Since in previous work with CD4+ and CD8+ Tregs induced ex vivo the CD8+ Tregs were major contributors to the protection of immunodeficient mice from human anti-mouse GvHD through non-cytotoxic suppressive effects on allogeneic cells (24), we suggest that the CD8+ Tregs in our current study did contribute to the protective effects on the human anti-mouse GvHD. This evidence concerns the gene CD4 and graft versus host disease.