Abstract: Fab fragment of 3A5, a monoclonal antibody directed against human hepatoma BEL-7402 cells, was prepared by digestion of the McAb and purification through the Sepharose 4B-Mark3 affinity column. By ELISA, McAb 3A5 and the Fab fragment were strongly reactive with hepatoma BEL-7402 cells and weakly reactive with KB cells. Using SPDP as the linker agent, McAb 3A5 and its Fab fragment were conjugated to antitumor antibiotic C1027 separately. As determined by clonogenic assay against hepatoma BEL-7402 cells, the IC50 values for McAb-C1027, Fab-C1027 and C1027 were 4.2x10~(-14)M, 8.6x10~(-16)M and 6.5x10~(-16)M, respectively. Fab-C1027 was 32-fold more potent in cytatoxicity to hepatoma cells than to KB cells, indicatng selective cytotoxicity of Fab-C1027 conjugate to the target cells. Therapeutic effects of the conjugates were evaluated with hepatoma BEL-7402 xenografts in nude mice. After sc transplantation of the tumor, treatment started on day 3, iv, with equivalent dose of C1027, 0.1mg/kg ×6.Fab-C1027 and free C1027 inhibited the tumor growth by 85% and 59% respectively.

Key words: Fab fragment, C1027, Nude mice, human hepatoma

摘要： 抗人肝癌单抗3A5用氯化汞合木瓜蛋白酶消化,经SDS-PAGE、ELISA方法检测证实得到Fab活性片段。单抗3AS及Fab片段与抗癌抗生素C1027偶联,得到3A5-C1027和Fab-C1027偶联物。克隆生成测定对肝癌细胞具有极强的杀伤作用,C1027、3A5-C1027和Fab-C1027的IC50值分别为6.5 x10~(-16)、4.2×10~(-14)M和8.6×10~(-16) M。 Fab-C1027对人咽上皮癌细胞与靶细胞的杀伤活性相比,两者相差32倍,呈选择性杀伤作用。观察C1027、Fab-C1027对移植人肝癌裸鼠的治疗作用,其抑瘤率分别为59％和85％。在可耐受剂量下,C1027对人肝癌有明显的抑制作用,而Fab-C1027显示更强的抑制作用。

关键词: Fab片段, C_(1027), 裸鼠