Exploratory strategies that suppress GVHD while preserving the GVT effect comprise the induction of the T helper-2 (Th2) pathway [4]; the latter includes the cytokine interleukin-4 (IL4), proteins of IL4 receptor (IL4R) complex such as IL4Rα chain or the transcription factor STAT6. This evidence concerns the gene STAT6 and graft versus host disease.