Human Ia Antigens -- Purification and Molecular Structure

The major human histocompatibility complex, HL-A, contains many genes which especially control the expression of cell-surface antigenic determinants, immune-response (Ir) differences, certain complement functions, and probably other functions related to cell-cell recognition (Bodmer 1972; Crumpton and Snary 1977). Among the gene products is a new set of polymorphic serological specificities called Ia (immune-associated) antigens which are expressed on B lymphocytes, but only in trace amounts or not at all on T lymphocytes, and which appear to be the analogs of the mouse Ia antigens (work from various laboratories presented in Histocompatibility Testing 1975 [Kissmeyer-Nielsen 1975]). These antigens probably represent the products of several loci (Mann et al. 1976), some of which show a close association with the HL-A D locus that controls the expression of the major antigenic determinants involved in mixed lymphocyte responses (Bodmer et al. 1976). The D-locus determinants have also been linked genetically to an individual's susceptibility...