Free radicals in immunological killing: the case of tumor necrotising factor (TNF).

There is now considerable evidence that in many circumstances free radical activity constitutes not only an early but also an essential event in the causation of cell death in vivo. It is proposed that the cytotoxic effect of TNF against tumours may be exerted in like manner, by stimulating the generation of hydroxyl radicals which leads in turn to an upset of energy metabolism, and hence to cell death. Simple experimental protocols are indicated for testing the proposal at various stages.