Interferon Gamma Modulates the Expression of Neutrophil-derived Chemokines

Specific cell recruitment to a site of acute inflammation is a crucial event characterized by the elicitation of mainly polymorphonuclear neutrophils (PMNs). Recently, it has been reported that PMNs can express and secrete chemotactic cytokines or chemokines, including IL-8, MIP-1 alpha, and MIP-1 beta. Moreover, PMN-derived chemokines are regulated by various soluble mediators, such as dexamethasone, prostaglandin E, classic chemoattractant factors (e.g., fMLP, C5a, leukotriene B4), IL-4, and IL-10. In this article we demonstrate that PMNs treated with IFN-gamma, a Th1-derived cytokine, can inhibit early mRNA expression for MIP-1 alpha, MIP-1 beta, and IL-8 (up to 8 hours post IFN-gamma addition), while augmenting their production at 24 hours post IFN-gamma addition. Furthermore, our studies demonstrate that one of the mechanisms for the activity of IFN-gamma in this system is via the autocrine activity of TNF-alpha. These data imply that PMN-derived chemokines are regulated by not only proinflammatory cytokines, including IL-1 beta and TNF-alpha, but also Th1- and Th2-derived cytokines, including IL-4, IL-10, and IFN-gamma. The role of these cytokine networks in regulating PMN-derived chemokines may play an important role in leukocyte elicitation during the initiation and maintenance of an inflammatory response.