Effect of interferon on activated oxygen production in human monocytes in vitro : Direct measurement of phagosomal activated oxygens by a new method using luminol-binding microspheres.

Abstract

We examined the effects of recombinant human interferon (IFN)-gamma, having Met-Gln at the N-terminal, on the in vitro production of phagosomal and extracellular activated oxygen species by human monocytes after phagocytosis and compared the results with those for natural human IFN-alpha and -beta. The phagosomal production was measured by a new method using luminol-binding microspheres and the extracellular production was measured by two conventional methods using luminol sulution and opsonized zymosan or yeast particles. We also examined the effect of the IFN-gamma on the phagocytic activity of human monocytes by using luminol-binding microspheres. It was found that IFN-gamma remarkably augmented both phagosomal and extracellular production of activated oxygen species after phagocytosis in a dose-dependent fashion. However, IFN-alpha and -beta had a weak effect on the phagosomal production only at the highest dose tested. The natural IFNs also augmented moderately or slightly the extracellular production stimulated by opsonized zymosan but not opsonized yeast particles. IFN-gamma augmented the phagocytic activity of human monocytes. THese results demonstrated that the human monocytes treated with the IFN-gamma actually produced a larger quantity of phagosomal activated oxygen species than those treated with the natural IFNs, and the extracellular production did not always reflect the phagosomal production.