OX40 regulates T cell survival and Bcl-2 and Bcl-xL.

(A–D) Fas, Annexin V and active caspase 3 analyses were performed to detect apoptotic signals in co-transferred TCRtg cells (WT red, OX40−/− black) and endogenous CD4 and CD8 T cells (grey area) after LCMV cl13 infection. (A, B) Representative Annexin V stainings and bar graphs showing Annexin V MFI on CD4 smtg cells on day 8 p.i. (A) and on CD8 P14 cells on day 10 p.i. (B). (C) Representative Fas staining on day 8 p.i. and bar graph showing Fas expression 5, 8, and 20 days post infection on CD4 smtg cells. (D) Representative intracellular staining for active caspase 3 and bar graph showing Caspase 3 MFI on day 8 p.i. on CD4 smtg cells. Data are derived from 3 independent CD4 smtg cell transfer experiments and one CD8 P14 transfer experiment. (E) Analysis of expression of anti-apoptotic molecules Bcl-2 and Bcl-xL on virus-specific CD4 T cells of WT and OX40−/− mice (WT red, OX40−/− black) via intracellular protein staining 8 and 20 days post persistent LCMV infection. Data are derived from 1–2 independent experiments per time point.