Phorbol myristate acetate-induced neutrophil autotoxicity

We have previously shown that in the presence of phorbol myristate acetate (PMA), neutrophils kill neoplastic cells as well as themselves. This PMA-induced neutrophil autotoxicity was markedly inhibited by catalase, suggesting that H₂O₂ directly or indirectly played an important role. In this study we compared PMA and H₂O₂ toxicity against human neutrophils. The effect of H₂O₂ was faster and more sensitive to catalase and serum than that of PMA. Sodium azide markedly enhanced the effect of H₂O₂ but not that of PMA. In contrast, methionine and histidine prevented the toxicity of PMA, while they had no effect on H₂O₂ toxicity. The results suggest that PMA-induced neutrophil autotoxicity is not mediated by H₂O₂ alone.