“…The main manifestation of GVHD is the immune attack to multiple organs, with the gastrointestinal tract, lungs, liver, and skin being the preferential targets. 2 Although not usually described with the classic symptoms, marrow suppression with compromised hematopoiesis and poor immune reconstitution has long been appreciated in clinical GVHD. The cause of this phenomenon has not been carefully studied and up until now, it was not known whether this was the product of destruction of hematopoietic progenitors or an indirect effect of damage to the bone marrow microenvironment.…”