Delayed sequential mouse allogeneic-bone marrow transplantation attenuating graft-versus-host disease

Abstract

Objective To explore the effect and mechanism of delayed sequential mouse allogeneic-bone marrow transplantation (BMT) attenuating acute graft-versus-host disease (aGVHD).Methods BALB/c (H-2d) mice were used as recipients,and C57BL/6(H-2b) mice as donors.The model of BMT was established after recipients accepting total body irradiation (TBI) of 60Co γ ray.Five experimental groups were set up:control group,4 h after TBI,recipients were infused via tail vein with 0.4 m1 RPMI 1640 liquid;glassic group,4 h after TBI,recipients were infused with bone marrow cells (BMC) and spleen cells (SC) 1×107 per 0.2 ml liquid respectively;sequential group,at 4 h,1 day,2 day and 3 day after TBI,BMC and SC (2.5×106 per 0.05 ml liquid each) were infused via tail vein respectively;Delayed group:at day 4 after TBI,BMC and SC(2.5×106 per 0.05 ml liquid each) were infused via tail vein respectively:Delayed sequential group,at day 4,5,6 and 7 after TBI,BMC and SC(2.5×106 per 0.05 mlliquid each) were infused via tail vein respectively.The clinical manifestation,pathologic changes and survival rate of recipients were observed after transplantation.The serum levels of cytokines of the recipients including IL-2,IL-4,IL-10 and IFN-γ were detected by ELISA,and the percentage of H-2b cells,T lymphocyte subpopulation and NK cells was measured by flow cytometry.Results Recipients in control and classic groups all died of hemopoiesis failure and/or aGVHD within 3 weeks after transplantation.The 60-day survival rate in sequential and delayed groups was 30% and 50% respectively,but in the delayed sequential group,the 60-day survival rate was 70%,which was significantly higher than in other groups (P＜0.05).The expression levels of IL-4 and IL-10 in the delayed sequential group were significantly higher than in the classic group,while the expression levels of IL-2 and IFN-γ were on the contrary (P＜0.05).In the delayed sequential group,he percentage of H-2b cells was (98.13±1.11)% on the day 60,WBC counts reached the normal value on the day 20 and the subpopulation of T lymphocytes and NK cells reached the normal value on the day 30.Conclusions The machanism by which the delayed sequential transplantation can attenuate aGVHD is contributed to the fact that it escapes from the peak expression of inflammatory factors after TBI,meanwhile reduces the expression of inflammatory factors and type 1 cytokines of T lymphocytes but increasing the expression of type 2 cytokines. Key words: Bone marrow transplantation; Graft versus host disease; Mice