Characterization of a monoclonal anti-beta 2-microglobulin antibody and its use in the genetic and biochemical analysis of major histocompatibility antigens.

A monoclonal anti-beta 2-microglobulin (BBM.1 antibody) was produced by cell fusion between the mouse myeloma, P3-X63-Ag8, and spleen cells from a BALB/c mouse immunized with Molt 4, a human T cell line. BBM.1 antibody was fully inhibited by soluble beta 2-microglobulin and purified HLA-A, B antigens and reacted with human-mouse somatic cell hybrids only if they had chromosome 15 and expressed human beta 2-microglobulin. It was cytotoxic in complement-dependent lysis and of the IgG class. BBM.1 and a monoclonal anti-HLA-A, B, C glycoprotein antibody, W6/32 (Barnstable, C. J. et al., Cell 1978. 14:9.), were used to quantitate relative amounts of beta 2-microglobulin and HLA-A, B, C glycoproteins on different human cell types. Thymocytes and the Molt 4 cell line showed a considerable excess of beta 2-microglobulin over HLA-A, B, C glycoproteins, as measured by W6/32 reactivity. B cell lines, peripheral blood lymphocytes, fibroblasts, a HeLa cell derivative, and HSB2, another T cell line, had equal amounts. Immunological cross-reactions between HLA-A, B, C antigens and beta 2-microglobulin and their homologues in other species were detected with the BBM.1 and W6/32 antibodies. The W6/32 antigenic determinant appears to be more highly conserved than that recognized by the BBM.1 antibody.