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Monoclonal antibody therapy is a form of immunotherapy that uses monoclonal antibodies (mAb) to specifically bind to specific cells or proteins. This may then stimulate the patient's immune system to attack those cells. Alternatively, in radioimmunotherapy a radioactive dose localizes on a target cell line, delivering lethal chemical doses. More recently antibodies have been used to bind to molecules involved in T-cell regulation to remove inhibitory pathways that block T-cell responses, known as immune checkpoint therapy. It is possible to create a mAb specific to almost any extracellular/ cell surface target. Research and development is underway to create antibodies for diseases (such as rheumatoid arthritis, multiple sclerosis, Alzheimer's disease, Ebola and different types of cancers). ==Antibody structure and function== Immunoglobulin G (IgG) antibodies are large heterodimeric molecules, approximately 150 kDa and are composed of two kinds of polypeptide chain, called the heavy (~50kDa) and the light chain (~25kDa). The two types of light chains are kappa (κ) and lambda (λ). By cleavage with enzyme papain, the Fab (''fragment-antigen binding'') part can be separated from the Fc (''fragment constant'') part of the molecule. The Fab fragments contain the variable domains, which consist of three antibody hypervariable amino acid domains responsible for the antibody specificity embedded into constant regions. The four known IgG subclasses are involved in antibody-dependent cellular cytotoxicity. The immune system responds to the environmental factors it encounters on the basis of discrimination between "self" and "non-self". Tumor cells are generally not specifically targeted by the immune system, since tumor cells are the patient's own cells. Tumor cells, however are highly abnormal, and many display unusual antigens. Some such antigens are inappropriate for the cell type or its environment. Some normally present only during the organisms' development (e.g. fetal antigens).〔 Some are rare or absent in healthy cells, and are responsible for activating cellular signal transduction pathways that cause unregulated tumor growth. Examples include ErbB2, a constitutively active cell surface receptor that is produced at abnormally high levels on the surface of approximately 30% of breast cancer tumor cells. Such breast cancer is known as HER2-positive breast cancer. Antibodies are a key component of the adaptive immune response, playing a central role in both in the recognition of foreign antigens and the stimulation of an immune response to them. The advent of monoclonal antibody technology has made it possible to raise antibodies against specific antigens presented on the surfaces of tumors.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Monoclonal antibody therapy」の詳細全文を読む スポンサード リンク
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