APOPTOSIS INDUCTION WITH 3 NUCLEOSIDE ANALOGS ON FRESHLY ISOLATED B-CHRONIC LYMPHOCYTIC-LEUKEMIA CELLS

The cytotoxic effects and the induction of programmed cell death (apop tosis) by Fludarabine (FLU), 2-chlorodeoxyadenosine (2-CdA), and deoxy coformycin (DCF) with/without alpha-interferon (alpha-IFN) were evalua ted in vitro against freshly isolated B-chronic lymphocytic leukemia ( B-CLL) cells. Cytotoxicity was evaluated according to the soluble tetr azolium/formazan assay. Regarding the cytotoxicity, FLU, 2-CdA, and DC F showed a mean antitumor activity of 45% +/- 3.39 (mean +/- S.D.), 55 % +/- 4.72, and 20% +/- 3.16, respectively. alpha-IFN alone showed a m ean cytotoxic activity of 10% +/- 2.72. The cytotoxicity of these puri ne analogues in combination with alpha-IFN was 52% +/- 2.97, 75% +/- 3 .41, and 26% +/- 7.09, respectively. We observed a statistically signi ficant increase of cytotoxicity compared to controls in FLU atone (P < 0.05), 2-CdA (P < 0.05), and their combination with alpha-IFN (P < 0. 05). Apoptosis was evaluated by electrophoresis gel of DNA oligonucleo somal fragments and by a cytofluorimetric method. Only FLU and 2-CdA a ctivated the apoptosis and DCF showed a minor apoptotic pathway amount . These apoptosis data were confirmed by both gel electrophoresis of D NA and by propidium iodide cytofluorimetric method. FLU and 2-CdA show activity in B-CLL cells by direct cytotoxic action and the induction of cell death by apoptosis; in the future, it would be interesting to utilize these in vitro assays in monitoring chemosensitivity and predi cting response for the clinical use. (C) 1994 Wiley-Llss, Inc.