Effect of IFN-γ + IL-7 on Fas expression in thymic subsets. Thymocytes were first labeled with anti-Fas, then with biotin-coupled antimouse antibody, and lastly with Quantum Red-conjugated streptavidine and anti-CD4 and anti-CD8 antibodies; only the last two steps were performed for staining controls. (A) Data are the means ± SEM of 5 experiments. IFN-γ + IL-7 increased the Fas^hi thymocyte proportion in all the thymic subsets (CD4⁺, CD4⁺CD8⁺, and CD8⁺ cells). *P < .05 versus control. (□) Medium; (⊟) IL-7 + IFN-γ. (B) Representative analysis of the proportion of Fas^hi thymocytes and MFI of Fas staining in each culture condition and thymic subset. Fas staining is shown as solid profiles and staining controls as open profiles.