抗人结肠癌单克隆抗体SC3A在荷瘤裸鼠体内的放射免疫定位研究

本文用~(131)I标记自制的抗人结肠癌单克隆抗体SC3A,进行荷人结肠癌裸鼠体内生物学分布和肿瘤的放射免疫显像研究。结果在注射~(131)I饲—SC3A后24～120h,肿瘤部位的放射性均显示出选择性浓聚,以72～120h的影像最为清晰;而注射~(131)I—鼠IgG则呈全身均匀性分布,无肿瘤部位选择性波聚影像。在72h,13种器官的T/NT均大于2,肿瘤LI为6.94,与扫描显像结果吻合。这些都表明SC3A在生物体内对结肠癌具有良好的选择性和导向作用,抗体可对其供临床体内进一步应用提供了依据。

Selective Radiolocalization of Anti-Human Colon Carcinoma Monoclonal Antibody SC3A in the Nude Mouse Model

Tumor targeting of monoclonal antibody (McAb) SC3A directed against human colon cancer was studied in nude mice bearing human colonic cancer xenograft. The McAb (IgGl) was radiolabeled with 131I by lodogen method. The tumor targeting of 131I-SC3A was compared to that of IgG from normal BALB/c mouse ( mIgG). Results of the labeled antibody uptake after i.v. administration were analysed in terms of the accumulation and localization index (LI) for 13 kinds of normal tissues and the tumor. The tumor uptake of the McAb was determined on days 1, 2, 3, 4 and 5 with an average maximum accretion by day 3. Tumor/normal tissues (T/NT) ratios and LI on day 3 for the McAb were 4.45 and 6.94, respectively. However, whole body scanning and direct measurement of the radioactivity in tumor and normal tissues indicated. SC3A localized in its relevent tumor with perfect selectivity. The images of tumor were clearly discernible especially on days 3, 4 and 5, A faster clearance resulted in a 5 fold increase in T/NT on day 3 in comparison to that of mIgG. The radioactivity measurement of mice dissected 1 and 3 days after 131I-SC3A injection showed that 2.45% and 5.68% of injected dose were recovered per gram of tumor. 131I-mIgG could distribute to various tissue of the whole body without any selectivity. These results suggest that McAb SC3A might provide a useful reagent for diagnosis and treatment of human colon carcinoma.