~(131)I标记抗人结肠癌单克隆抗体MC_3在荷瘤裸鼠体内分布及肿瘤放射免疫显像

抗人结肠癌单克隆抗体(McAb)MC_3用~(131)Ⅰ标记后在裸鼠人肠癌模型上进行肿瘤定位和放射免疫显像研究。结果显示:体外标记抗体特异性结合率为37.5%,裸鼠体内在48～120h的ECT照相可见在肿瘤部位均有放射性的特异性浓聚,其摄取量随时间延长逐渐增加,肿瘤显影清晰,显像的合适时间为96～120h。而给予非特异性的~(131)Ⅰ-NMIgG后,肿瘤部位未见放射性浓聚,而呈全身均匀性分布。120h肿瘤组织与肝脏及正常肠组织的比值分别为3.61和9.81,肿瘤定位指数为4.26。病理组织学检查显示注射~(131)Ⅰ-MC_3裸鼠肿瘤呈大片坏死,仅局部肿瘤边缘尚存少数完整的肿瘤组织。提示McAbMC_3用于肠癌的诊断和导向治疗可能有良好的前景。

Biodistribution and radioimmunoimaging of ~(131)I-labeled monoclonal antibody MC_3 in nude mice bearing human rectum cancer

Biodistribution and radioimmunoimaging of ~(131)I-labeled specific monoclonalantibody MC_3 against human colon mucoid adenocarcinoma in tumor-bearing nude micewere studied. The specific binding rate of the monoclonal antibody MC_3 to rectum cancercells in vitro was 37.5%. In nude mice bearing human rectum cancer xenografts a clearimage of tumor was obtained by ECT camera between 48--120 h after injection of labe-led MC_3. The concentration of MC_3 in tumor increased with time and the optimal imagingtime was 96--120 h after injection. Where as injection of ~(121)I-NMIgG in-to the nudemice resulted in an equal distribution in the whole body. 120 h after injection of ~(131)I-MC_3 the tumor/liver and tumor/normal colon distribution ratios were 3.61 and 9.81 respec- tively, and the localization index of tumor was 4.26. Histological examination showedthat in the ~(131)I-MC_3 concentrated tumor there were large areas of necrosis and only afew round cancer cells remained near the capsule of the tumor. The results showed that monoclonal antibody MC_3 may be useful in localization andtargeting treatment of human colon-rectal cancers.