Cytotoxic drug-induced p53 expression and activation of CD95 in resting versus cycling PHA-stimulated T cells.

(A) Cytotoxic drug-induced death in resting and stimulated CD4 T cells. Unstimulated PBLs (open symbols) and lymphocytes stimulated for 72 hours with PHA and IL-2 (closed symbols) were cultured in medium, 10 μg/mL cytarabine (triangles), and 10 μg/mL etoposide (squares) for 6, 12, and 18 hours. Cells were analyzed by flow cytometry for CD3, CD4, CD45RO, and annexin V binding. Cytotoxic drug-specific cell death was calculated from the proportion of annexin-positive cells of CD4⁺CD45RO⁺ T lymphocytes in the treated and untreated samples. Bars represent the standard deviation of the experiment performed in triplicate. Results from a representative experiment of 3 independently performed experiments are shown. (B) Cytotoxic drug-induced protein expression of p53 and CD95 ligand. PBLs and stimulated lymphocytes were cultured in medium, 10 μg/mL cytarabine, and 10 μg/mL etoposide as in panel A. CD95 ligand and p53 were detected by immunoblot at 18 hours for unstimulated lymphocytes and at 6 hours for stimulated lymphocytes.