抗人CD3单链抗体/p53四聚功能域融合基因的构建及表达

目的：构建抗人CD3单链抗体(scFv)／p53四聚功能域融合基因，并进行真核表达及活性测定。方法：在已经构建抗人CD3 scFv和人IgG3上游铰链区／p53四聚功能域融合基因基础上，将抗人CD3 scFv克隆入载体pUC18／IgG3／p53中，构建抗人CD3 scFv／p53四聚功能域融合基因。经酶切鉴定及序列测定证实后，将融合基因克隆入真核表达载体pSecTag2-B中，并转染Hela细胞进行表达。表达产物纯化后，利用流式细胞仪进行活性测定。结果：获得了抗人CD3 scFv／p53四聚功能域融合基因，基因全长为882 bp，可编码294个氨基酸，与已发表的抗人CD3 scFv、人IgG3上游铰链区和人p53四聚功能域基因cDNA序列相一致。表达产物经SDS-PAGE和Western blot证实，为Mr约35000的特异蛋白条带。纯化后经流式细胞仪检测，可特异性地结合人外周血单个核细胞(PBMC)，亲和力高于scFv。结论：获得了可与PBMc特异性结合的抗人CD3 scFv四聚体，为进一步临床应用奠定了基础。

Construction and expression of anti-human CD3 single chain Fv antibody/human p53 tetramerization domain fusion gene

AIM: To construct anti-human CD3 single chain Fv antibody (scFv)/human p53 tetramerization domain fusion gene and express the fusion protein in Hela cells. METHODS: The anti-human CD3 scFv was cloned into the previously constructed plasmid pUC18/IgG3/p53 to construct anti-human CD3 scFv /human p53 tetramerization domain fusion gene. After enzyme digestion analysis and sequencing, the fusion gene was subcloned into the expression plasmid pSecTag2-B. Then the plasmid pSecTag2-B containing the fusion gene was transfected into Hela cells. The expressed products were analyzed by SDS-PAGE and Western blot. The binding of the purified fusion protein to human peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. RESULTS: DNA sequencing showed the fusion gene was constructed successfully. The expressed product of the fusion gene with a relative molecular mass (M r) about 35 000 was confirmed by SDS-PAGE and Western blot. The purified tetrameric anti-human CD3 scFv showed significantly stronger binding to PBMCs than scFv. CONCLUSION: The tetrameric anti-human CD3 scFv which can bind to PBMCs has been successfully expressed and purified for potential use in clinical studies.