Immunosuppressive Effects of Emodin: An In Vivo and In Vitro Study

Objective: We sought to investigate the immunosuppressive effects of emodin and its potential in vivo and in vitro mechanisms. Methods: In vitro immunosuppressive effects of emodin were analyzed by its ability to suppress the response of human peripheral blood mononuclear cells to phytohemagglutinin (PHA) and to mixed lymphocyte culture (MLC). We examined changes in interleukin (IL)-2 and IL-4 in within MLC supernates. The in vivo immunosuppressive effects of emodin were analyzed using a skin transplantation model in mice. We also investigated the mean survival time (MST) and plasma IL-2 levels. Results: In vitro experiments: Responses of mononuclear cells to PHA and MLC were suppressed by emodin treatment. Decreased production of IL-2 along with promoted secretion of IL-4 was also observed by emodin treatment during MLC. In vivo experiments: The emodin-treated group showed prolonged MST of skin grafts and decreased serum IL-2 production. Conclusions: Emodin showed immunosuppressive activities both in vivo and in vitro. The potential immunosuppressive mechanism of emodin's may be suppression of lymphocyte proliferation and influences on cytokines.