Effect of B-PAC-1 treatment on apoptosis in CLL lymphocytes and normal PBMCs and B cells. (A-F) Freshly isolated CLL lymphocytes were treated with the indicated concentrations of B-PAC-1 for 24 hours (n = 26; A); vehicle alone or B-PAC-1 at 2 µM (n = 21; B); 5 µM (n = 28; C); 8 µM (n = 16; D); 10 µM (n = 39; E); or 20 µM (n = 21; F). (G) Comparison of B-PAC-1–induced apoptosis in normal vs malignant cells. Freshly isolated CLL cells and healthy donor PBMCs and B cells (CD19⁺ negatively selected) were treated with the 10 µM B-PAC-1 for 24 hours. Apoptosis was measured by Annexin V/PI staining assay and unstained cells were considered viable cells. □, B cell stained with CD19⁺ using flow cytometry; ▪, isolated CD19⁺ (negatively selected) B cells. For panel A, Annexin V/PI⁻ cells in DMSO control were set as 100% and appropriately cell viability was calculated for B-PAC-1–treated cells. For panels B-F, raw cell death data for DMSO or B-PAC-1–treated cells are presented. For panel G, DMSO cell death was subtracted from the drug-treated value and plotted.