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[目的]采用99mTc标记抗人CEA小分子嵌合抗体Rch24 F(ab’)2,研究其在荷人结肠癌裸鼠体内的生物学分布及放射免疫显像的特征与应用价值。[方法]采用SnCl2直接还原法标记抗体,快速薄层层析法(ITLC)测定抗体的标记效率、放化纯度和体外稳定性,ELISA检测标记抗体的免疫比活性。荷人结肠癌裸鼠尾静脉注射99mTc-Rch24 F(ab’)2后,研究标记抗体在裸鼠体内的生物学分布,并进行肿瘤显像。[结果]99mTc-Rch24 F(ab’)2的标记率为90%,放化纯度>95%。99mTc-Rch24 F(ab’)2的放射比活为840MBq/mg,免疫比活性为65.7%。标记抗体24h时放射性脱落小于5%。荷瘤裸鼠注射99mTc-Rch24 F(ab’)23h后即可观察到肿瘤影像,5~24h均可获得清晰的肿瘤影像,标记抗体在体内呈肿瘤靶向性分布,12h时肿瘤的摄取和多数脏器T/NT比值均达到最高水平。[结论]99mTc-Rch24 F(ab’)2在体内靶向分布于结肠癌肿瘤组织,具有较高的T/NT比值并可在肿瘤局部滞留,注射99mTc-Rch24 F(ab’)25h后肿瘤成像满意。99mTc-Rch24 F(ab’)2在临床肿瘤的放射免疫分子显像诊断中具有良好的应用前景。
[Objective] To investigate the biological distribution of Rch24 F (ab ’) 2, a small molecule anti-human CEA chimeric antibody, in 99mTc human colon cancer nude mice and its diagnostic value and application value. [Method] The labeling efficiency, radiochemical purity and in vitro stability of the antibody were determined by SnCl2 direct reduction method and fast thin layer chromatography (ITLC). The specific immunological activity of the labeled antibody was detected by ELISA. After injection of 99mTc-Rch24 F (ab ’) 2 into the caudal vein of human colorectal cancer nude mice, the biological distribution of the labeled antibody in nude mice was studied and tumor imaging was performed. [Result] The labeling rate of 99mTc-Rch24 F (ab ’) 2 was 90% and the radiochemical purity was> 95%. The specific activity of 99mTc-Rch24 F (ab ’) 2 was 840 MBq / mg, and the specific immunocompetence was 65.7%. The labeled antibody is less than 5% radioactively shed at 24h. Tumor imaging was observed 23 h after injecting 99mTc-Rch24 F (ab ’) into nude mice bearing tumors, and clear tumor images were obtained after 5 to 24 hrs. The labeled antibody showed tumor-targeted distribution in vivo. At 12 h, tumor uptake and Most organs T / NT ratio reached the highest level. [Conclusion] 99mTc-Rch24 F (ab ’) 2 is targeted to colon cancer tissues in vivo and has a high T / NT ratio and can be locally retained in the tumor. After 99mTc-Rch24 F (ab’ Satisfactory imaging. 99mTc-Rch24 F (ab ’) 2 has good application prospect in the diagnosis of clinical tumor with radioimmunoimaging.