Effects of caspase inhibition. (A) Purified B-CLL cells from 8 different samples were cultured for 72 hours with 1000 ng/mL BL22 in the presence or absence of 100 μM Z-VAD.fmk. Apoptosis induction was determined by Annexin V staining as described in “Patients, materials, and methods.” Results are presented as means ± SEM. (B) TUNEL staining was performed in 3 different samples cultured with either BL22 ± Z-VAD.fmk or, as a control, medium without supplementation. Shown is a representative experiment. Similar results were obtained in 2 additional experiments.