腺病毒介导CTLA4Ig基因修饰的骨髓基质细胞诱导特异性免疫耐受的实验研究

Experimental study of BMSCs modified by adenovirus to express CTLA4Ig to induce specific immune tolerance

目的 通过腺病毒介导CTLA4Ig在骨髓基质细胞 (bonemarrowstromalcells ,BMSCs)中的表达 ,探讨CTLA4Ig体外诱导特异性免疫耐受的机制 ,为该基因修饰的BMSCs联合造血干细胞移植 (hematopoieticstemcelltransplantation ,HSCT) ,达到预防移植物抗宿主病 (graft versus hostdisease ,GVHD)和纠正预处理损伤的造血微环境 (hematopoieticinductivemicroenvironment,HIM)积累实验依据。方法 以CTLA4Ig 重组腺病毒按感染复数 (mutiplicityofinfection ,MOI) 5 0转染BMSCs,利用亲和层析的方法纯化培养上清中的目的蛋白CTLA4Ig ,加入到混合淋巴细胞反应 (mixedlymphocytereaction ,MLR)体系中 ,通过MTT显色观察其抑制淋巴细胞增殖的生物学效应 ,以ELISA检测体系中IL 2的水平。结果 纯化的CTLA4Ig对MLR反应体系中淋巴细胞的增殖有明显的抑制作用 ,且在一定范围内与CTLA4Ig的浓度呈依赖性关系 ;体系中IL 2水平与淋巴细胞数有相似的变化趋势 ,且成正相关 (γ =0 85 2 2 ) ;CTLA4Ig组的淋巴细胞数与IL 2水平与对照组相差显著 (P <0 0 5 )。结论 转染后BMSCs表达的目的蛋白CTLA4Ig能有效阻断B7/CD2 8共刺激信号途径 ,从而抑制T细胞活化 ,抑制IL

Objective To investigate the possibility of BMSCs,which was genetically modified by adenovirus to express CTLA4Ig to induce antigen specific T cells immune tolerance,search for the molecular mechanisms related with immune tolerance, and observe the possibility of the modified BMSCs to enhance hematopoiesis.Methods The culture BMSCs were transfected by recombinant adenovirus encoding CTLA4Ig cDNA(AdCTLA4Ig)(MOI=50).The biological activity of purified CTLA4Ig was test by mixed lymphocyte reaction(MLR) through MTT, followed by IL 2 quantitation with ELISA in the MLR system.Results MLR tested that CTLA4Ig had significant inhibition on lymphocyte proliferation.Morever, the inhibition effect was concentration dependent within a certain range.The change of IL 2 level in the MLR system had a similar tendency.Morever, the level of IL 2 was correlated with the number of lymphocyte positively(r=0 8522).Compared with the control group, the transfected groups had significant differences in IL 2 level and the number of lymphocyte( P <0 05).Conclusion The B7/CD28 pathway could be blocked by the expressed CTLA4Ig, which leaded to inhibit T cell activation, proliferation and IL 2 excretion.