TRERF1 and graft versus host disease: Thus, the strong effect of Rapa in augmenting the IL-2-mediated conversion of Tconvs into iTregs could have contributed more to protection against GVHD in the study by Shin et al. Nevertheless, even in the presence of nTregs, our data support a beneficial effect in combining Rapa and IL-2 in the treatment of GVHD.