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 mono-nuclear 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.