Associations between HLA Antigens and Disease *Based on a lecture given in a Symposium 'Cellular Antigens and Disease' at the 30th Annual Meeting of the American Association of Blood Banks, Atlanta, USA, 15th November 1977.

occur more frequently in persons who have inherited particular HLA antigens. Genes controlling the inheritance of the HLA antigens are located on chromosome 6, and the major histocompatibility complex (MHC) in man involves at least four gene loci (A, B, C and D) controlling at least 64 HLA specificities. Recently, certain genes have been identified which code for a group of HLA alloantigens demonstrable on B-cell lymphocytes, but not on T-lymphocytes or platelets.1 In the mouse, B-lymphocyte antigens are referred to as I A, or immune response-associated antigens and, initially therefore, human B-cell antigens were referred to as wlA. Some, if not all, such antigens are, however, closely related to the products of the HLA-D locus2 and the WHO Tissue Typing Nomenclature Committee has currently designated them DR (for D related), followed by the letter 'w' to indicate that their designation is still provisional. The probable gene structure of the MHC on chromosome 6 is outlined in Figure 1. The extensive search for associations between HLA antigens and specific diseases in man was stimulated by the demonstration of genetic linkage in mice between the murine histocompatibility complex, H?2, and resistance to virus induced