Inhibition of autologous mixed lymphocyte reaction by monoclonal antibodies specific for the β chain of HLA-DR antigens.

Recent studies using rabbit antisera to the separated HLA-DR α and β subunits have suggested that α chain-specific, but not β chain-specific, antisera inhibit T cell proliferative responses in primary and secondary human autologous mixed lymphocyte reaction (AMLR). In the present study, with the aid of sequential co-precipitation assays and Western blotting methods, a monoclonal rat alloantibody 1E4, specific for the β chain of rat class II molecules carrying an Ia determinant Ba-2.7, was characterized to recognize a monomorphic determinant located on the β chain of DR antigens. This antibody and a murine monoclonal antibody HU-4, also specific for the β chain of DR antigens, strongly inhibited both primary and secondary AMLR through a mechanism distinct from an antibody-dependent cell-mediated cytotoxicity reaction. These results indicate that the inhibition of AMLR is not a unique feature of DR α-specific antibodies. [ABSTRACT FROM AUTHOR]