Inhibition of leukotriene B4(LTB4) by recombinant interleukin-1 receptor antagonist (IL-1RA) on human monocytes.

Macrophages are a primary source of interleukin-1 (IL-1), a glycoprotein which plays an important and essential role in the immune response and inflammation. Cytokines stimulate many different cells to produce increasing amounts of arachidonic acid metabolites such as prostaglandins and leukotrienes. Recently, interleukin-1 receptor antagonist (IL-1ra), a natural inhibitor of IL-1 released by macrophages, has been reported to inhibit PGE2. In accordance with these data our results show that the pretreatment, for 60 min, of purified human peripheral monocytes with IL-1ra at different concentrations (0.25-250 ng/ml) inhibits, in a dose-dependent manner, the generation of LTB4 released after 10 min treatment with calcium ionophore A23187 (5 microM). The inhibition of LTB4 synthesis by hrIL-1ra suggests the possibility that this new glycoprotein plays a modulatory role in immunity and inflammation.