造血细胞嵌合体供者诱导异种移植物的免疫耐受☆

Mechanisms of surrogate tolerogenesis for xenotransplantation induced by chimeric donor with mononuclear cells derived from cord blood

目的:探讨脐血造血细胞嵌合体动物作为异种组织、器官移植的供者,诱导异种移植物免疫耐受的机制。方法:实验于2005-06/2006-01在解放军第一五九中心医院全军烧伤中心实验室完成。①采用人脐血单个核细胞经宫内胎鼠移植加新生鼠肝内注射的方法制作人脐血造血细胞嵌合体动物模型,非嵌合体对照以同法注入等量磷酸盐缓冲液。②4周后利用免疫组织化学和流式细胞三色标记检测嵌合体大鼠体内人源性细胞和补体调节蛋白,并对hCD45/SSC设门时不同区域内hCD55和hCD59阳性细胞的百分率进行分析。③用补体依赖性淋巴细胞毒性反应评估嵌合体鼠异种移植免疫适应性,与非嵌合体鼠进行比较;并对嵌合体鼠补体依赖性淋巴细胞毒性反应和外周血补体调节蛋白地相关关系进行分析。结果:①随机选择嵌合体大鼠14只,非嵌合体大鼠8只进行研究。②嵌合体鼠骨髓、脾脏和心脏中有人源性β2微球蛋白阳性细胞和hCD55,hCD59抗原存在,外周血中hCD45+细胞的比率为(6.69±4.51)%。选择hCD45/SSC设门时,hCD45+细胞区域中hCD55和hCD59阳性细胞占门内细胞数的(53.69±18.23)%和(31.8±27.5)%,占全细胞总数的(2.0±1.32)%和(0.74±0.59)%,与全细胞区域内hCD55和hCD59阳性细胞百分率犤(4.11±2.83)%和(2.82±1.38)%犦相比,差异具有显著性意义(t=-2.7～-3.7,P<0.05)。③嵌合体组补体依赖性淋巴细胞毒性反应显著低于非嵌合体组犤(20.85±15.03)%,(60.70±21.08)%,t=-3.924,P<0.01犦。④嵌合体大鼠的淋巴细胞毒试验结果与外周血hCD55+细胞百分率呈负相关(r2=0.637,P<0.05)。结论:人脐血造血细胞嵌合体大鼠的骨髓、外周血、脾脏和心脏有人源性细胞分布,嵌合体内异种补体调节蛋白的存在,可能是造血细胞嵌合体供者异种移植物免疫耐受的基础。

AIM： To explore the mechanism of surrogate tolerogenesis for xenotransplantation induced by the chimeric donors With mononuclear cells derived from cord blood. METHODS： The experiment was conducted in the Laboratory of Military Burn Center, the 159 Hospital of Chinese PLA from June 2005 to January 2006. ①Mononuclear cells from human cord blood were transplanted into fetal rats in uteri and infused into the livers of neonatal rats to establish the chimeric animal models, meanwhile, the control rats were treated with phosphate buffer solution by the same method. ②Four weeks later, humanderived cells, human complement regulatory protein （hCD55 and hCD59） were detected by immunohistochemistry and three-colour labelling flow cytometry, and the percentages of hCD55 and hCD59 antigens were analysed on CD45/SSC gating. ③The resistance of peripheral blood lymphocytes （PBLs） to cytolysis in chimeric rats was assessed with complement-dependent cytotoxicity （CDC） to compare with the non-chimeric rats. RESULTS： ①Fourteen chimeric rats and eight non-chimeric rats were randomly selected for research. ②Human β2-microglobulin positive cells, hCD55 and hCD59 antigens were found in the bone morrows, spleens and hearts of the chimeric rats, the percentages of hCD45%＋ cells in chimeric rats was （6.69±4.51）%. On hCD45/SSC gating, the＇proportions of hCD55^＋ and hCD59^＋ cells in hCD45^＋ cells region were （53.69±18.23）% and （31.8 ±27.5）%, accounted for （2.0±1.32）% and （0.74±0.59）% of total cell population, which had significant difference compared with the percentages in total cell region [（4.11±2.83）% and （2.82±1.38）%; t=-2.7, P 〈 0.05; t=-3.7, P 〈 0.05]. ③The cytolysis rate of PBLs incubated with normal human serum in chimeric rats was significant lower than that in non-chimeric rats [（20.85±15.03）%, （60.7±21.08）%, t=-3.924, P 〈 0.01l. ④The cytolysis rate in CDC was negatively correlated with the percentage of hCD55^＋ cells within peripheral blood （r^=0.637, P 〈 0.05）. CONCLUSION： Cells derived from human cord blood distribute at the bone morrows, peripheral blood, spleens and hearts of the chimeric rats. The presence of xeno-CD55 and CD59 antigens in chimeric donors may be the basis of surrogate tolerogenesis for xenotransplantation.