DNA FRAGMENTATION INDUCED IN LYMPHOCYTES BY GAMMA-IRRADIATION OR DEXAMETHASONE - INHIBITION BY DIETHYLDITHIOCARBAMATE (DTC), POTENTIATED BYZINC

Apoptosis is a process of physiological cell death characterized by DN A fragmentation, chromatin condensation, loss of membrane asymmetry an d cell lethality. In the present study, apoptosis induced in thymocyte s by dexamethasone or gamma irradiation is evaluated by flow cytometry , gel electrophoresis and other techniques. Treatment of thymocytes wi th DTC or zinc shows that these products can inhibit radiation- or dex amethasone-induced apoptosis. Moreover, a synergistic effect is observ ed by using associations of both products (5 mu M DTC + 10 mu M ZnSO4 or 1 mu M DTC + 50 mu M ZnSO4): ZnSO4 potentiates the effect of DTC at concentrations for which the molecules used separately show a low eff icacy. These results indicate that DNA fragmentation induced by dexame thasone or irradiation in thymocytes share some identical mechanisms.