Nucleoside-induced DNA damage of B-CLL cells.

(A) B-CLL cells from 4 different patients were treated at the indicated time points with 10 μmol/L of 2CdA, CaFdA, F-Ara-A, and dAdo. DNA damage by alkaline unwinding was assessed. Data are reported as percentage ds-DNA. (B) Single-cell DNA damage (comet assay) was performed after 6-hour treatment with 10-μmol/L concentrations of the drugs. Cells were plated on a slide in low-melting point agarose and lysed, and current was applied for 10 minutes at 1 V/cm. At least 100 cells were counted, and the percentages of the comets were determined. Columns represent the mean and error bars the standard deviation obtained from 4 patients. (*) Statistically increased from control untreated cells; P < .05 by the nonparametric Mann-Whitney test. (C) Example of comets after treatment with F-Ara-A compared to control cells. These data were obtained from a single patient and are representative for 4 patients.