DNA fragmentation induced in lymphocytes by gamma irradiation or dexamethasone: inhibition by diethyldithiocarbamate (DTC), potentiated by zinc.

Apoptosis is a process of physiological cell death characterized by DNA fragmentation, chromatin condensation, loss of membrane asymmetry and cell lethality. In the present study, apoptosis induced in thymocytes by dexamethasone or gamma irradiation is evaluated by flow cytometry, gel electrophoresis and other techniques. Treatment of thymocytes with DTC or zinc shows that these products can inhibit radiation- or dexamethasone-induced apoptosis. Moreover, a synergistic effect is observed by using associations of both products (5 microM DTC + 50 microM ZnSO4): ZnSO4 potentiates the effect of DTC at concentrations for which the molecules used separately show a low efficacy. These results indicate that DNA fragmentation induced by dexamethasone or irradiation in thymocytes share some identical mechanisms.