The structure of human immunoglobulins

General structural features of human Ig proteins are reviewed. The basic four-chain polypeptide structure is described with particular emphasis on IgG as a model for all Ig classes. The dual biologic role of antibody with antigen-binding and the Fc-associated class-specific effector functions is discussed. Certain aspects of Ig structure are highlighted in order to facilitate understanding of symposium topics related to Ig structure and function. Variable (V) region Ig structure, hypervariable segments in the V-regions, idiotypic determinants, and clonal switch mechanisms which permit the synthesis of IgM, IgG and IgA are presented in greater detail. Summary comments include a brief discussion of the genetic control of immunoglobulin synthesis.