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antibody [2018/02/26 18:10] (current)
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|+||'''Antibodies''' are [[blood]] circulating glyco[[protein]]s termed [[immunoglobulins]] that are secreted by plasma cells (differentiated B lymphocytes) in response to immune stimulation. They constitute what is known as the humoral immune response, which is highly specific. Alternatively, B lymphocytes may differentiate into "memory cells" which display antibody molecules on their cell surface contributing to [[active immunity]] for future exposure to an antigen. There are five major classes of antibodies that differ upon their location in the body, structure, and function: IgA, IgD, IgM, IgG, IgE. During a typical bacterial or viral infection, the major classes that operate are IgM and IgG.|
|+||Antibodies recognize and bind tightly to small molecules (peptide or carbohydrate) termed [[antigens]]. Antigens may be free floating in the blood, or bound to the plasma membrane of a pathogen or presented at the surface by another immune cell. An antibody may directly neutralize a pathogen, mark a microbe for attack, or be used to bind to antigens presented by other cells for further immune stimulation.|