Induction of apoptosis in vivo and in vitro in hairy cell leukemia treatedby deoxycoformycin

The leukemic cells of a patient with hairy cell leukemia were treated in vi tro with 2'-deoxycoformycin (dCF), an inhibitor of adenosine deaminase, and deoxyadenosine (dAdo). Following this treatment, viability of the hairy ce lls progressively declined, and DNA fragmentation was observed. When the pa tient was treated with 4 mg/m(2) dCF intravenously, hairy cells in his peri pheral blood rapidly decreased, and a large number of TUNEL (terminal deoxy nucleotidyl transferase-mediated dUTP- biotin nick end-labeling)-positive c ells mere detected in a bone marrow biopsy specimen. These findings indicat e that dCF induced apoptosis of hairy cells both in vivo and in vitro. Furt hermore, bcl-2 mRNA was down-regulated by dCF and dAdo in the hairy cells i n vitro. Our results suggest the importance of bcl-2 mRNA regulation in apo ptotic cell death mediated by dCF in hairy cell leukemia.