Induction of apoptosis in cells of the immune system by cytotoxic stimuli.

Apoptosis is a physiological mode of death where the dying cell plays an active part in its own demise, which contrasts sharply with what is seen in necrosis. In the present paper I have shown that when cells of the immune system are exposed to a range of cytotoxic agents, such as the RNA synthesis inhibitor actinomycin D, the DNA polymerase inhibitor aphidicolin or the topoisomerase I inhibitor campthothecin, they rapidly undergo cell death via apoptosis. This is characterized by DNA fragmentation to yield the now hallmark ladder pattern of death by this mechanism. All of these agents are capable of inducing apoptosis irrespective of what phase of the cell cycle a cell is in. These studies also indicate that apoptosis can occur in immune cells without recourse to macromolecular synthesis.