Equal survival of Fas-costimulated and control-stimulated T cells after in vivo transfer.

Following activation under control conditions or Fas ligation, viable cells were purified and equal numbers injected into Rag^−/− recipient mice. (A) A blood sample was drawn 12 days after transfer, and white blood cells were stained for CD4 and Vβ5 using directly fluorochrome-conjugated mAbs and analyzed by flow cytometry. Percentages are indicative of positively stained (phenotype of OT-II T cells) cells in 2 individual mice. (B) At 25 days after transfer, mice were killed and, using the same methods as for panel A, spleen cells were stained and analyzed for the percentage of OT-II T cells (■: mice received control cells; ▪: mice received Fas-costimulated cells). (C) At the same time, spleen cells were placed in culture with ovalbumin (2 mg/mL) in the presence of control (■) or a-Fas (▪) Ab. Proliferation in response to antigen rechallenge was measured during a 72-hour incubation period. (D) Production of IFN-γ was measured from culture supernatants at day 3 using specific ELISA. Results in panels B-C are mean ± SEM of 6 mice per group, and results in panel D are mean ± SEM of 8 mice.