Anthracyclines trigger apoptosis of both G(0)-G(1) and cycling peripheral blood lymphocytes and induce massive deletion of mature T and B cells

The anthracyclines daunorubicin and doxorubicin were shown to induce apopto sis of hematopoietic cell lines. Here we report that they induce apoptosis of both nonactivated and phytohemagglutinin-activated human peripheral bloo d lymphocytes. Apoptosis demonstrated by surface expression of phosphatidyl serine and typical nuclear alterations reached a maximum after 48 h of incu bation with these agents. In contrast to topoisomerase inhibitors (etoposid e and camptothecin) and antimetabolites (methotrexate and 5-fluorouracil) t hat induced apoptosis of activated cells only, daunorubicin and doxorubicin triggered apoptosis of cells in the G(0)-G(1) phases of the cell cycle. In agreement with in vitro data, a single i.p, injection of daunorubicin or d oxorubicin in BALB/c mice induced T- and B-cell depletion in spleen, lymph nodes, and to a lesser extent in the thymus, Soluble Fas-Fc, CD95 antagonis tic antibodies, as well as the p55 tumor necrosis factor receptor-immunoglo bulin fusion protein, did not inhibit drug-induced apoptosis, The level of reactive oxygen species was significantly increased in the presence of daun orubicin or doxorubicin only in nonactivated lymphocytes. However, antioxid ants such as N-acetyl-L-cysteine or glutathione did not prevent apoptosis, Activation of caspase-3 after daunorubicin or doxorubicin treatment of eith er nonactivated or activated lymphocytes was demonstrated by the cleavage o f poly(ADP-ribose) polymerase, which was, as apoptosis, inhibited by the pe ptide benzyloxycarbonyl-val-Ala-Asp-fluoromethylketone Finally, daunorubici n and doxorubicin induced a rapid production of ceramides. These data indic ate that anthracyclines may induce major peripheral T-cell deletion, a prop erty not shared by many cytotoxic agents.