Even more interestingly, the plasma IL-10 was significantly lower in “external control” (patients with no GVHD after transplant) comparing to “internal control” (inactive phase of patients having GVHD), indicates IL-10, while attenuating GVHD in some animal models [30] and ex vivo study [31], is not prerequisite to suppress the development of GVHD in the real world situation. The gene discussed is IL10; the disease is graft versus host disease.