Many agents which induce apoptosis are either oxidants or stimulators of cellular oxidative metabolism. Conversely, many inhibitvrs of apoptosis have antioxidant activities or enhance cellular antioxidant defenses. Mammalian cells exist in a state of oxidative siege in which survival requires an appropriate balance of oxidants and antioxidants. Thomas Buttke and Paul Sandstrom suggest that eukaryotic cells may'benefit from this perilous existence by invoking oxidative stress as a common mediator of apoptgsis.

Apoptosis is a morphologically distinct form of cell death that is ievolved in many physiological and pathological processes/. Because apoptosis is an integral part of the developmental program, and is frequently the end-result of a temporal course of cellular events, it is sometimes referred to as programmed ceil death (PCD). The intense interest of immunologists in apoptosis stems from its apparent involvement in thymic selection, cell-mediated cytotoxicity, activation-induced death altd the pathogenesis of acquired immune deficiency syndrome (AIDS). The widespread occurrence of apoptosis has provoked efforts aimed at defining the cellular regulatory mechanisms and biochemical processes involved; such knowledge may lead to new therapeutic approache~ for treating malignancies, autoimmune diseases and AIDS. While there is considerable variation in the signals and requisite cellular metabolic events necessary to induce apoptosis in diverse cell types, the morphological features associated with apoptosis are highly conserved. This may imply the coexistence of multiple signalling pathways that converge upstream of a common sequence of events which nltirnately cldrnin~ te in~ nnn-