目的  重组表达人MHC Ⅰ类链相关蛋白A α3结构域（MHCⅠchain related protein A α3 domain，MICA-α3）蛋白及自然杀伤细胞受体2D（natural killer group 2D，NKG2D）蛋白，制备抗MICA-α3单克隆抗体，并检测其结合功能。方法  构建MICA-α3及NKG2D蛋白表达载体，经转化大肠埃希菌BL21菌株表达重组蛋白，通过分子筛、组氨酸标签蛋白层析纯化。用重组MICA-α3蛋白免疫小鼠，采用杂交瘤技术筛选单克隆抗体，用细胞ELISA检测单克隆抗体功能。结果  重组蛋白在大肠埃希菌BL21菌株中以包涵体形式表达。筛选得到5株能和表达MICA-α3的MDA-MB-453细胞结合的单克隆抗体,且不影响MDA-MB-453细胞与NKG2D结合。结论  制备的抗MICA-α3单克隆抗体能与肿瘤细胞结合，同时不影响肿瘤细胞与NKG2D结合。

Objective  To express recombinant human MHCⅠchain related protein A α3 domain (MICA-α3) and natural killer group 2D (NKG2D), prepare anti-MICA-α3 monoclonal antibodies and test antibody binding function. Methods  MICA-α3 and NKG2D expression vectors MICA-α3-pET11c and NKG2D-pET16b were constructed and transformed into BL21 for expression. Recombinant proteins were purified by polyhistidine-tag chromatography and gel chromatography. After immunizing mice with MICA-α3 protein and screening monoclonal antibody by hybridoma technology, the monoclonal antibody function was tested by cell-ELISA. Results  Recombinant proteins were expressed in the form of inclusion body in E.coli  BL21. Five monoclonal antibodys were screened, which could bind to MDA-MB-453 cells espressing MICA-α3，and this binding did not affect the binding of MDA-MB-453 cells to NKG2D. Conclusion  Anti MICA-α3 monoclonal antibody can bind to tumor cells without affecting the binding of tumor cells to NKG2D.