Human Immunoglobulin A

Abstract

ONE of the important recent advances in modern immunology is the recognition that antibody activity is associated with a group of multichain proteins of varying mobility and molecular size. Normal serum probably contains hundreds of different antibodies, each being individually specific in its sequence of amino acids. This extensive heterogeneity of antibodies has been simplified somewhat since antibodies can be grouped into five major immunoglobulin classes as outlined in Table 1. This classification is based on chemical and physical, as well as immunologic, differences in these groups of proteins. Each of the major classes can be further subdivided into various subclasses . . .