以DNA免疫和细胞抗原加强制备抗DAF单克隆抗体及特性分析

目的:联合应用DNA免疫和细胞抗原加强制备抗DAF单克隆抗体(mAb)并鉴定其特性。方法:利用分子克隆的方法构建重组质粒pcDNA3.1/DAF。以其免疫BALB/c小鼠股四头肌3次,并在融合前用表达DAF分子的HPB-ALL细胞为抗原加强免疫1次,制备抗DAFmAb。以ELISA法测定mAb的Ig亚类。采用流式细胞术和Westernblot鉴定mAb的特异性和结合活性。以非免疫竞争法测定mAb的亲和常数。结果:成功地获得2株可识别DAF分子不同抗原表位的mAbB6E和2B6B,其Ig亚类均为IgG2a。mAb2B6E的亲和常数为1.81×10-7mol/L,与天然的细胞膜蛋白、变性的膜蛋白以及重组DAF蛋白都有良好的结合活性和特异性。结论:先以pcDNA3.1/DAF肌肉内免疫,再应用细胞抗原加强免疫的方法制备特异性的mAb,为在无法获得纯化蛋白质的情况下开拓了研制特异性抗体的新途径,也为日后改造抗DAFmAb进行靶向治疗研究打下了基础。

Production and property identification of monoclonal antibodies against DAF molecules by DNA immunization followed by a single boost with cell antigen

AIM: To produce mAb against DAF by DNA immunization followed by a single boost with cell antigen and to characterize its property. METHODS: Recombinant plasmid pcDNA3.1/DAF was constructed by molecular cloning technique and injected into mice quadriceps muscle of thigh. To boost the DAF immunized mice, HPB-All cell antigen were injected on day 3 before cell fusion. The affinity and property of mAb to natural membrane protein and denatured protein were identified by FCM, fluorescence microscope and Western blot. RESULTS: Two mAb against DAF were obtained, namely 2B6B and 2B6E. The affinity constant of 2B6E was 1.81x10(-7) mol/L. The isotype of the two mAbs were IgG2a, and the epitope of them was different. FCM, fluorescence microscope and Western blot indicated that the obtained mAb had affinity to natural membrane protein and denatured protein with high specificity. CONCLUSION: This study indicates that the DNA immunization and cell antigen boost method enables mice to produce mAb against DAF. The low frequency of nonspecific mAb is one of the advantages of this method compared to the conventional cell immunization method. Moreover the mAb generated by this method has satisfactory binding activity and specificity.