Interferon-gamma activates human neutrophil oxygen metabolism and exocytosis.

Here we have investigated the ability of recombinant interferon-gamma (rIFN-gamma) to modulate human neutrophil (PMN) functions. PMN incubated in the presence of rIFN-gamma showed an enhanced hydrogen peroxide production in response to Con A, FMLP, PMA or immune complexes. The effect of rIFN-gamma was dose dependent, being half maximal at 2 U/ml, and required between 90 min and 240 min of incubation to reach optimal response. The enhancing effect of rIFN-gamma on the respiratory response of PMN was not blocked by polymixin B sulphate, but an anti-rIFN-gamma monoclonal antibody and cycloheximide and actinomycin D were effective inhibitors. The enhancement of the response to Con A was not accompanied by an enhanced binding of the lectin. Neither the kinetic properties of the Con A-stimulated NADPH oxidase nor the expression of cytochrome b-245 were altered in rIFN-gamma-treated PMN. rIFN-gamma also enhanced granule secretion in response to Con A, FMLP and PMA. Initial studies on the possible alterations of transmembrane signalling in rIFN-gamma-treated PMN showed that neither inositol phosphates formation nor cytoplasmic calcium transients were altered.