CD4 and graft versus host disease: The potential role of donor BM-derived CD4 and CD8 T cells in regulation of DLI T cell alloresponses was assessed by comparing GVHD development among WT MCs, RagKO MCs, and MCs that were prepared by injection of syngeneic plus CD4KO (CD4KO MCs) or CD8KO (CD8KO MCs) allogeneic BMCs.