Taken together, CD4 Tregs in CD8KO MCs are likely to be functional and therefore, the more severe GVHD in CD8KO MCs than in CD4KO MCs after DLI suggests that the protective effect against GVHD of donor BM-derived T cells is attributed more to donor BM-derived CD8 than CD4 T cells. This evidence concerns the gene CD4 and graft versus host disease.