Histological and immunohistochemical studies on the role of ?-Lipoic acid on cyclophosphamide-induced immunosuppressive effect in mice

Cyclophosphamide (CP) is an efficient anticancer drug, has been widely used for the treatment of various neoplastic diseases. ?-Lipoic acid (?-LA) functions as an antioxidant in both its reduced and oxidized form. Therefore, the present work was done to investigate the possible protective effect of ?-LA against CP-induced injury in the immune system of mice. To achieve such a purpose, mice were divided into five groups (each of 10 mice) according to their approximately equal mean body weights as following: positive control mice were injected i.p with 0.5 ml saline solution, 3 times/week, for 6 weeks. Positive control mice were administered daily, orally by gavage with 0.5 ml sunflower oil, for 6 weeks. Mice were injected i.p. with 0.6 mg/kg bw/mouse CP, three times/week for 6 weeks. Mice were daily administered orally by gavage with 0.5 ml ?- LA in a concentration of 0.1 mg/kg bw, for 6 weeks. Mice were administered with the same doses of both CP and ?-LA at the same manner and for the same period as in the previous groups. Estimation of rate of mortality, body weight change and the lymphoid organs weights (spleen and thymus) were evaluated. Also, assessment of T- lymphocyte proliferative and T-cell function, using Con A-mitogen as well as immunohistochemical detection of CD3 as a pan T cell marker present on the mature T lymphocytes were estimated. Also, histopathological alterations in spleen and thymus tissues and evaluating the possible ameliorative effect of ?- LA were investigated. The results revealed that in CP-treated mice, different symptoms of toxicity including reduced activity, general weakness were observed, and there was an increase in the rate of mice mortality and significant decrease in the body weights. Also, no significant decreases in the relative spleen weights were detected; however, the relative thymus weights were significantly decreased. The histological observations in spleen of CP-treated mice revealed severe histopathological changes which include: disorganized structure, increased size of the lymphoid follicles, marked depletion in lymphocyte population, and the increase in the number of megakaryocytes. All these pathological alterations were markedly decreased in spleen sections of CP + ?-LA- treated mice. In sections of thymus, CP was found to cause massive depletion in the thymocyte population, decrease in the number of the reticular cells and macrophages, and an increase in the number of Hassall's corpuscles. However, ?-LA could partly reverse the changes induced by CP in thymic tissue. The immunohistochemical detection of CD3 in spleen sections of CP-treated mice, revealed very weak reaction. However, moderate staining reaction was found in the splenic follicles of CP+ ?-LA-treated mice, indicating that ?-LA. In thymus tissues, very weak staining reaction was observed in the different thymic sections of CP-treated mice, however, moderate staining reaction was observed in most areas of thymus in CP+?-LA-treated mice. Hence, the current study proved the protective effect of ?-Lipoic acid on the immunosuppressive effect of CP in male mice, even if it was not a complete protection.