Among them, IL-7 and IL-15 have been reported to promote the induction and expansion of the human memory stem cell-like T cell subset, described as CD95+CD45RA+CD45RO+CD62L+CCR7+IL-7Rα+, that was able to engraft, expand and mediate enhanced activity in a xenogeneic transplant model of graft versus host disease (GVHD) [13]. Here, IL15 is linked to graft versus host disease.