Objective To investigate the relationship of acute graft versus host disease (aGVHD) and the regulatory T (Treg) cells,NK cells as well as their function-related cytokines such as IL-10,TGF-β,and perforin in mice with allogeneic bone marrow transplantation.Methods H-2 completely mismatched C57BL/6→ BALB/c aGVHD mice model was constructed.Flow cytometry analysis was used to detect the proportion of CD4+CD25 + Treg cells and NK-1.1+ NK cells in the spleen of aGVHD mice after transplantation.ELISA method was used to detect the serum levels of IL-10,TGF-β and perforin in the aGVHD mice intervened with CSA prophylactic or not.The normal C57BL/6 mice were used as controls.Results Compared with those of normal mice,the proportion of Treg cells in aGVHD mice after transplantation was decreased (mean 3.6％ vs.1.55％) and the proportion of NK cells increased (mean 3.3％ vs.11.5％).In the aGVHD mice treated with cyclosporine A,serum IL-10 expression level was significantly increased (treated group (125.79 ± 0.27)pg/mL,untreated group [(103.09 ± 3.27)pg/mL,P＜0.01)],TGF-β expression level was increased [(252.05 ±7.84)pg/mL vs.(241.61±15.41)pg/mL,P＞0.05],perforin expression level was significantly increased [(186.97 ± 4.68)pg/mL vs.(144.35 ± 14.42)pg/mL,P＜0.01].Conclusion ① The occurrence of aGVHD is correlated with the decreased number of Tree cells after transplantation in mice.Treg cell function-related cytokines IL-10 and TGF-β are involved in the treatment of aGVHD by cyclosporine A-mediated immunosuppression.②NK cells are involved in the occurrence of aGVHD after allogeneic bone marrow transplantation,and the increased level of perforin is related to the inhibition of aGVHD.