Inhibition of T cell-mediated cytolysis by monoclonal antibodies directed against Lyt-2: heterogeneity of inhibition at the clonal level.
The inhibitory effect of monoclonal anti-Lyt-2 antibodies on T cell-mediated cytolysis has been investigated at the clonal level. In agreement with previous reports from several laboratories, populations of cytolytic T lymphocytes (CTL) generated in vitro in mixed leukocyte cultures (MLC) were reversibly inhibited by monoclonal anti-Lyt-2 antibodies in a dose-dependent fashion. However, when alloimmune peritoneal exudate lymphocytes (PEL) were used as a source of CTL, little or no inhibitory effect of anti-Lyt-2 antibodies on cytolysis was observed. A series of CTL clones derived from MLC or PEL populations was also tested for inhibition of cytolysis by anti-Lyt-2 antibodies. In agreement with results obtained at the population level, most MLC-derived clones (81%) were strongly inhibited by the reagent, whereas few PEL clones (15%) were inhibited. Several of these clones were expanded and maintained in culture without loss of their "inhibition phenotype." Flow cytofluorometric analysis using the same monoclonal anti-Lyt-2 antibodies further revealed that both inhibited and uninhibited clones expressed comparable amounts of Lyt-2 antigen. These results provide direct evidence that inhibition of CTL by anti-Lyt-2 antibodies is heterogeneous at the clonal level. The possibility that this heterogeneity may be related to avidity of antigen receptors is discussed.
D000818:Animals; D000906:Antibodies; D000941:Antigens / Q000276:immunology*; D001202:Ascitic Fluid / Q000166:cytology; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D013601:T-Lymphocytes / Q000276:immunology*
D000906:Antibodies; D000941:Antigens