Regulation of cytokine production by eicosanoids and nitric oxide.

Cytokines are widely regarded as regulatory molecules of inflammatory and immune reactions. Nevertheless, the details of functioning of the complex cytokine network are not yet fully understood. Recent data indicate that eicosanoids, primarily the products of the inducible form of cyclooxygenase (COX-2), are involved in the regulation of cytokine production. We have shown that prostaglandins of E series are no longer only suppressor molecules but they selectively up- or down-regulate the cytokine production. Similarly, nitric oxide (NO) generated in activated immune cells by inducible isoform of nitric oxide synthase (iNOS), is considered to be an immunoregulatory molecule. In this article we present a new concept of interactions between cytokines, eicosanoids (prostaglandins and leukotrienes) and NO. Finally, the impact of these molecules on the regulation of the immune system is discussed.