IGHE and graft versus host disease: Although MCs were previously recognized as a driver of the pathology of GVHD, which was supported by a GVHD model study using KitW-sh/W-sh mice as recipients [81] and by a study evaluating the effect of blocking the interaction between IgE and FcεRI in GVHD [82], an opposite role of MCs was also found in GVHD [83].