Serological and Cellular Recognition of Human Histocompatibility Antigens

Abstract

The human major histocompatibility complex (HLA) consists of a region of chromosome 6 (Smith et al., 1976; Francke and Pellegrino, 1977) that contains a number of genes that code for highly polymorphic integral membrane glycoproteins. The allelic products of these genes are generally detected by their reactivity with human alloantisera from multiparous women or from individuals immunized either with lymphocytes (deliberately or by blood transfusions) or by organ grafts. Currently serologically defined are the genes HLA-A, -B, -C, and -DR. HLA-A, -B, and -C code for 44,000-dalton molecules that are expressed noncovalently associated with β ₂-microglobulin (Springer and Strominger, 1976; Grey et al., 1973), a 12,000-dalton protein coded for by a gene on chromosome 15 (Good-fellow et al., 1975). HLA-DR molecules on the surface of B-lymphoid cells and monocytes consist of two noncovalently associated glycoproteins with approximate molecular weights of 35,000 and 27,000 (Cress-well and Geier, 1975; Springer et al., 1977). Which of these molecules is the true product of the HLA-DR gene is not absolutely certain; conflicting evidence suggests that both the isolated 27,000-dalton and the 35,000-dalton molecule can bind alloantibodies to HLA-DR following denaturation and separation (Tosi et al., 1978; Klareskog et al., 1978).