一种新型的重组单链三特异抗体的构建与表达

双特异抗体由于其缺乏共刺激信号 ,激活的T细胞往往会导致凋亡。为了更有效地杀伤肿瘤细胞 ,构建了抗卵巢癌单链×抗CD3单链×抗CD2 8单域重组三特异抗体的表达载体。利用大肠杆菌中的分子伴侣FkpA与三特异抗体共表达 ,提高了三特异抗体的在BL2 1Star菌中的可溶性原核表达。ELISA结果显示 ,可溶性的重组单链三特异抗体 (sTRI)与SK OV 3细胞的膜抗原 ,Jurkat细胞上的CD3分子以及重组CD2 8抗原均有较强的结合活性。桥连试验证明该抗体能同时与SK OV 3细胞和Jurkat细胞结合。体外杀伤试验表明该抗体能激活外周血T细胞来杀伤肿瘤细胞。形态学观察也进一步说明该抗体具有良好的结合活性以及体外杀伤活性。这种新型的重组单链三特异抗体为基于T细胞的癌症免疫治疗建立了一个新的技术平台。

A New Model of Trispecific Antibody Resulting the Cytotoxicity Directed against Tumor Cells

Bispecific antibodies (BsAb) with specificity to both tumor cells and CD3 molecule were believed to be promising immunological tools for the therapy with minimal residual diseases by activating cytotoxic T cells. However, without costimulatory molecule CD28, the activated T cells tended to apoptosis. In order to kill tumor cells more efficiently, a recombinant multifunctional single-chain trispecific antibody (scTsAb), which contains anti-ovarian carcinoma (OC) scFv, anti-CD3 scFv and V H domain of anti-CD28 antibody, was constructed and expressed in E. coli BL21 Star strain. The scTsAb showed strong binding avidities to membrane antigen of SK-OV-3 cell, CD3 molecule on Jurkat cell, and recombinant CD28 antigen. It was further demonstrated that this scTsAb could activate peripheral blood T cells to elicit strong cytotoxicity against SK-OV-3 cells. This new type of recombinant scFv antibody set up a new technological platform for T cells based immunotherapy against cancer, especially with the failure on MHC antigen presentation or absence of costimulating signal.