Serological biochemical and functional characterisation of three different HLA-DR monoclonal antibodies derived from C57BL6 mice.

C57BL6 mice which do not express I-E gene products were immunised with EBV transformed human B cell lines to generate MoAbs. Three hybridoma supernatants which initially reacted with the immunising donor cell but not a T cell line lacking Class II antigens were further investigated. I-D SDS-PAGE patterns of molecules precipitated by the three supernatants from a cell membrane lysate were characteristic of HLA-Class II alpha and beta chains. Two-dimensional analysis established the specificity of the supernatants as HLA-DR specific. This was confirmed by the reaction patterns with Class II mutant deletant cell lines. In both ELISA and cytotoxicity one reacted with all lymphoblastoid cell lines tested, one reacted with all except two that were DR7 homozygous and the third reacted strongly only with cells that were DR3. All three antibodies were cytotoxic to both peripheral blood lymphocytes and EBV transformed B cell lines. The DR3 specific MoAb (IgG2a) was suitable as a typing reagent. The DR3 reactive MoAb specifically inhibited stimulation by a Dw3 HTC and the other two MoAbs inhibited all HTCs tested. These findings are consistent with the view that certain determinants responsible for the Dw specificities are carried on the DR molecules.