Forodesine-induced cell death in primary CLL cells. (A) Cells from 1 representative patient with CLL were treated for 48 hours with forodesine (2, 5, or 10 μM) and dGuo (10, 20, or 30 μM). Cell death was analyzed by annexin V binding. (B) Primary cells from 50 patients with CLL and CD3⁺ cells or CD19⁺ cells from PBMCs of 4 healthy donors were incubated with 2 μM forodesine and dGuo (10-20 μM), and cell death was analyzed by annexin V binding at 24 and 48 hours. Mean cytotoxicities are given as the percentage of the apoptotic cells with respect to the viability of control cells. Data are given as the mean ± SD. (C) Cell death of forodesine 2 μM and dGuo 20 μM after 48 hours of incubation considering the expression levels of ZAP-70 or CD38. The cutoff point for high expression levels of ZAP-70 was 20% or greater and 30% or greater for CD38.^3,4  (D) Forodesine 2 μM and dGuo 20 μM cell death at 48 hours in primary CLL cells regarding cytogenetic alterations. Black bars show the mean of cell death induced of each group.