IL22 and graft versus host disease: However, IL-22-producing T cells were not evaluated in those studies, and although AhR is the critical nuclear factor for regulating IL-22-producing T subsets (48–51), an increase of AhR expression was observed in the SR-Gut-GVHD target tissues of patients (47), and IL-22 from donor T cells were reported to augment Gut-aGVHD in murine model (52, 53).