Effect of cyclosporin A (CsA) on the increase in Fas^hi cell proportion induced by anti-CD3 antibody or by IFN-γ + IL-7. (A) Representative analysis of Fas expression and Fas staining MFI in human thymocytes activated for 24 hours with anti-CD3 antibody or IFN-γ + IL-7 in the presence of cyclosporin A (100 ng/mL). Thymocytes were first labeled with anti-Fas antibody, then with biotin-coupled antimouse antibody, and lastly with Quantum Red-conjugated streptavidine; only the last two steps were used for staining controls. Fas staining is shown as solid profiles and staining controls as open profiles. Cyclosporin A partially inhibited the anti-CD3–induced increase in Fas expression but did not modify the increase in Fas expression induced by IFN-γ + IL-7. (B) Effect of cyclosporin A in the different subsets of human thymocytes cultured with immobilized anti-CD3 antibody. Data are the means ± SEM of 3 experiments. Cyclosporin A partially inhibited the increase in the Fas^hi cell proportion among CD4⁺ and CD4⁺CD8⁺ thymocytes. (□) IgG1; (⊟) anti-CD3; (▪) anti-CD3 + CsA.