In an attempt to reduce the risk of graft-versus-host disease (GVHD) and Epstein-Barr virus-related lymphoproliferative disease, Federmann et al. used CD3/CD19-depleted grafts with RIC and observed that T cell reconstitution after haplo-SCT was delayed with a median of 205 CD3+ cells/μL, 70 CD3+ CD4+ cells/ul, and 66 CD3+ CD8+ cells/μL on day 100, respectively [14]. This evidence concerns the gene CD4 and graft versus host disease.