IFNG and graft versus host disease: Without in vitro “PMA+I” stimulation, the CD4+IFN-γ+ Th1 and CD4+IL-4+ Th2 cells could be easily detected in peripheral blood of patients who had GVHD, indicates the intracellular IFN-γ and IL-4 were abundant in the T helper subsets during period of GVHD.