title: Expression of Qat-4 and Qat-5 alloantigens on cytotoxic precursor and effector cells: different surface phenotypes of alloreactive and H-2 restricted cytotoxic T cells.
abstract: Monoclonal anti-Qat-4 and anti-Qat-5 antibodies, which define antigens expressed on peripheral T cell subsets, have been used to study the phenotypes of alloreactive and H-2-restricted cytotoxic effector cells and their precursors. Depletion of Qat-4+ or Qat-5% cells from the T cell pool prior to their sensitization in bulk cultures prevented the development of alloreactive and H-2-restricted cytotoxic activities in the selected populations. No reconstitution of cytolytic activities to normal levels was obtained when mixtures of Qat-4- and Qat-5- cells were sensitized in bulk cultures to H-2 or non-H-2 antigens. Sensitization of limiting numbers of Qat-4- or Qat-5- lymphocytes under optimal conditions for help (interleukin 2), with the appropriated antigens (H-2 or H-Y) did not result in the generation of cytotoxic T cells, indicating that the majority of all cytotoxic T lymphocyte (CTL) precursors are Qat-4+, Qat-5+. When CTL effector populations were treated with the antisera and complement (C) at their maximum CTL activity, it was found that H-2-restricted CTL were totally eliminated by anti-Qat-4 and considerably reduced by anti-Qat-5 antisera and C. In contrast, alloreactive CTL effector cells were insensitive to anti-Qat-4 and to anti-Qat-5 plus C. Although alloreactive CTL effector populations regained some Qat-4 antigens during further in vitro culture, it was shown that H-2-restricted CTL were at all times more sensitive to anti-Qat-4 than were alloreactive CTL. The findings suggest that during maturation of alloreactive and H-2-restricted CTL from their precursors, both alloantigens undergo differential quantitative variations in their expression that lead to different Qat-4,5 phenotypes of alloreactive and H-2-restricted CTL.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000378:metabolism; D003602:Cytotoxicity, Immunologic; D005260:Female; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology*; D007106:Immune Sera / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D010641:Phenotype; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D006183:H-2 Antigens; D007106:Immune Sera; D003165:Complement System Proteins