] Table 14, summarizes the mutations that have been identified and their correponding binding characteristics to FcyRflIA and Fc'yRIIB, as determined by both yeast display based assays and ELISA. In Table 14, the symbols represent the following:• corresponds to a 1-fold increase in affinity; + corresponds to a 50% increase in affinity; -corresponds to a 1-fold decrease in affinity; —~ corresponds to no change in affinity compared to a comparable molecule comprising a wild-type Fc region. TABLE 14: MUTATIONS IDENTIFIED AND BINDING CHARACTERISTICS (Table Removed) [00518] Analysis of soluble FcR]IB tetrameric complex binding shows that 7 out of the 8 mutants that showed an increase in binding to the soluble FcRflIA tetrameric complex also had an increased binding to the soluble FcRIIB tetrameric complex (FIG. 13B). One mutant, number 8, showed a decrease in binding to the soluble FcRJIB tetrameric complex. Three of the mutants show no difference in binding to either the soluble FcyRIIIA tetrameric complex or the soluble FcRUB tetrameric complex, possibly due to mutations that result in yeast specific alterations. 6.7 ADCC ASSAY OF Fc MUTANTS [00519] Effector cell preparation. Peripheral blood mononuclear cells (PBMC) were purified by Ficoll-Paque (Pharmacia, 17-1440-02) Ficoll-Paque density gradient centrifugation from normal peripheral human blood (Biowhittaker/Poietics, 1W-406). Blood was shipped the same day at ambient temperature, and diluted 1:1 in PBS and glucose (lg/lL) and layered onto Ficoll in 15 niL conical tubes (3 niL Ficoll; 4 niL PBS/blood) or 5OmL conical tubes (l5mL: Ficoll; 2OmL PBS/blood). Centrifugation was done at 1500 rpm (400 ret) for 40 minutes at room temperature. The PBMC layer was removed (approximately 4-6 niL from 50 niL conical tube) and diluted 1:10 in PBS (which contains no Ca2~ or Mg24) in a 50 mL conical tube, and spun for an additional ten minutes at 1200 rpm (250 rcf) at room temperature. The supematant was removed and the pellets were resuspended in 10-12 niL PBS (which contains no Ca2~orMg~4),transferredto 15 niL conical tubes, and spun for another 10 minutes at 1200 rpm at room temperature. The supernatant was removed and the pellets were resuspended in a minimum volume (1-2 µL) of media (Isocove's media (IMDM) + 10% fetal bovine serum (PBS), 4 mM GIn, Penicillin/Streptomycin (P/S)). The resuspended PBMC were diluted to the appropriate volume for the ADCC assay; two fold dilutions were done in an ELISA 96 well plate (Nunc The yield of PBMC was approximately 3-5x10' cells per 40- 50 znL of whole blood. [00520] Target cell preparation: Target cells used in the assay were SK-BR-3 (ATCC Accession number HTB-30; Trempe et al., 1976, Cancer Res. 33-41), Raji (ATCC Accession number CCL-86; Epstein Ct al., 1965, .1 Nail. Cancer Inst. 34: 231-40), or Daudi cells (ATCC Accession number CCL-213; Klein et al., 1968, Cancer Res. 28: 1300-10) (resuspended in 0.5 ruL IMDM media) and they were labeled with europium chelate bis(acetoxymethyl) 2,2":6',2" terpyiidine 6,6' dicarboxylate (BATDA reagent; Perkin Elmer DELFIA reagent; C136-l00). K562 cells (ATCC Accession number CCL-243) were used as control cells for NK activity. The Daudi and Raji cells were spun down; the SK¬BR-3 cells were trypsinized for 2-5 minutes at 370C, 5% CO2 and the media was neutralized prior to being spun down at 200-350 G. The number of target cells used in the assays was about 4-5x106 cells and it did not exceed 5xlO since labeling efficiency was best with as few as 2x106 cells. Once the cells were spun down, the media was aspirated to 0.5 mL in 15 mL Falcon tubes. 2.5 tl of BATDA reagent was added and the mixture was incubated at 370C, 5% CO2 for 30 minutes. Cells were washed twice in l0mL PBS and 0.125 mM sulfinpyrazole ("SP"; SIGMA 5-9509); and twice in 10 niL assay media (cell media + 0.125 mM sulfinpyrazole). Cells were resuspended in 1 mL assay media, counted and diluted. [00521] When SK-BR-3 cells were used as target cells after the first PBSISP wash, the PBS/SP was aspirated and 500 µg/mL of FITC was added (PIERCE 461110) in IIvIDM media containing SP, GIn, and P/S and incubated for 30 minutes at 370C, 5% CO2. Cells were washed twice with assay media; resuspended in I niL assay media, counted and diluted. [00522] Antibody Opsonization: Once target cells were prepared as described supra, they were opsonized with the appropriate antibodies. In the case of Fe variants, 50 p1, of 1x105 cells/niL were added to 2x concentration of the antibody harboring the Fe variant. Final concentrations were as follows: Ch-4-4-20 final concentration was 0.5-1 µg/mL; and Ch4D5 final concentration was 30 ng/mL-l ng/mL. [00523] Opsonized target cells were added to eff'ector cells to produce an effector:target ratio of 75:1 in the case of the 4-4-20 antibodies with Fe variants. In the case of the Ch4D5 antibodies with Fe variants, effector: target ratio of 50:1 or 75:1 were achieved. Effective PBMC gradient for the assay ranges from 100:1 to 1:1. Spontaneous release (SR) was measured by adding 100 pL of assay media to the cells; maximal release (MR) was measured by adding 4% TX-l00. Cells were spun down at 200 rpmin a Beckman centrifuge for 1 minute at room temperature at 57 G. Cells were incubated for 3- After incubation, the cells were spun at lOOOipm in a Beckman centrifuge (about 220xg) for five minutes at 100C. 20 j.d of supematant was collected; 200p.L of Eu solution was added and the mixture was shaken for 15 minutes at room temperature at 120 rpm on a rotary shaker. The fluorescence was quantitated in a time resolved fluormeter (Victor 1420, Perkin Elmer) RESULTS [00524] As described above, the variant Fe regions were subeloned into a mammalian expression vector, containing the heavy chain of the anti-fluoresceine monoclonal antibody, 4-4-20 (Kranz et al., 1982 J.Biol.Chem, 257(12): 6981-6995). The variant 4-4-20 heavy chains were transiently coexpressed with the llght chain clones in the human kidney cell line (293H). Supernatants were collected and analyzed using the ADCC assay. FIG. 14 shows that ADCC activity of the mutants is concentration-dependent. As sunimarized in Table 8, five irnmuno globulins with variant Fe regions had an enhanced ADCC activity relative to wild type ch 4-4-20. The five mutants were as follows: MGFc-27 (G3 16D, A378Y, D399E); MGFc-3 1 (P247L, N421K); MGFc-l0 (K288N, A3305, P396L); MGFc¬28 (N3 151, V379M, T394M); MGFc-29 (P2431, V379L, G420V). [00525] Additonal 4-4-20 immunoglobulins with variant Fc regions were assayed for their ADCC activity relative to a 4-4-20 inimunoglobulin with a wild-type Fe region. These results are summarized in Table 15. [00526] ADCC assays were also carried out using the same protocol as previously described for the 4-4-20 antibody, however, the variant Fc regions were cloned into a humanized antibody (Ab4D5) which is specific for the human epidermal growth factor receptor 2 (HER2/neu). In this case, SK-BR-3 cells were used as the target cells that were opsonized with a HER2/neu antibody carrying a variant Fe region. HER2/neu is endogenously epxressed by the SK-BR-3 cells and therefore present on the surface these cells. FIG. 15 shows the ADCC activity of RER2/neu antibodies carrying variant Pc regions. Table 16 summarizes the results of ADOC activity of the mutants in the context of the HER2/neu antibody. Nomialization was carried out by comparing the concentration of the mutant to the wildtype antibody required for a specific value of percent cell lysis. [00527] As shown in FIG. 154, MGFc-5 (V379M), MGFc-9 (P2431, V379L), MOFe-lO (K288N, A3305, P396L), MGFc-13 (K334E, T359N, T3665), and MGFc-27 (03 16D, A378V, D399E) mutants that were cloned in to the humanized anti-HER2/neu antibody exhibited a higher % specific lysis of SK-BR-3 cells relative to the wild antibody. Table 15. SUMMARY OF ADCC ACTIVITY OF MUTANTS (Table Removed) Table 16: SUMMARY OF MUTANTS (Table Removed) OF KINETIC PARAMETERS OF Fc MUTANTS [00528] Kinetic parameters of the binding of ch4-4-20 antibodies harboring Fc mutants to FcyRJIIA and FcyRIIB were analyzed using a BlAcore assay (BlAcore instrument 1000, BlAcore Inc., Piscataway, N.J.). The FcyRIIIA used in this assay was a soluble monomeric protein, the extracellular region of FOTRIIIA joined to the linker¬AVITAG sequence as described in Section 6.2 supra. The FcyRIIB used in this assay was a soluble dimeric protein prepared in accordance with the methodology described in U.S. Provisional Application No. 60/43 9,709 filed on January 13, 2003, which is incorporated herein by reference. Briefly, the FcyRflB used was the extracellular domain of FcTRIIB fused to the hinge-CH2-CH3 domain of human IgG2. [005291 BSA-FITC (36 jig/inL in 10mM Acetate Buffer at pH 5.0) was immobilized on one of the four flow cells (flow cell 2) of a sensor chip surface through amine coupling chemistry (by modification of carboxymethyl groups with mixture of NHS/EDC) such that about 5000 response units (RU) of BSA-FITC was immobilized on the surface. Following this, the unreacted active esters were "capped off" with an injection of lM Et-N112. Once a suitable surface was prepared, ch 4-4-20 antibodies carrying the Fc mutations were passed over the surface by one minute injections of a 20 jig/mL solution at a 5 jiL/mL flow rate. The level of ch-4-4-20 antibodies bound to the surface ranged between 400 and 700 RU. Next, dilution series of the receptor (FcyRIIIA and FcyRflB-Fc fusion protein) in HBS-P buffer (10mM HEPES, 150 mM NaCi, .005% Surfactant P20, 3mM EDTA, pH 7.4) were injected onto the surface at 100 jiL/min Antibody regeneration between different receptor dilutions was carried out by single 5 second injections of 100mM NaHCO3 pH 9.4; 3M NaCl. [00530] The same dilutions of the receptor were also injected over a BSA-FITC surface without any ch-4-4-20 antibody at the beginning and at the end of the assay as reference injections. [00531] Once an entire data set was collected, the resulting binding curves were globally fitted using computer algorithms supplied by the manufacturer, BlAcore, Inc. (Piscataway, NJ). These algorithms calculate both the Kno and K~ from which the apparent equilibrium binding constant1 K1, is deduced as the ratio of the two rate constants (Le., More detailed treatments of how the individual rate constants are derived can be found in the BlAevaluaion Software Handbook (BLAcore, Inc., Piscataway, NJ). [005321 Binding curves for two different concentrations (200 uM and 800 nM for FoyRILLA and 200 nM and 400aM for FcyRflB fusion protein) were aligned and responses of captured antibodies, and the reference curves were subtracted from tue expenmental curves. Association and dissociation phases were fitted separately. Dissociation rate constant was obtained for interval 32-34 sec of the dissociation phase; association phase fit was obtained by a 1:1 Langmuir model and base fit was selected on the basis Rm~ and chi2 criteria. RESULTS [00533] FIG. 16 shows the capture of ch 4-4-20 antibodies with mutant Fc regions on the BSA-FTIC-immobilized sensor chip. 6µL of antibodies at a concentration of about 20µg/mL were injected at 5 pL/min over the BSA-FITC surface. FIG. 17 is a sensogram of real time binding of FcRIIIA to ch-4-4-20 antibodies carrying variant Fc regions. Binding of FcyRIIIA was analyzed at 200 nM concentration and resonance signal responses were normalized at the level of the response obtained for the wild type ch-4-4-20 antibody. Kinetic parameters for the binding of FcyRIIIA to ch-4-4-20 antibodies were obtained by fitting the data obtained at two different FcyRIIIA concentrations, 200 and 800 uM (FIG. 18). The solid line represents the association fit which was obtained based on the K- values calculated for the dissociation curves in interval 32-34 seconds. Kr, and K~ represent the average calculated from the two different FcRLILA concentrations used. FIG. 19 is a sensogram of real time binding of FcyRIIB-Fc fusion protein to ch-4-4-20 antibodies carrying variant Fc regions. Binding of FcyRIIB-Fc fusion protein was analyzed at 200 nM concentration and resonance signal responses were normalized at the level of the response obtained for the wild type ch-4-4-20 antibody. Kinetic parameters for the binding of FcRIIB-Fc fusion protein to ch-4-4-20 antibodies were obtained by fitting the data obtained at two different FcyRIIB-Fc fusion protein concentrations, 200 and 800 nM (FIG. 20). The solid line represents the association fit which was obtained based on the - calculated for the dissociation curves in interval 32-34 seconds. Kr, and K()rr represent the average from the two different FcRIIB-Fc fusion protein concentrations used . [00534] The kinetic parameters (K- and ICon) that were determined from the BlAcore analysis correlated with the binding characteristic of the mutants as determined by an ELISA assay and the functional activity of the mutants as determined in an ADCC assay. Specifically, as seen in Table 17, mutants that had an enhanced ADCC activity relative to the wild-type protein, and had an enhanced binding to FcRflIA as determined by an EUSA assay had an improved K- for FcRHIA (i.e., a lower Kon). Therefore, a lower ICotr value a mwtault Fe protein relative to a wild type protein may niceiy to nave an enhanced ADCC function. On the other hand, as seen in Table 18, mutants that had an enhanced ADCC activity relative to the wild-type protein, and had a reduced binding for Fc'yRIIB-Fc fusion protein as determined by an ELISA assay had a higher K0ff for FcyRIIB -Fe fusion protein. [00535] Thus, the K(,ff values for FcRIIIA and FcRIIB can be used as predictive measures of how a mutant will behave in a functional assay such as an ADCC assay. In fact, ratios of K0ff values for FcyRIIIA and FcRIIB-Fc fusion protein of the mutants to the wild type protein were plotted against ADCC data (FIG 21). Specifically, in the case of K0ff values for FcRilIA, the ratio of Koff (wt)/ K0ff (mutant) was plotted against the ADOC data; and in the case of K0ff values for FcRIIB, the ratio of ICon (mut)/ ICon (wt) was plotted against the ADCC data. Numbers higher than one (1) show a decreased dissociation rate for FcRIIIA and an increased dissociation rate for FcRUB -Fe relative to wild type. Mutants that fall within the indicated box have a lower off rate for FcRHIA binding and a higher off-rate for FcRLIB -Fe binding, and possess an enhanced ADCC function. Table 17. Kinetic parameters of FeRlila binding to ch4-4-2OAb obtained by "separate fit" of 200nM and 800nM binding curves (Table Removed) fit to the group by ELISA or ADCC data. Table 1. Kinetic parameters of FcRIIB-Fc binding to wild type and mutant ch4-4-2Oab obtained by “separate fit” of 200 nM and 800 nM binding curves. (Table Removed) 6.9 SCREENING FOR Fe MUTANTS USING MULTIPLE ROUNDS OF ENRICHMENT USING A SOLID PHASE ASSAY [00536] The following mutant screens were aimed at identifying additional sets of mutants that show improved binding to FcRIIIA and reduced binding to FcRIIB. Secondary screening of selected Fe variants was performed by ELISA followed by testing for ADCC in the 4-4-20 system. Mutants were than selected primarily based on their ability to mediate ADCC via 4-4-20 using Fluorescein coated SK-BR3 cells as targets and isolated PBMC from human donors as the effector cell population. Fc mutants that showed a relative increase in ADCC, e.g., an enhancedment by a factor of 2 were than cloned into anti-HER2/neu or anti-CD2O chAbs and tested in an ADCC assay using the appropriate tumor cells as targets. The mutants were also analyzed by BlAcore and their relative ICon were determined. [00537] Screen 1: Sequential solid phase depletion and selection using Magnetic beads coated with Fc,.IU.IB followed by selection with magnetic beads coated with FcrPJIIA. The aim of this screen was identification of Fc mutants that either no longer bind show iesl binding to FcRflB. A 10-fold excess of the naYve library (—10' cells) was incubated with magnetic beads ("My One", Dynal) coated with FcyRIIB. Yeast bound to beads were separated from the non-bound fraction by placing the tube containing the mixture in a magnetic field. Those yeast cells that were not bound to the beads were removed and placed in fresh media. They were next bound to beads that were coated with FcRIIIA. Yeast bound to beads were separated from the nonbound fraction by placing the tube containing the mixture in a magnetic field. Nonbound yeast were removed and the bound cells were removed by vigorous vortexing. The recovered cells were regrown in glucose containing media and reinduced in selective media containing galactose. The selection process was repeated. The final culture was than used to harvest DNA. Inserts containing the Fe domain were amplified by PCR and cloned into 4-4-20. Approximately 90 Fc mutants were screened by 4-4-20 ELISA and ADCC assays and the resultant positive mutants are shown in Table 19. Table 19: Mutants selected by sequential solid phase depletion and selection using Magnetic beads coated with FcRJIB followed by selection with magnetic beads coated with Fc'yRIIIA. (Table Removed) [00538] Screens 2&3: Mutants Selected by FACS, Equilibrium and Kinetic Screening: The first library screen identified a mutation at position 396, changing the amino acid from Proline to Leucine (P396L). This Fe variant showed increased binding to both FcRiIIA and FcRJJB. A second library was constructed using P396L as a base line. PCR mutagenesis was used to generate —l0- mutants each of which contained the P396L mutation and contained additional nucleotide changes. The P396L library was screened using two sets of conditions. [00539] An equilibrium screen was performed using biotinylated FcyRflIA -linker¬avitag as a monomer, using methods already described. Approximately 10-fold excess of library (108 cells) was incubated in a 0.5 mL of approximately 7 nM FcRilIA for 1 hr. The mixture was sorted by FACS, selecting top 1.2% of binders. Selected yeast cells were grown in selective media containing glucose and reinduced in selective media containing MlibruIm screen was repeated a second time and the sort gate was set to collect the top 0.2% of binders. The selected yeast cells were then grown under selective conditions in glucose. This culture was than used to harvest DNA. Inserts containing the Fe domain were amplified by PCR and cloned into the nucleotide sequence encoding 4-4-20 variable domain using methods already described. Approximately 90 Fc mutants were screened by 4-4-20 ELISA and ADCC and the resultant positive mutants are shown in Table 20. Table 20: Mutants selected by FACS using an Equilibrium screen with concentrations of FcRUIA of approximately 7 nM. (Table Removed) [00540] A kinetic screen was also implemented to identify mutants with improved K0ff in binding FcyRJIIA Conditions were established for screening the P396L library using a strain with the P396L Fe variant displayed on the yeast surface. Briefly cells grown under inducing conditions were incubated with 0.1 biotinylated FcRflIA -linker-avitag monomer for 1 hr. The cells were washed to remove the labeled ligand. Labeled cells were then incubated for different times with 0.1 pM unlabeled FcRflIA-linker-avitag monomer, washed and then stained with SA;PE for FACS analysis (FIG. 22). Cells were also stained with goat anti-human Fc to show that the Fe display was maintained during the experiment. [00541] Based on the competition study it was determined that a 1 minute incubation resulted in approximately 50% loss of cell staining. This time point was chosen for the kinetic screen using the P396L library. Approximately 10-fold excess of library (l0- cells) was incubated with 0.1µM biotinylated FoyRILIA-linker-avitag monomer in a 0.5 mL volume. Cells were washed and then incubated for 1 minute with unlabeled ligand. Subsequently the cells were washed and labeled with SAPE. The mixture was sorted by FACS, selecting the top 0.3% of binders. Selected yeast cells were grown in selective media containing glucose and reinduced in selective media containing galactose. The kinetic screen was repeated a second time and the sort gate was set to collect the top 0.2% of binders. The nonseleted P396L library was compared to the yeast cells selected for improved binding by FACS (FIG. 23). The histograms show the percentage of cells that are costained with both FcRUJA /PE and goat anti-human Fe/FITO (upper right). yeast cells from the second sort were then grown selective conditions in glucose. This culture was than used to harvest DNA. Inserts containing the Fc domain were amplified by PCR and cloned into the nucleotide sequence encoding 4-4-20 variable domain using methods described above. Approximately 90 Fc mutants were screened by 4-4-20 ELISA and ADCC and the resultant positive mutants are shown in Table 21. Table 21: Mutants selected by FACS using a Kinetic screen using eguimolar amounts of unlabeled CDI6A for 1 minute. (Table Removed) Screens 4 and 5: Combining the Solid Phase FcRIiB Depletion Step with FcyRIILI Selection by FACs Sort, using the FcyRIIIA 158V allele 1005431 Analysis of Fc variants from Screen I showed that the mutations that were selected from the secondary screen had improved binding to both FcRiIIA and FcyRIIB. Therefore, the data suggested that sequential depletion and selection using magnetic beads (solid phase) under the established conditions did not efficiently select for differential binding of FcRIIIA and FcyRIIB. Therefore, in order to screen more effectively for mutants that bind FcRfliA, while having reduced or no binding to FcRUB, the solid phase FcRIIB depletion step was combined with FcRTIIA selection by FACs sort. This combination identified Fc variants that bind FcyRIIIA with greater or equal affinity than wild-type Fc. [005441 A 10-fold excess of the naIve library (—l0- ) was incubated with magnetic beads coated with FcRIIB. Yeast bound to beads were separated from the non-bound fraction by placing the tube containing the mixture in a magnetic field. Those yeast cefls that were not bound to the beads were removed and placed in fresh media and subsequently reinduced in media containing galactose. The FcRflB depletion by magnetic beads was repeated 5 times. The resulting yeast population was analyzed and found to show greater than 50% cell staining with goat anti-human Fc and a very small percentage of cells were stained with FcRILIA. These cells were then selected twice by a FACS sort using 0.1 pM (data not shown). The FcRUJA was the I 58V allotype. Yeast cells were analyzed for both FcRUJA and FcRLIB binding after each sort and compared to binding by wild-type Fc domain (FIGs. 24 A-B). [00545] The selected yeast cells from the second sort were then grown under selective conditions in glucose. This culture was then used to harvest DNA. Inserts containing the Fc domain were amplified by PCR and cloned into the nucleotide sequence encoding 4-4-20 variable domain. Approximately 90 Fc mutants were screened by 4-4-20 ELISA and ADCC and the resultant positive mutants are shown in Table 22 (mutants 61-66). Table 22: Mutants selected by magnetic bead depletion using beads coated with CD32B and final selection by FACS using FcyRUIA (Table Removed) [005461 Screening of Fc mutants using the 158F allele ofFcyRIIIA: Two different alleles of FcRUJA receptor exist that have different binding affinities for the IgGl Fc domain (Koene etaL, 1997, Blood 90: 1109-1114; Wu etal., 1997,1 Clin. Invest. 100: 1059-70). The 158F allele binds to the Fc domain with a binding constant 5-10 fold Lower than the I 58V allele. Previously all of the Pc screens using yeast display were done using the high binding 1 58V allele as a ligand. In this experiment~ Fe mutants were selected from the FcRIIB depleted yeast population using biotinylated FcyRILlAl58F-linker-avitag monomer as a ligand. The sort gate was set to select the top 0.25 percent FcRIIIA 158F binders. The resulting enriched population was analyzed by FACS (FIG. 24B). Individual clones were then isolated and their binding to different FcRs were analyzed by FACS (FIG. 24B): Analysis of individual clones from the population rsulted in the identification of a single mutant harboring 5 mutations MgFc67 (V284M, S298N, K334E, R355W, R416S), which had an enhanced binding to FcRflIA and a reduced binding to FcRLIB. Secondary Screen of Mutants by an ADCC assay For Screens 1, 2, and 3: [00547] Mutants that were selected in the above screens were then analyzed using a standard ADOC assay to determine the relative rates of lysis mediated by ch4-4-20 harboring the Fc mutants. ch4-4-20 antibodies carrying the Fe variants were constructed above. SK-BR3 cells were used as targets and effector cells were PBMC that were isolated from donors using a Ficoll gradient, as described supra (Section 6.7). The ADOC activity results for the mutants are summarized in Table 23. [00548] As seen in Table 23, mutants isolated using the above primary and secondary screens based on FcRLIB depletion and FcyRIIIA selection showed enhanced ADCC activity relative to wild-type. Table 23: Analysis of ADCC mediated by 4-4-20 anti-Fluorescein antibody on SKBR3 cells coated with Iluorescein. Relative rate of (Table Removed) [00549] Mutants 37, 38, 39,41,43 were analyzed using 0.5 p.g/mL ch4-4-20. All other antibodies were tested at 1 jtg/mL. All rates were normalized to wild type ch4-4-20 (IgGl). [00550] Mutants were additionally cloned into the heavy chain of antitumor monoclonal antibody 4D5 (anti-HER2fneu) and anti-CD2O monoclonal antibody 2H7 by replacing the Fc domain of these monoclonal antibodies. These chimeric monoclonal antibodies were expressed and purified and tested in an ADOC assay using standard into 29311 cells and purification over protein G column. The chimeric 4D5 antibodies were tested in an ADCC assay using SK-BR3 cells as targets (FIG. 25), whereas the chimeric 2H7 antibodies were tested in an ADCC assay using Daudi cells as targets (FIG. 26). [00551] Secondaiy Screen of Mutants via BIA core: Mutants that were selected in the above screens were then analyzed by BlAcore to determine the kinetic parameters for binding FcRIIIA(158V) and FcyRIIB. The method used was similar to that disclosed in Section 6.8, supra. [00552] The data displayed are K0ff values relative to wild type off rates as determined from experiments using the Fc mutants in the ch4-4-20 monoclonal antibody. Relative numbers greater than one indicate a decrease in K~1 rate. Numbers less than one indicate an increase in off rate. [00553] Mutants that showed a decrease in off rates for FcRIIIA were MgFc38 (K392, P396L), MgFc43(Y3 19F, P352L, P396L), MgFc42( D221E, D270E, V308A, Q31 111, P396L, G402D), MgFc43b (K288R, T307A, K344E, P396L), MgFc44 (K334N, P396L), MgFc46 (P217S, P396L), MgFc49 (K261N, K21OM, P396L). Mutants that showed a decrease in off rate for FcRLIB were, MgFc38(K392, P396L), MgFc39 (E293V, Q295E, A327T), MgFc43 (K288R, T307A, K344E, P396L), MgFc44 (K334N, P396L). The Biacore data is summarized in Table 24. (Table Removed)6.10 PBMC MEDIATED ADCC ASSAYS [00554] MATERIALS AND METHODS [00555] Fc variants that show improved binding to FcR.IIIA were tested by PBMC based ADCC using 60:1 effector:target ratio. Two different tumor model systems were used as targets, SK-BR3 (anti-IIER2/neu) and Daudi (anti-CD2O). Percent specific Lysis was quantitated for each mutant. Linear regression analysis was used to plot the data setting the maximal percent lysis at 100%. [00556] ADCC is activated on immune system effector cells via a signal transduction pathway that is triggered by an interaction between low affinity FcyR and an immune complex. Effector cell populations were derived from either primary blood or activated monocyte derived macrophages (lvfDM). Target cells were loaded with europium and and subsequently incubated with effector cell populations. Europium works the same way as 5tCr, but it is non-radioactive and the released europium is detected in a fluorescent plate reader. Lymphocytes harvested from peripheral blood of donors (PBM) using a Ficoll-Paque gradient (Pharmacia) contain primarily natural killer cells (NK). The majority of the ADCC activity will occur via the NK containing Fc'yRIIIA but not FcRTIB on their surface. [00557] Experiments were performed using two different target cell populations, SK¬BR- 3 and Daudi, expressing HBR2/neu and CD2O, respectively. ADCC assays were set up using Ch4-4-201 FITC coated SK-BR-3, Ch4D5/SKBR3, and Rituxan/Daudi (data not shown). Chimeric MAbs were modified using Fe mutations identified. Fe mutants were cloned into Ch4DS. Purified Ab was used to opsonize SK-BR-3 cells or Daudi cells. Fe mutants were cloned into Ch4D5. [00558] RESULTS. Fe mutants showed improved PBMC mediated ADCC activity in 5K BR3 cells (FIG. 29). The plot shows linear regression analysis of a standard ADCC assay. Antibody was titrated over 3 logs using an effector to target ratio of 75:1. % lysis = (Experimental release — SR)/(MR-SR) * 100. [005591 Fe mutants showed improved PBMC mediated ADCC activity in Daudi cells (FIG. 30). 6.11 MONOCYTE DERIVED MACROPHAGE (MDM) BASED ADCC ASSAYS [005601 FcR dependent tumor cell killing is mediated by macrophage and NK cells in mouse tumor models (Clynes et aL, 1998, PNAS USA, 95: 652-6). Elutriated monocytes from donors were used as effector cells to analyze the efficiency Fe mutants to trigger cell cytotoxicity of target cells in ADCC assays. Expression patterns of FcRI, FcR3A, and FcR2B are affected by different growth conditions. FcR expression from frozen monocytes cultured in media containing different combinations of cytokines and human serum were examined by FACS using FeR specific MAbs. (FIG. 31). Cultured cells were stained with FcR specific antibodies and analyzed by FACS to determine MDM FcR profiles. Conditions that best mimic macrophage in vivo FcR expression, i.e., showed the greatest fraction of cells expressing CDl6 and CD32B were used in a monocyte derived macrophage (MDM) based ADCC assay. For the experiment in FIG. 31, frozen elutriated monocytes were grown for 8 days in DMEM and 20% PBS containing either M-CSF (condition I) or GM-CSF (condition 2). For the experiment in FIG. 32, frozen elutriated monocytes were cultured for 2 days in DMBM and 20% FBS containing GM-CSF, IL-2 and Serum free conditions have also been developed which allow for lugh levels of CDl6 and CD32B expression (data not shown). Briefly, purified monocytes were grown for 6-8 days in Macrophage-SFM (Invitrogen) containing GM-CSF, M-CSF, IL-6, IL-b, and IL-1J3. While the incidence of CD32B+/CDI6+ cells in these cultures is highest using a mixture of cytokines, combinations of two of more cytokines will also enhance FcR expression (M-CSF/IL-6, M-CSF/IL-l0; or M-CSF/IL-lp). For ADCC assays, IFNy is added for the final 24-48 hours. [005611 MDM based ADCC required incubation times of16 hrs to observe target cell killing. Target cells were loaded with Indium-I 11 which is retained for long incubations within the target cells. Indium release was quantitated using a gamma counter. All other reagents, Abs and target cells, were similar to the PBMC based ADCC assay. ADCC activity due to FcyRI can be efficiently blocked using the anti-FeRI blocking antibody (M21, Ancell). The assay conditions differ sllghfly from the PBMC based assay. 20:1 target to effeector; 18-14 hr incubation at 37C. [00562] Fc mutants that show improved PBMC ADCC, increased binding to FcRIIIA, or decreased binding to FcyR.UB were tested (FIG. 32). 6.12 EFFECT OF Fc MUTANTS ON COMPLEMENT ACTIVITY [005631 Fc mutants were originally identified based on their increased binding to FcyRIIIA. These mutants were subsequently validated for their improved affinity for all low affinity receptors and in many cases improved activity in ADCC mediated by PBMC. In vivo antibody mediated cytotoxicity can occur through multiple mechanisms. In addition to ADCC other possible mechanisms include complement dependent cytotoxicity (CDC) and apoptosis. The binding of Clq to the Fc region of an immunoglobulin initiates as cascade resulting in cell lysis by CDC. The interaction between Clq and the Fe has benn studies in a series of Fe mutants. The results of these experiments indicate that Clq and the low affinity FcR bind to overlapping regions of the Fe, however the exact contact residues within the Fe vary. [00564] Mutants that showed improved ADCC in the PBMC based assay were exaqmined for their effect in CDC. Antibodies were analyzed in the anti CD2O Ch-mAb, 2H7. We detected improved CDC for each mutant ch-mAb tested. Interestingly even though these mutants were seleted for their improved ADCC they also show enhanced CDC [00565] MATERIALS AND METhODS. ODO assay was used to test the Fe mutants using anti-CD2O and Daudi cells as targets. Guinea Pig Serum was used as the source for complement (US Biological). The CDC assay was similar to PBMC based loaded with europium and opsonized with CIIMAb. kiowever complement, guinea pig serum, wasadded instead of effector cells. FIG. 33 shows a flow chart of the assay. Anti-CD2O ChMab over 3 orders of magnitude was titrated. % lysis was calculated. Daudi cells, (3 x 106) were labeled with BADTA reagent. 1 x 1 ~4 cells were aliquoted into wells in a 96 well plate. Antibodies were titrated into the wells using 3 fold dilutions. The opsonization reaction was allowed to proceed for 3 0-40 minutes at 370 C in 5% CO2. Guinea pig serum was added to a final conc. of 20%. The reaction was allowed to proceed for 3.5 hrs at 370 C in 5% CO2. Subsequently, 100 uls of cell media was added to the reaction and cells were spun down. For detection 20 uls of the supematant was added to 200 uls of the Europium solution and the plates were read in the Victor2(Wallac). [00566] RESULTS: All mutants that show improved binding for either activating FcR or Clq were placed in the CDC assay (FIG. 34). Fc mutants that showed enhanced binding to FcTRflIA also showed improved complement activity Each of the mutants show enhanced complement activity compared to wild type. The mutants tested are double mutants. In each case one of the mutations present is P396L. [00567] To determine whether the increase in CDC correlated with increased binding of Clq to IgGl Fc binding between the two proteins was measured in realtime using surface plasmon resonance. In order to examine the binding between Clq and an IgOl Fc the Fc variants were cloned into an anti-CD32B ch-mAb, 2B6. This allowed us to capture the wt and mutant antibodies to the glass slide via soluble CD32B protein (FIG. 36A). Three of the four mutants tested in CDC were also examined in the Biacore. All 3 showed greatly enhanced K0ff compare to wild type Fc (FIG. 36B). Biacore format for Clq binding to 2B6 mutants demonstrate enhanced binding of mutants with P396L mutation (FIG. 37). Mutation D270E can reduce Clq binding at different extent. A summary of the kinetic analysis of FcR and Clq binding is depicted in the table 25 below. (Table Removed) 6.13 DESIGNING Fe VARIANTS WITH DECREASED BINDING TO FcyRJJB [00568] Based on a selection for Fc mutants that reduce binding to FcRIIB and increase binding to FcRIIA 13111 a number of mutations including D270E were identified. Each mutation was tested individually for binding to the low affinity Fc receptors and their allelic variants. [00569] D270E had the binding characteristics that suggested it would specifically reduce FcRIIB binding. D270E was tested in combination with mutations that were previously identified based on their improved binding to all FeR. [00570] RESULTS. As shown in Tables 26 and 27 and FIGs. 38 and 39 addition of D270E mutation enhances FcRIIIA and FcRll.A H 131 binding and reduces binding to FcyRIIB. FIG. 40 shows the plot of MDM ADCC data against the Koff as determined for CD32A 1113111 binding for select mutants. TABLE 26. OFF RATE (us) of FcR BINDING TO WILD TYPE AND MUTANT CHIMERIC 4D5 Ab OBTAINED BY BIA CORE ANALYSIS (Table Removed) TABLE 27 KINETIC ChARACTERISTICS OF 4D5 MUTANTS 3aVl58 3aFlSS2bfcag] aR13lFcagl2aHl3lFcag1 4D5Mutants [00579] FcTRflA 13111 were analyzed and resonance responses were normalized at the level of response obtained for a wild type chimeric 4D5 antibody. Kinetic parameters for the binding of the FcRs to the chimeric 4D5 antibody were obtained by fitting the data at two different FcR concentrations: 400µM and 800 nM for both FcRIHA V158 and FcRIIIA 158F; 100 nM and 200 nM for both Fc~yR1IA and FcyRIJB. [00578] Table 28 presents the off rate for each of the four receptors analyzed in association with the indicated variant Fe regions. Table 28. Off rate (us) of FcR binding to wild type and mutant chimeric 4D5 Ab obtained by BlAcore analysis (Table Removed) 6.15 ADCC ASSAY OF Fe MUTANTS [00580] Fc mutations identified in Example 6.14 as comprising increased affinity for FeyIIIA and/or FeyIIA were analyzed for their relative ADCC activity. [00581] Materials and Methods [00582] Details regarding ADCC assays are found in Section 6.7. In this assay, HT29 colon carcinoma cells (ATCC Accession No. HTB-38) loaded with Indium-ill were used as targets and effector cells were PBMC that were isolated from donors using a Ficoll gradient. Target cells were opsonized with chimeric 4D5 antibodies comprising the variant Fc regions at final concentrations of 2-5 000 ng/ml. Opsonized target cells were then added to effector cells to produce an effector:target ratio of 50:1 and incubated for 18 hours at 370C, 5% CO2. After incubation, cells were centrifuged at —220xg for five minutes at 100C. The level of Indium-l 11 in the supernatant was recorded by a gamma counter. [00583] Results [00584] Chimeric 4D5 antibodies comprising variant Fe regions MGFc88 (F243L,R292P,Y300L,V3051,P396L), MGFc88A (F243L,R292P,Y3 OOL, P396L) and MGFc 155 (F243L,R292P,Y300L) were selected based on enhanced affinity for FcyRIIIA and/or FcTIIA and tested for their ADCC activity. FIGS. 41 A & B show that the Fe variants tested exhibit enhanced ADCC activty relative to wild type antibody at opsonization concentrations above 20 ng/ml in a concentration dependent manner. The data indicate that Fe mutants identified as comprising increased affinity for FcRHIA are also likely to exhibit enhanced ADCC activity. 6.16 Fc MUTANT MEDIATED TUMOR GROWTH CONTROL IN AN IN VIVO TUMOR MODEL [00585] Fe mutations identified as comprising enhanced affinity for FeyIIIA and/or FeyllA were further analyzed for relative efficacy of tumor control using an in vivo tumor model system. [00586] Materials and Methods 100587] Antibodies harboring Fe mutants were tested for anti-tumor activity in a murine xenograft system. Balbe/nude mice are subcutaneously injected with 5x106 Daudi gionitored for general signs of illness, e.g.. weight gain/loss and grooming activity. Without treatment, this model system results in 100 % mortality with an average survival time of approximately 2 weeks post tumor cell inoculation. Treatment consists of doses of wild-type antibody or antibody comprising a variant Fc region administered at weekly intervals. Animals administered buffer alone at the same intervals serve as a control. Tumor weight is calculated based on the estimated volume of the subcutaneous tumor according to the formula (width2 X length)/2. [005881 Results [00589] At weekly intervals, mice inoculated with Daudi cells received wild-type humanized 2B6 ("h2B6"), humanized 2B6 comprising mutant FcMGOO88 (F243L, R292P, Y300L, V3051 P396L) ("h2B6 0088") or buffer alone. Wild-type and Fc mutant h2B6 antibody showed similar levels of tumor suppression at the highest dose schedule tested, weekly doses of 25 jig (FIGs. 42 A and B). However, significant differences in antibody efficacy were observed when dosages were reduced. 100 and 10 fold reduction in wild-type b2B6 dosages provided no greater tumor control than administration of buffer alone (FIG. 42 A). In contrast, h2B6 0088 provided significant protection at weeldy doses of 2.5µg and at least limited protection at weekly doses of .25 pg (FIG. 42 B). [00590] The protection conferred by even the lowest dose of Fe mutant antibody was confirmed in survival comparisons. At 11 weeks, 4 out of 7 mice remained alive in the group treated with 0.25 jig doses of b2B6 0088 compared to only 1 out of 7 in the group treated with the same dose of wild-type b2B6 (FIGs. 43 A & B) [00591] The invention described and claimed herein is not to be limited in scope by the specific embodiments herein disclosed since these embodiments are intended as illustration of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. [005921 Throughout this application various publications are cited. Their contents are hereby incorporated by reference into the present application in their entireties for all purposes 11183-055-228 Seq. Listing.txt SEQUENCE LISTING (Sequence Removed) We claim : 1. A polypeptide comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, such that said variant Fc region of said polypeptide binds an FcyRlIIA with a greater affinity relative to the binding affinity exhibited by a such polypeptide if comprising a wild-type Fc region and wherein said at least one amino acid modification comprises a set of substitutions selected from the group consisting of: (1) a substitution at position 243 with leucine, at position 292 with proline, al position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; (2) a substitution at position 243 with leucine, at position 292 with proline, al position 300 with leucine, and at position 396 with leucine; (3) a substitution at position 243 with leucine, at position 292 with proline, and at position 300 with leucine; (4) a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; (5) a substitution at position 243 with leucine, at position 292 with proline, and at position 305 with isoleucine; (6) a substitution at position 243 with leucine and at position 292 with proline: and (7) a substitution at position 273 with phenylalanine; wherein the positions are numbered according to the EU index as in Kabat. 2. The polypeptide of claim 1, wherein said variant Fc region of said polypeptide additionally specifically binds FcyRIIB with a lower affinity than the binding affinity exhibited by such polypeptide if comprising a wild-type Fc region. 3. The polypeptide of claim l,or 2, wherein the Fc region is a human IgG Fc region. 4. The polypeptide of claim 3, wherein the human IgG Fc region is a human IgGl. IgG2, IgG3, or IgG4 Fc region. 5. The polypeptide of claim 1 or 2, wherein said polypeptide is an antibody, or a fragment of an antibody, that contains said variant Fc region. 6. The antibody or fragment thereof of claim 5. wherein said antibody is a monoclonal antibody, a humanized antibody, or a human antibody. 7. The antibody or fragment thereof of claim 5, wherein said antibody is a humanized antibody. 8. The antibody or fragment thereof of claim 5, wherein said antibody comprises a variable domain which binds to CD16A or CD32B. 9. The antibody or fragment thereof of claim 5, wherein said antibody is 2B6. 10. The antibody or fragment thereof of claim 5. wherein said antibody is a humanized version of 2B6. 11. The antibody or fragment thereof of claim 5, wherein said antibody competitively inhibits the binding of 2B6 antibody to CD32B. 12. A nucleic acid comprising a nucleotide sequence encoding the polypeptide of any ol' claims 1 or 2. 13. A vector comprising the nucleic acid of claim 12. 14. The vector of claim 13 which is an expression vector. 15. A host cell comprising the nucleic acid of claim 14. 16. A method for recombinantly producing the polypeptide of any of claims 1 or 2. said method comprising: (i) culturing in a medium a host cell comprising a nucleic acid encoding said polypeptide under conditions suitable for the expression of said polypeptide; and (ii) recovery of said polypeptide from said medium. 17. The antibody or fragment thereof of claim 5. wherein said antibody or said fragment additionally specifically binds a cancer antigen, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type fc region, such that said therapeutic antibody specifically binds FcyRlIlA with a greater affinity than such therapeutic antibody if comprising a wild-type Fc region binds FcyRlIlA and wherein said at least one amino acid modification comprises a set ol" substitutions selected from the group consisting of: (1) a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, at position 305 with isoleucine, and at position 396 with leucine; (2) a substitution at position 243 with leucine, at position 292 with proline, at position 300 with leucine, and at position 396 with leucine; (3) a substitution at position 243 with leucine, at position 292 with proline, and al position 300 with leucine; (4) a substitution at position 243 with leucine, at position 292 with proline, and at position 396 with leucine; (5) a substitution at position 243 with leucine, at position 292 with proline, and at position 305 with isoleucine; (6) a substitution at position 243 with leucine and at position 292 with proline: and (7) a substitution at position 273 with phenylalanine. 18. The antibody, or said fragment thereof, of claim 17, wherein said variant Fc region of said antibody or fragment additionally specifically binds FcγRIIB with a lower affinity than the binding affinity exhibited by such antibody or such fragment if comprising a wild-type Fc region. 19. The antibody, or fragment thereof, of claim 17 or 18. wherein said therapeutic antibody mediates enhanced antibody dependent cell mediated cytotoxicity relative to a comparable therapeutic antibody comprising a wild-type Fc region. 20. The antibody , or fragment thereof, of claim 17 or 18, wherein said therapeutic antibody is trastuzumab, rituximab, IC14, PANOREX™, IMC-225, V1TAX1N™. Campath 1H/LDP-03, LYMPHOCIDE™, or ZEVEIN™. 21. The antibody, or fragment thereof, of claim 17 or 18, wherein said cancer antigen is MAGE-1, MAGE-3, BAGE, GAGE-1. GAGE-2, N-acetylglucosaminyltransferase. p15, beta-catenin, MUM-1, CDK4, HER-2/neu, human papillomavirus-E6, human papillomavirus-E7, or MUC-1. 22. The use of the antibody, or fragment thereof, of claim 17 or 18, in the preparation of a medicament for the treatment of cancer in a patient having a cancer characterized by said cancer antigen. 23. The use of claim 22, wherein said cancer antigen is MAGH-1, MAGK-3, BAGK. GAGE-1, GAGE-2, N-acetylglucosaminyltransferase, p15, beta-catcnin, MUM-1. CDK4, HER-2/neu, human papillomavirus-E6, human papillomavirus-K7, or MUC-1. 24. The use of claim 22, wherein said cancer antigen is a breast, ovarian, prostate, cervical, or pancreatic carcinoma antigen. 25. The use of claim 22, wherein said medicament additionally comprises a chemotherapcutic, radiothcrapeutic, hormonal therapeutic, or immunotherapeutic composition. 26. The use of claim 22, wherein said patient is human. 27. A composition comprising a therapeutically effective amount of the polypeptide of claim 1 or 2. and a pharmaceutically acceptable carrier. 28. A composition comprising a therapeutically effective amount of the antibody of claim 5, and a pharmaceutically acceptable carrier. 29. A composition comprising a therapeutically effective amount of the antibody of claim 6, and a pharmaceutically acceptable carrier. 30. A composition comprising a therapeutically effective amount of the therapeutic antibody of claim 17 or 18, and a pharmaceutically acceptable carrier. 31. The composition of claim 30, further comprising one or more additional anti-cancer agents. 32. The compositions of claim 31. wherein said one or more anti-cancer agents is a chemotherapeutic agent, a radiation therapeutic agent, a hormonal therapeutic agent, or an immunotherapeutic agent. 33. A nucleic acid comprising a nucleotide sequence encoding a heavy chain of an antibody of claim 5. 34. A vector comprising the nucleic acid of claim 33. 35. The vector of claim 34 which is an expression vector. 36. A host cell comprising the nucleic acid of claim 35. 37. A method for recombinantly producing the antibody of claim 1. said method comprising: (i) culturing in a medium a host cell comprising (a) a nucleic acid comprising the nucleotide sequence encoding the light chain of said antibody; and (b) a nucleic acid comprising the nucleotide sequence encoding the heavy chain of said antibody, under conditions suitable for the expression of said antibody: and (ii) recovery of said antibody from said medium. 38. The use of the polypeptide of claim 1 in a medicament for the treatment or management of cancer in a patient having a cancer characterized by a cancer antigen, wherein said polypeptide binds to said cancer antigen. 39. The antibody of claim 5, wherein said antibody has an enhanced ADCC activity relative to the ADCC activity of said antibody if comprising a wild type Fc region. 40. The polypeptide of any of claims 1 or 2, wherein said variant Fc region further comprises one or more of the amino acid modifications listed in table 5. 6, 7, or 8. |
|---|
| Patent Number | 269638 | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 2052/DELNP/2008 | |||||||||||||||
| PG Journal Number | 45/2015 | |||||||||||||||
| Publication Date | 06-Nov-2015 | |||||||||||||||
| Grant Date | 29-Oct-2015 | |||||||||||||||
| Date of Filing | 10-Mar-2008 | |||||||||||||||
| Name of Patentee | MACROGENICS, INC. | |||||||||||||||
| Applicant Address | 1500 EAST GUDE DRIVE, ROCKVILLE, MD 20850, U.S.A | |||||||||||||||
Inventors:
|
||||||||||||||||
| PCT International Classification Number | A61K 39/395 | |||||||||||||||
| PCT International Application Number | PCT/US2006/031201 | |||||||||||||||
| PCT International Filing date | 2006-08-10 | |||||||||||||||
PCT Conventions:
|
||||||||||||||||