供者凋亡细胞静脉输注在异种肝移植中所产生体液免疫机理

Humoral immunity induced at liver xenotransplantation by intravenous infusion of donor′s apoptotic cells

目的以贵州香猪为供者、中国猕猴为受体的异种肝移植模型，采用静脉输注异种异基因骨髓及凋亡细胞的方法预处理受体，研究凋亡细胞对异种肝脏移植免疫排斥反应的影响，探讨异种肝脏移植免疫耐受的机制。方法受者猕猴随机分为A、B、C组，A组为阴性对照组，n=6；B组为实验对照组，n=28，在接受RIC之后，再接受供者贵州香猪的异种异基因骨髓（BM）静脉输注；C组为实验组，n=36，在接受RIC之后，再接受供者贵州香猪的BM和凋亡细胞同时静脉输注。观察各组受体的生存期，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术后第14天受体脾脏CTL杀伤活性。结果C组肝移植术后经历短暂排斥反应，最终可获免疫耐受并长期存活，其外周血中Foxp3＋CD4＋CD25＋调节性T细胞表达比例在术后第14天渐恢复正常，受体外周血中cB3十CD4＋T细胞上GITR表达降低，CD3＋C晚＋T细胞上GITR表达增加，提高CTL的杀伤活性；B组受体在术后第17～21天死亡，与A、C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。结论供者凋亡细胞静脉输注在异种肝移植中所产生体液免疫耐受的机理，可能是通过诱导受体外周血中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的杀伤活性来实现的。

Objective To research the effects and mechanism of immunologic rejection and tolerance in xenotransplantation of the liver, the model was made by Guizhou Xiang pig as donor and china monkey as receptor. Then, the models were pretreated by intravenous infusion of allo- geneic bone marrow and apoptotic cells. Methods Recipient monkeys were divided into A, B, C group randomly. Group A（ n = 6） was the negative control group, group B（ n = 28） the experimen- tal control group, which were injected by intravenous infusion mr the Guizhou Xiang pig allogeneic bone marrow （BM） after RIC. And group c（ n = 28） was the experimental group, which were in- jected with BM and apoptotic cells after RIC. The receptor＇s survival was observed. The contents of ALT and TB in peripheral blood were determined . The expression of Foxp 3 ＋ CD4 ＋ CD25 ＋ inRegulatory T Cells and GITR in T lymphocyte subpopulations were also measured . At the 1 4 th day, the pathological change of transplantation Liver and CTL activity in spleen were investigated. Results After the liver transplantation, the group e under went acute rejection, and acquired the immunologic tolerance and longterm survival at last. And at the 14 th day, the expression rate of Foxp3 ＋ CD4 ＋ CD25 ＋ in Regulatory T Cells in peripheral blood returned to normal. GITR expression in CD3 ＋ CD4 ＋ T cells decreased, and increased in CD3 ＋ CD8 ＋ T ceils. The killing activity of CTL was improved. The group B was dead during 17--21 days after surgical operation. Compared with group A, C, the contents of ALT and TB in peripheral blood in group B increased, but the rate of Foxp3 ＋ CD4 ＋ CD25 ＋ Regulatory T Cells decreased. Conclusions The mechanism of humoral immune in xenotransplantation of the liver by intravenous infusion of donor＇s apoptotic cells may be induced by decreased GITR expression in CD3 ＋ CD4 ＋ T cells and increased in CD3 ＋ CD8 ＋ T cells, which can improve killing activity of CTL in receptor.