Suppression of T-cell activation in vitro and in vivo by cordycepin from Cordyceps militaris

Abstract

BackgroundIn addition to achieving a balance between the positive (controlling rejection) and the negative (infection and malignancy) aspects of drug-induced immunodeficiency, new immunosuppressive combinations must address the issue of nonimmune drug toxicity that may be dose limiting. Cordycepin is a type of adenosine analog extracted from Cordyceps militaris. In the present study, we investigated its immunosuppressive effect on T cell both in vitro and in vivo. MethodsWe evaluated the effects of cordycepin on concanavalin A–induced production of immune mediators in mouse splenocyte by enzyme-linked immunosorbent assay and flow cytometry. Furthermore, using Western blotting, we studied signal transduction mechanisms to determine how cordycepin inhibited T-cell activation in purified mouse T lymphocytes. To confirm the immunosuppressive activity of cordycepin in vivo, we induced the T cell–mediated delayed-type hypersensitivity reaction in a 2,4-dinitro-1-fluorobenzene–induced mouse model. ResultsThe in vitro results showed that cordycepin markedly suppressed concanavalin A–induced splenocyte proliferation, Th1 and Th2 cytokine production, and the ratio of CD4+-to-CD8+ T cells. The administration of cordycepin in vivo markedly suppressed the T cell–mediated delayed-type hypersensitivity reaction. The data revealed that cordycepin effectively shocked the nuclear factor kappa B and nuclear factor of activated T cells 2 signal transduction pathways but had no effect on the mitogen activated protein kinase signal transduction pathway. ConclusionsThese observations indicated that cordycepin has a potential role in downregulating the immune system and could be developed as a useful immunosuppressive agent for treating undesired immune responses.