Influence of steroids on oxidant generation in activated human granulocytes and mononuclear leukocytes

Steroids, in particular, 17beta-estradiol (E(2)), have been reported to improve the response to trauma in animal models. In these models, the leukocyte plays a critical role in the inflammatory cascade. We examined the affects of E(2), hydrocortisone (H), progesterone (P(4)), and E(2) with P(4) on oxidant production in human granulocytes (PMNs) and mononuclear leukocytes (MNCs). Each cell type was loaded with 2,7-dichlorodihydrofluorescein and then simultaneously activated with human cytokines (tumor necrosis factor alpha, interleukin-1beta, and interferon gamma) and hemoglobin and inhibited with and without equimolar concentrations of each steroid treatment or nitric oxide (NO) synthesis inhibitors. After incubations of 1 or 5 h, intracellular oxidants were quantified by flow cytometry. Activation by cytokines combined with hemoglobin, resulted in a 450-575% increase in oxidant production that was synergistically greater than the sum of either component alone. Pharmacological levels of E(2) decreased oxidants in MNCs at 1 h. In contrast at 5 h, H decreased oxidants more than E(2). The addition of P(4) to E(2) concentrations almost eliminated oxidants from 1 h-activated MNCs. None of the steroids significantly reduced oxidants in PMNs, suggesting that the E(2) effect on MNCs was not caused by its nonreceptor-mediated antioxidant properties. Because L-NMMA inhibited at least 55% of the total oxidants, part of E(2) dampening effects would be attributed to NO. These results suggest that steroid-attenuated MNC-derived NO may reduce autocrine and paracrine effects on inflammation if appropriate doses of steroids are given soon after injury.