IL4 and acute graft versus host disease: Historically, acute GVHD has been considered a primarily Th1/Tc1-type process based on the predominant of cytotoxic T-cell mediated pathology and increased production of Th1 type cytokines, including IL-12 and IFNγ, while cytokines that polarize donor T-cells to Th2 (e.g., IL-4, IL-10) can reduce acute GVHD [33], [34], [35].