Allotyping of Complement Components

Studies on the genetics of complement proteins were originally initiated by the discovery of complement deficiencies in animals and man. From these studies, it has become apparent that most complement components are polymorphic, some with several tens of different allotypes. The study of the major histocompatibility complex (MHC)-encoded complement components C4A and C4B was particularly rewarding because of their association with human lymphocyte antigens (HLA) and because of their presence as closely linked loci, both of which encode for a large number of allelic variants (1 ).