Background: Treatment with interferon-gamma (IFN-gamma), a key mediator for adequate forward-regulatory monocyte immune capability, has been advocated to overcome posttraumatic mononuclear leukocyte paralysis. Conversely, IFN-gamma also is a potent proinflammatory mediator contributing to capillary leakage in sepsis-driven organ failure. The objective of this investigation was to further define the potential of IFN-gamma as a modifier of monocyte activity before and after injury.
Methods: Whole blood samples from 19 patients (7 female and 12 male patients; age, 68 +/- 5 years) before and after cardiac surgery with extracorporeal circulation were incubated under continuous rotation with lipopolysaccharide for 12 hours in the presence or absence of human recombinant IFN-gamma. Pro- and anti-inflammatory cytokines were determined in the plasma.
Results: Lipopolysaccharide-induced release of tumor necrosis factor-alpha, interleukin (IL)-6, IL-12, and IL-1Ra, and prostaglandin E2 was clearly augmented with IFN-gamma most strikingly postoperatively (p < 0.05). There was no effect on IL-1beta, neopterin, and soluble tumor necrosis factor-R release.
Conclusion: Thus there is a wide spectrum of IFN-gamma activity on monocyte activation including anti-inflammatory properties. Since cellular preactivation facilitates monocyte reactivity toward IFN-gamma, we conclude that exogenous administration should be effective but must be carried out with great caution in patients with profound inflammation.