Proton release by polymorphonuclear leukocytes during phagocytosis or activation by digitonin or fluoride

The stimulation of polymorphonuclear leukocytes with bacteria or digitonin causes protons to be released into the reaction medium at the same time as the respiratory burst. Although lactic acid is released from the cells due to the stimulated metabolic activity, proton release was not due to lactic acid accumulation as fluoride markedly inhibited lactic acid accumulation in untreated cells within 5 minutes of incubation and a rapid proton release and superoxide anion production occurred after lactate production had ceased. The proton releasing mechanism, however, is closely linked with the activation of the plasma membrane NAD(P)H oxidase since the proton release is depressed only when the activation mechanism and/or the oxidase is inhibited.