IL17A and graft versus host disease: Moreover, the expression of proinflammatory cytokine (IL-6, IL-17 and TNF-α) decreased, and that of Foxp3 increased, in the GVHD target tissues (skin, liver, lung, and intestine) from mice treated with MDSC and Treg, suggesting that the in vivo suppressive activity of the combination therapy is attributable in part to soluble mediators.