人OX40胞外区基因的克隆、原核表达及单克隆抗体的制备

目的制备抗人OX40单克隆抗体,为进一步研究OX40/OX40L通路以及针对该通路进行疾病干预、疾病治疗和药物筛选奠定基础。方法 PCR扩增人OX40胞外区的基因序列,将其构建到原核表达载体pET-32a(+)中,利用大肠杆菌表达系统表达OX40胞外区蛋白,经Ni柱纯化后获得目的蛋白。以纯化的OX40胞外区蛋白为免疫原免疫小鼠,采用常规方法进行细胞融合,通过ELISA和多次克隆化培养,筛选出分泌特异性鼠抗人OX40单克隆抗体的杂交瘤细胞株;通过ELISA、Western blot和免疫荧光检测抗体的效价及特异性。结果成功构建人OX40原核表达质粒pET-32a(+)-OX40,并在BL21(DE3)中诱导表达,经SDS-PAGE和Western blot鉴定、Ni柱纯化、透析后获得OX40胞外区蛋白;以此纯化蛋白为免疫原,成功制备具有较强亲和力的单克隆抗体。结论克隆表达并纯化了人OX40蛋白,成功制备针对该蛋白的高亲和力单克隆抗体,为进一步研究OX40/OX40L的生物学功能奠定了实验基础。

Prokaryotic expression of the extracellular region of human OX40 and preparation of its antibody

Objective To prepare novel anti-OX40 functional monoclonal antibodies and characterize their distinct biological functions. Methods The gene fragment of extracellular region of OX40 was amplified by PCR and cloned into pET-32a（＋） prokaryotic expressing vector. The expressed products were purified by Ni sepharose and identified by Western blot. The purified recombinant protein was used as antigen to immunize BALB/c mice. Then the immunized spleen cells were isolated from immunized mice and fuse with Sp2/0, a kind of myloma. After screening by ELISA, hybridomas secreting anti-OX40 mAb were acquired and used to generate specific Abs. At last, biological activities of Abs were investigated by ELISA, Western blot. Results The recombinant OX40 extracellular domain protein was successfully expressed in BL21 and purified by Ni sepharose. It was a protein with about 38 kD molecular weight as analyzed by SDS-PAGE and Western blot. The data of FACS demonstrated that the antiserum had high affinity to OX40 expressed on the membrane of OX40-transfected cells. Conclusion The purified protein OX40 has been successfully obtained. The prepared monoclonal antibody shows high specificity and titer in immunized mice. The preparation of recombinant OX40 and its monoclonal antibody has provided reliable tools for the future study on the biologic activity of OX40/OX40L.