In lethally-irradiated full donor chimeras, it was found that depletion of recipient T cells prior to DLI promotes GVHD, and that the exacerbation of GVHD in this model was due to removing CD4+CD8− and CD4−CD8−, but not CD8+, Tregs [8], [14]. This evidence concerns the gene CD8A and graft versus host disease.