IL6 and graft versus host disease: Consistent with the expansion of immunosuppressive lymphocytes, serum levels of IL-6, IL-17A, IFN-γ, MCP-1, IL-1α and IL-1β are significantly reduced in i35-Breg-treated mice (Figure 2H) indicating that i35-Breg cells might suppress the production of cytokine storms implicated in GVHD pathology.