Junnikkala S, Hakulinen J, Meri S
Department of Bacteriology, University of Helsinki, Finland.
Eur J Immunol. 1994 Mar;24(3):611-5. doi: 10.1002/eji.1830240318.
Major problems in the immunotherapy of human tumors with complement-activating monoclonal antibodies (mAb) are (i) inherent resistance of tumor cells to complement cytolysis and (ii) a possible undiscriminatory attack against normal cells. In the present study we have developed a procedure to simultaneously direct the complement membrane attack complex and neutralize its inhibitor CD59 (protectin) on human melanoma cells in vitro. G361 melanoma cells were selectively recognized in heterogenous cell mixtures by a complement-fixing mAb (R24) against the tumor cell GD3-ganglioside. Biotinylated anti-CD59 mAb (YTH53.1) was directed to the tumor cells with a high-affinity biotin-avidin bridge using a proportion of R24 as a biotinylated targeting mAb and avidin as a linker. Biotinylated anti-CD59 mAb lost its ability to activate complement, but retained its CD59-neutralizing activity. Thus, it was possible to avoid nonspecific lysis of surrounding erythrocytes and endothelial cells and direct the CD59-neutralizing effect to the tumor cells. As a result the tumor cells were efficiently killed by R24 plus complement while the bystander cells remained viable. These results suggest that it is possible to target an unrestricted complement membrane attack against GD3- and CD59-positive melanoma cells.
用补体激活单克隆抗体（mAb）对人类肿瘤进行免疫治疗存在的主要问题是：（i）肿瘤细胞对补体溶解的固有抗性，以及（ii）可能对正常细胞的无差别攻击。在本研究中，我们开发了一种程序，可在体外同时将补体膜攻击复合物导向人类黑色素瘤细胞，并中和其抑制剂CD59（保护素）。通过针对肿瘤细胞GD3神经节苷脂的补体结合单克隆抗体（R24），在异质细胞混合物中选择性识别G361黑色素瘤细胞。使用一定比例的R24作为生物素化靶向单克隆抗体，抗生物素蛋白作为连接物，通过高亲和力的生物素-抗生物素蛋白桥将生物素化抗CD59单克隆抗体（YTH53.1）导向肿瘤细胞。生物素化抗CD59单克隆抗体失去了激活补体的能力，但保留了其CD59中和活性。因此，有可能避免周围红细胞和内皮细胞的非特异性裂解，并将CD59中和作用导向肿瘤细胞。结果，肿瘤细胞被R24加补体有效杀死，而旁观者细胞仍保持存活。这些结果表明，有可能针对GD3和CD59阳性黑色素瘤细胞进行无限制的补体膜攻击。
