Role of neutrophils in release of some cytokines and their soluble receptors.

Available data suggest that cytokines and soluble cytokine receptors, which are being produced by immunological cells, can modulate the immune response of the host. Although the production of mediators such as TNF-alpha and IL-6 as well as that of their soluble receptors has been extensively studied in tissue cells and mononuclear cells, it has not been fully investigated in neutrophils (PMN). In the present study we examined the ability of PMN to simultaneously release TNF-alpha, IL-6 and their soluble receptors-sTNFRp55, sTNFRp75 and sIL-6R. Concentrations of soluble receptors were compared with expression of membrane-bound TNF and IL-6 receptors. For comparative purposes, similar examinations with autologous peripheral blood mononuclear cells (PBMC) were performed. We found that PMN and PBMC have the same ability to release IL-6 and sTNFRp75. In contrast, there were significant differences in the release of TNF-alpha, sTNFRp55 and sIL-6R between these cells. Reduction in membrane TNF receptor expression, observed in this study, was associated with increase secretion of soluble TNF receptors by PMN and PBMC. The results suggest that PMN can play an essential role in modulating the inflammatory response by affecting the balance between pro-inflammatory mediators, such as TNF-alpha, and anti-inflammatory mediators, such as soluble TNF receptors.