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November 26, 1982

Use and Interpretation of Diagnostic Immunologic Laboratory Tests

JAMA. 1982;248(20):2734-2758. doi:10.1001/jama.1982.03330200158029


Antibodies—The Secreted Products of Plasma Cells  Antibodies are synthesized and secreted primarily by plasma cells, the progeny of B lymphocytes. Since many different clones of cells participate in the immune responses to a single antigen, antibodies are heterogeneous with respect to their structure and function. However, proteins carrying antibody activity, all of which migrate electrophoretically as γ-globulins, belong to different immunoglobulin classes (ie, IgG, IgA, IgM, IgD, and IgE).All immunoglobulins are composed of two polypeptide chains of different molecular size, the light and heavy chains. A monomeric immunoglobulin molecule consists of two heavy and two light chains. These polypeptide chains are arranged in the shape of a Y (Fig 20-1). The arms of the Y are composed of the amino-terminal halves of the heavy chain and the entire light chain, while the carboxyterminal halves of the two heavy chains constitute the stem. The arms and the