title: Monoclonal anti-Lyt-2 antibodies block the activation of cytolytic T lymphocyte precursors.
abstract: In the present study, we reinvestigated the effects of anti-Lyt-2 monoclonal antibodies (mAb) on the generation of H-2K/D-specific Lyt-2+ cytolytic T lymphocytes (CTL). A sensitive limiting dilution microculture system supplemented with a source of interleukin 2 (IL 2) was employed to provide a minimal estimation of the frequency of CTL precursors (CTL-P) in normal spleen or mixed leukocyte culture (MLC) populations. The addition of anti-Lyt-2 (but not anti-Thy-1) mAb at culture initiation caused an average 78% reduction in the number of CTL-P within spleen cell populations that were activated by allogeneic stimulation. Most CTL that were generated from Lyt-2+ CTL-P in the presence of anti-Lyt-2 mAb were not inhibited in cytolysis by such mAb, whereas the majority of CTL generated in the absence of anti-Lyt-2 were inhibitable. In contrast to normal spleen, the frequency of (operationally defined) CTL-P that had been activated for 5 days in primary MLC was unaffected by the presence of anti-Lyt-2 mAb. Collectively, these results demonstrate that anti-Lyt-2 mAb are capable of inhibiting the antigen-dependent activation of normal splenic precursors of Lyt-2+ CTL. The fact that IL 2 could not overcome the inhibition suggests that anti-Lyt-2 mAb may have affected the expression of IL 2 receptors as a direct consequence of inhibiting CTL-P antigen recognition.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology*; D001667:Binding, Competitive; D002452:Cell Count; D003602:Cytotoxicity, Immunologic; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology; D007518:Isoantibodies / Q000502:physiology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D051381:Rats; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007518:Isoantibodies; C029805:Lyt antibodies