Monoclonal antibody definition of multiple polymorphic epitopes on human leukocyte antigen-DRw52

Monoclonal antibodies have revealed complexity within the human leukocyte antigen class II antigens. We have studied epitopes present on a DR3 homozygous B-lymphoblastoid cell line using five polymorphic monoclonal antibodies produced and characterized in our laboratory. Serological analysis on a panel of B-cell lines revealed that the antibodies have different, but related, specificities (NDS9-anti-DR3, NDS10-anti-DR5, less than 3, less than w6, NDS11-anti-DR3, 5, w6, NDS12-anti-DR3, 5, w6, w8, NDS13-anti-DR3, 5, w6, w8+). Competitive radioimmunoassays and two-dimensional gel analyses demonstrated that whereas the epitopes recognized by the broadly reactive antibodies NDS10, 11, 12, and 13 reside on the same molecule, the epitope detected by NDS9 is present on a molecule with different electrophoretic mobility. Thus, using polymorphic monoclonal antibodies, we have defined multiple epitopes associated with DR3, which have different distributions at the population level.