Antibodies and Immunoglobulins

Abstract

Antibody Response.— Several days elapse following primary antigen administration before antibody is detected in the serum. In this interval, antigen recognition and immune cell sensitization are followed by development of antibody synthetic capacity and proliferation of antibody producing cells. A considerable amount of antibody synthesis must occur before circulating antibody becomes detectable. At least 10¹⁶molecules of antibody have to be synthesized and be retained intravascularly in an 132 lb (60 kg) man to be detectable as 0.001 mg antibody per milliliter of serum. Antibody activity may be present in one or more components of the serum immunoglobulin system. Four classes of immunoglobulins have been identified: IgG (γG, 7S γ2-globulin), IgA (γA, β2A-globulin), IgM (γM, 18S γ1-macroglobulin) and IgD (yD). The distribution of these proteins, as detected by immunoelectrophoresis, is shown in Fig 1. The principal properties of the four major immunoglobulin classes were reviewed in a companion report.