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Interferon-gamma activates human neutrophil oxygen metabolism and exocytosis
M A Cassatella1, R Cappelli, V Della Bianca
1Institute of General Pathology, University of Verona, Italy.
Abstract:
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.
Insights
Recombinant interferon-gamma (rIFN-gamma) enhances human neutrophil functions, including hydrogen peroxide production and granule secretion. This modulation of neutrophil (PMN) activity by rIFN-gamma occurs through protein synthesis-dependent pathways.
Area of Science:
- Immunology
- Cell Biology
Background:
- Neutrophils (PMN) are critical immune cells involved in pathogen clearance.
- Interferon-gamma (IFN-gamma) is a cytokine with known immunomodulatory functions.
Purpose of the Study:
- To investigate the effects of recombinant interferon-gamma (rIFN-gamma) on human neutrophil (PMN) functions.
- To elucidate the mechanisms underlying rIFN-gamma-mediated modulation of PMN activity.
Main Methods:
- Human neutrophils were incubated with varying concentrations of rIFN-gamma.
- Neutrophil functions, including hydrogen peroxide production and granule secretion, were measured in response to various stimuli.
- Inhibitors of protein synthesis and signaling pathways were used to probe mechanisms.
Main Results:
- rIFN-gamma significantly enhanced hydrogen peroxide production and granule secretion in PMNs.
- The effects were dose-dependent and required prolonged incubation.
- Inhibition studies indicated that the enhancing effects of rIFN-gamma depend on de novo protein synthesis.
Conclusions:
- rIFN-gamma effectively modulates human neutrophil functions, enhancing their oxidative burst and secretory responses.
- The observed effects are mediated through pathways requiring protein synthesis, suggesting transcriptional or translational regulation.