摘要目的 探讨全身照射(TBI)预处理诱导大鼠肝移植术后急性排斥反应的发生机制,及CD4~+ CD25~+调节性T细胞的变化在诱导免疫耐受中的作用.方法 以雄性Lewis、DA大鼠为供、受体,随机分为正常对照组、同种肝移植组、自发免疫耐受组、急性排斥反应组.观察各组受体的生存时间及生存率,检测受体术后外周血中ALT、TB含量、Foxp3~+ CD4~+ CD25~+ 调节性T细胞和T细胞亚群上GITR的表达,检测受体术后第14天移植肝的病理变化和受体脾脏CTL杀伤活性.结果 自发免疫耐受组,术后经历短暂排斥反应最终获得免疫耐受并长期存活.急性排斥反应组,在术后第17～21天死亡,与其他组相比,外周血血清中ALT、TB含量明显升高,而Foxp3~+ CD4~+ CD25~+调节性T细胞比例明显降低.TBI预处理大鼠供肝致受体外周血中CD3~+ CD4~+ T细胞上GITR表达降低,CD3~+CD8~+T细胞上GITR表达增加,提高CTL的杀伤活性.结论 通过TBI清除供体大鼠肝移植物中携带的旁路淋巴细胞,致受体外周血中Foxp3~+ CD4~+ CD25~+调节性T细胞表达降低,而使CD3~+ CD8~+T细胞上GITR表达增加,共同诱导大鼠肝移植术后急性排斥反应发生和耐受障碍.

abstractsObjective To study the effect of total body irradiation of the donor in a spontaneous tolerance rat liver transplantation model and the role of CD4~+ CD25~+ regulatory T cells on induction of immunotolerance in the recipient.Methods Liver transplantation was performed using male Lewis rats as donors and male DA rats as recipients.These rata were randomly allocated into the following groups:Control group,Homogeneity Liver Transplantation group,Idio-immunotolerance group and Acute Rejection group.After transplantation,survival time rate of each group were observed.Serum ALT,TB level,Foxp3~+ CD4~+ CD25~+ regulatory T cells,expression of GITR on T cell subgroup,histopathology of the hepatic graft on day 14,spleen CTL lytic activity on day 14 were measured.Results In the ldio-immnunotolerance group,the recipients suffered from transient rejection after surgery but acquired immunotolerance and survived long.In the Acute Rejection group,the donors were preconditioned with total body irradiation before liver transplantation.All recipients died between day 17 to 21.Serum ALT and TB increased significantly and the ratio of Foxp3~+ CD4~+ CD25~+ regulatory T cells decreased significantly compared with the Idioimmunotolerance group,the Homogeneity Liver Transplantation group and the Control group.The expression of GITR on CD3~+ CD4~+ T cells in the peripheral blood decreased.the expression of GITR on CD3~+ CD8~+ T cells and CTL lytic activity of the recipients increased by preconditioning of the donors with total body irradiation.Conclusions Preconditioning of the donors with total body irradiation eliminated the passenger lymphocytes of the liver graft,decreased the expression of Foxp3~+ CD4~+ CD25~+ regulatory T cells in peripheral blood,and increased the expression of GITR on CD3~+ CD8~+ T cells,thus affected the course of tolerance and induced acute rejection after liver transplantation.