title: Evidence for the involvement of HLA-DR antigens in restricted cytotoxicity by fetal calf serum-specific human T cells.
abstract: Fetal calf serum (FCS) generated at least two distinct populations of human cytotoxic cells in vitro. One population expressed natural killer (NK) cell-like activity and lysed K562 and HSB-2 targets more effectively than autologous or allogeneic lymphoblastoid cell lines (LCLs). The other population contained FCS-specific cytotoxic T cells which preferentially lysed the autologous LCLs and showed minimal lysis of K562. E-rosette separation and cold target competition experiments clearly established that NK cells were not involved in the self-reactive lysis. Moreover, the lytic activity of the E-rosetted T cells was reduced by up to 95% when autologous target cells were grown in human AB serum rather than FCS, showing that FCS-associated determinants on targets were essential in the cytolytic phase. Autologous LCLs grown in FCS were also considerably stronger competitors than human serum-grown LCLs. The consistent self-preferred lysis suggested that HLA antigen-related restriction was involved, but the patterns of lysis did not implicate HLA-A or B antigens, and monoclonal antibody (W6/32) to an A, B, and C monomorphic determinant failed to block FCS-specific lysis. In contrast, monoclonal antibody (DA.2) to a monomorphic determinant of DR effectively blocked FCS-specific lysis. Cytotoxicity tests with a small panel of DR-typed donors indicated that strong cross-reactions were invariably associated with sharing of DR antigens, particularly DR2, and to a lesser but significant extent DR7. Although DR antigen sharing did not always result in lysis of allogeneic targets, the overall evidence strongly suggests that FCS-specific T-cell cytotoxicity in humans is restricted by products encoded by or associated with the DR genes.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001667:Binding, Competitive; D002417:Cattle; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D005312:Fetal Blood / Q000276:immunology*; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II