IL4R and graft versus host disease: We also found that this separation of GVHD from GVL was not dependent on the development of IMP T cells since T cells from IL-4 receptor-alpha and ITK-double knockout mice (Itk/Il4ra DKO), which lack the IMP phenotype (13), did not induce GVHD, Instead, the presence or absence of ITK separated GVHD from GVL in a cell-intrinsic manner.