Caspase activation by in vivo chemotherapy.

(A) Peripheral blood mononuclear cells from patients undergoing chemotherapy were isolated at different times of treatment as indicated. Caspase-8, caspase-3, and PARP were detected by immunoblot. Arrows indicate the intermediate forms of caspase-8 p43 and p41 and the active subunit p18 in the caspase-8 immunoblot. In the caspase-3 immunoblot, the active subunits p17 and p10 are indicated, whereas in the PARP assay, cleaved PARP at 85 kd is marked by the arrow. (B) Effect of caspase inhibition on spontaneous in vitro apoptosis of CD4 T cells during chemotherapy. Peripheral blood mononuclear cells were isolated at the indicated time of treatment. After cultivation for 24 hours in complete medium (filled circles) or in medium with 50 μM caspase inhibitor Z-VAD (open circles), cells were analyzed by flow cytometry for CD4 and annexin V binding. Bars represent the error of the experiment performed in triplicate. Shown are the results of 3 of 7 representative experiments.