SUBCLASSES OF HUMAN GAMMA-2-GLOBULIN BASED ON DIFFERENCES IN THE HEAVY POLYPEPTIDE CHAINS.

Three subclasses of human gamma(2)-globulin (IgG) molecules were detected in normal human serum with antiserums prepared in monkeys. These subclasses, designated gamma(2a)-, gamma(2b)-, and gamma(2c)-globulins, have antibody activity. The distinguishing antigenic characteristics of each subclass were associated with the heavy polypeptide chains and the F (fast) fragments resulting from treatment of gamma(2)-globulins with papain.