The immunotoxicity mediated by cyclophosphamide (CYP) was earlier reported. Quercetin, due to its anti-oxidative/inflammatory properties elicits a plethora of health benefits. However, the influence of quercetin on the splenic/immunotoxicity linked with CYP-induced indoleamine 2,3-dioxygenase (IDO) is unavailable in the literature. We investigated the effects of quercetin on the splenic immunosuppressive IDO and hematological indices of immune response in rats. Animals were treated with CYP (100 mg/kg) alone or co-treated (CYP + quercetin [100 mg/kg + 50 mg/kg respectively]) at days 1, 3, 5, and 7. Results revealed that CYP treatment alone significantly provoked an oxidative-inflammatory response, increased serum kynurenine concentration, and concomitantly increased immunosuppressive IDO and tryptophan 2, 3-dioxygenase (TDO), in the spleen as well as altering hematological indices. Quercetin co-treatment enhanced activities of antioxidant enzymes, inhibited myeloperoxidase (MPO) activity, lowered levels of nitric oxide, interferon-Υ (IFN-Υ), and interleukin-6 (IL-6), and reduced kynurenine concentration as well as IDO/TDO activities. Quercetin co-treatment augmented white blood cell (WBC), CD4-T cells, and other hematological indices of the immune response. In conclusion, quercetin prevented CYP-induced alterations in immune response in rats by lowering the activities of immunosuppressive IDO and TDO, inhibiting oxidative-inflammatory stress, diminution of kynurenine concentrations, and augmenting hematological parameters.
Keywords: 3-dioxygenase; 3-dioxygenase1; Hematology; Indoeamine 2; Inflammatory stress; Oxidative stress; Spleen; Tryptophan 2.
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