TF and graft versus host disease: STAT5, another critical TF in Th2 differentiation, was found to have a dual role in Th2 and Treg differentiation in GVHD, as overexpression of STAT5 led to increased Treg numbers and attenuated GVHD, while in the absence of Tregs, anti-inflammatory Th2-cytokines increased (108).