The generation of lipid peroxides by stimulated human neutrophils. Detection using phenol red oxidation.

When activated, phagocytic cells undergo a burst of oxidative metabolism, consuming oxygen and converting it to several products including superoxide anion and hydrogen peroxide. The latter may be quantified using an assay based on the oxidation of phenol red catalysed by horseradish peroxidase. This method has been employed to evaluate peroxide formation by human neutrophils activated in vitro with a variety of stimuli. Evidence is presented to show that neutrophils secrete different major peroxides depending upon the stimulus, its concentration and the incubation time. Based on inhibition studies using enzymes and drugs these may be identified as hydrogen peroxide and a lipoxygenase product, probably 5-hydroperoxyeicosatetraenoic acid (5-HPETE). Thus, phenol red oxidation may, under certain circumstances, represent a simple assay of lipoxygenase activity in stimulated human neutrophils.