THE EARLY INTRACELLULAR PRODUCTION OF A REACTIVE OXYGEN INTERMEDIATE MEDIATES APOPTOSIS IN DEXAMETHASONE-TREATED THYMOCYTES

Many conditions that induce an oxidative stress are capable of evoking apoptosis, This has lead to the proposal of oxidative stress as a med iator of apoptosis. We show that, in murine thymocytes, oxidative stre ss and apoptosis occur in the same cell,We identified four distinct ap optotic subpopulations that appeared sequentially in time, Catalase pr otected from dexamethasone-induced death in the initial stages of apop tosis, while iron chelators and Vitamin E did not. Further studies pro vided evidence supporting the early production of an intracellular oxi dative intermediate as an obligatory step for the efficient induction of apoptosis, We propose that at least one of the molecules capable of filling this role is hydrogen peroxide.