Stimulation of neutrophil oxidative metabolism by chemotactic peptides: influence of calcium ion concentration and cytochalasin B and comparison with stimulation by phorbol myristate acetate.

Incubation of human neutrophils with the chemotactic peptide F-met-Ieu-phe induced uptake of extracellular oxygen and production of both superoxide anion (02) and chemiluminescence in a concentrationdependent fashion. F-met-met-met also stimulated these cell functions, but it was less potent than F-met-leu-phe. whereas the nonformylated met-met-met had little effect. Pretreatment of neutrophils with cytochalasin B produced a twofold to fivefold increase in 03 release and luminescence and a fourfold to sevenfold increase in the lysosomal enzyme release induced by the peptides. In contrast, the 0 release, chemiluminescence. and enzyme release stimulated by phorbol myristate acetate (PMA) were not significantly affected by the presence of cytochalasin. Addition of calcium ion (Ca 1, but not addition of magnesium ion (Mg 1, to cells in cationfree buffer markedly enhanced the 0 release. chemiluminescence. and oxygen consumption induced by F-met-leu-phe. Ca + + caused no enhancement of the 03 release and luminescence induced by PMA. The enhancement of peptide-stimulated oxidative metabolism by Ca + is compatible with the concept that changes in intracellular Ca + concentrations are involved in activation of the enzyme responsible for the respiratory burst. The peptide concentrations required to stimulate oxidative metabolism were 10-50 times those needed for chemotaxis. Thus, at the origin of a gradient of chemotactic factors (that is, at sites of inflammation), these factors could stimulate production of reactive oxygen metabolites. which might contribute to the tissue damage and perhaps microbicidal activity mediated by neutrophils.