外周血T细胞亚群与大鼠原位肝移植排斥反应的关系

Relationship between T-lymphocyte subsets in peripheral blood and acute rejection after liver transplantation in rats

目的:观察大鼠肝移植术后外周血CD4+/CD8+T细胞亚群比例的变化,探讨其与移植后免疫排斥反应的关系.方法:近郊系大鼠随机分为同基因肝移植组I组(Isograft组:Lewis→Lewis),异基因肝移植组A组(Allograft组:DA→Lewis),每组12对大鼠,另设12只假手术Lewis大鼠作为正常对照(C组).假手术组仅打开腹腔后即缝合,大鼠原位肝移植模型的建立采用改良"二袖套法".观察术后1、2wk存活率,移植肝病理组织学改变和受体外周血CD4+/CD8+T细胞亚群比例的变化.病理检查采用HE染色,外周血CD4+/CD8+T细胞亚群比例的变化采用流式细胞术检测.结果:I组和A组1wk存活率分别是100.0%和41.7%,2wk存活率分别是75%和8.3%(P<0.05).术后7d,A组移植肝均呈现严重急性排斥反应表现,而I组移植肝未发现明显急性排斥反应改变.术后7d流式细胞术检测结果显示:A组外周血CD4+T细胞亚群比例最高,与I组比较差异有统计学意义(P<0.05);CD8+T细胞亚群比例3组中I组最低,I组与C组、A组比较差异均有统计学意义(P<0.05);CD4+/CD8+T细胞比值A组最高,A组与I、C组比较差异均有统计学意义(P<0.05).A组外周血中γ-干扰素(interferon-γ,IFN-γ)水平最高、白介素-10(interleukin-10,IL-10)水平最低,与I、C组比较差异均有统计学意义(P<0.05).结论:外周血CD4+/CD8+T细胞亚群的动态平衡与大鼠肝移植免疫排斥反应及免疫耐受的发生均密切相关,CD4+T细胞增生活跃及CD4+/CD8+T细胞比值升高诱发急性排斥反应,CD8+T细胞分化减少可能是免疫耐受发生的机制之一.

AIM:To investigate the changes of CD4+/CD8+T-lymphocyte subsets in peripheral blood in rats after liver transplantation, and to evaluate their effect on acute rejection.METHODS:Inbred DA and Lewis rats were randomly divided into three groups:a liver isograft group(group I:Lewis → Lewis, n=12), a liverallograft group(A group:DA → Lewis,n=12), and a sham-operated group(group C:Lewis rats, n = 12).Modified 'two-cuff technique' was used to perform rat orthotopic liver transplantation.Survival rates at 1 and 2 wk were computed.Histological changes of graft and the changes of CD4+/CD8+ T-lymphocyte subsets in peripheral blood after transplantation were examined by HE staining and flow cytometry, respectively.RESULTS:One-week survival rates in group I and group A were 100% and 41.7%, respectively.Two-week survival rates were 75% and 8.3%, respectively(P<0.05).Group A showed severe acute graft rejection 7 d after transplantation, but this did not occur in group I.The percentage of CD4+ T cells was significantly higher in group A than in group I and group C(P < 0.05).The percentage of CD8+ Tcells was significantly lower in group I than in group A(P < 0.05).The ratio of CD4+/CD8+ Tcells was significantly higher in group A than in group I and group C(P < 0.05).Serum levels of interferon-γ(IFN-γ) were markedly increased in group A, but decreased in groups I and C, while interleukin-10(IL-10) showed an opposite trend.CONCLUSION:The changes of CD4+/CD8+T-lymphocyte subsets in peripheral blood are closely related to rejection and tolerance after rat liver transplantation.CD4+ T cell proliferative activity and the ratio of CD4+/CD8+ T cells induce acute rejection, and CD8+ T cell reduction may be one of the mechanisms of immune tolerance.