title: Monoclonal antibodies to HLA-DP, DQ, and DR determinants: functional effects on the activation and proliferation of normal and EBV-transformed B cells.
abstract: To investigate the function of HLA class II molecules in B-cell activation, we generated three new anti-HLA class II monoclonal antibodies with differing specificities for DP, DQ, and DR determinants. These were tested for their ability to inhibit various B- and T-lymphocyte responses. Each of these antibodies (NB-29, DH-84, and DH-224) immunoprecipitates a heterodimer of approximately 35,000 and 28,000 mol wt from 125I-surface-labeled B-lymphoma cells, as shown by SDS-PAGE. NB-29 (IgG1) detects a polymorphic DQ determinant, while DH-224 (IgG1) is reactive with monomorphic DR determinants, and DH-84 (IgG2a) has specificity for DP, DQ, and DR. Both DH-224 and DH-84, but not NB-29, were found to inhibit significantly the stimulation of peripheral blood mononuclear cells (PBMC) by anti-mu (70%-90% inhibition) and by lipopolysaccharide (80%-90% inhibition), as measured by incorporation of tritiated thymidine. When added to highly purified populations of peripheral blood B cells, none of these anti-class II monoclonal antibodies inhibited anti-mu-induced stimulation. This suggests that the inhibitory effect that DH-224 and DH-84 have on the stimulation of unfractionated PBMC may be due to their ability to interfere with the action of accessory cells. Epstein-Barr-virus (EBV)-transformed B-cell lines, in contrast, showed substantial inhibition of growth when cultured in the presence of any of the three antibodies. With respect to T cells, DH-84 and DH-224 strongly inhibited the mixed lymphocyte response; NB-29 did not. None of these antibodies inhibited stimulation of PBMC by phytohemagglutinin (PHA). These findings suggest that DQ and DR HLA class II molecules have differing roles in B-cell activation and document a direct antiproliferative effect of anti-HLA class II monoclonal antibodies on the growth of EBV-transformed cell lines.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002472:Cell Transformation, Viral; D000939:Epitopes / Q000032:analysis*; D006681:HLA-D Antigens / Q000276:immunology*; D006682:HLA-DP Antigens / Q000276:immunology*; D006683:HLA-DQ Antigens / Q000276:immunology*; D006684:HLA-DR Antigens / Q000276:immunology*; D004854:Herpesvirus 4, Human; D006801:Humans; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D009000:Monocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006681:HLA-D Antigens; D006682:HLA-DP Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens