^(131)I-RP215 McAb分子探针的制备、鉴定及荷人肺腺癌裸鼠放射免疫显像

Preparation and identification of ^(131)I-RP215 McAb molecular probe and its application for radioimmunoimaging in lung adenocarcinoma-bearing nude mice

目的制备靶向肺腺癌细胞表面碳水化合物相关抗原(carbohydrate antigen 215,CA215)的核素分子探针^(131)I-RP215单克隆抗体(monoclonal antibody,Mc Ab),鉴定其理化性质并探讨其在荷瘤裸鼠模型中的体内分布情况和放射免疫显像特点。方法采用氯胺T法对Mc Ab RP215进行^(131)I标记,Sephadex G25M柱纯化标记抗体,并鉴定其理化特性,观察该抗体标记物在荷A549裸鼠模型中的生物分布及放射免疫显像情况。结果^(131)I-RP215 McAb标记率为(91.03±2.36)%,纯化后的放化纯度为(93.15±1.40)%,比活度(3.37±0.42)MBq/μg;具有较好的稳定性及免疫活性。荷瘤裸鼠体内生物分布及SPECT显像结果显示,^(131)I-RP215 McAb能够在肿瘤组织中选择性浓聚,^(131)I-RP215 McAb作用24 h时,肿瘤/肌肉比达最高,且瘤体显影最清晰。结论成功制备了特性理想的^(131)I-RP215 McAb分子探针,在荷人肺腺癌裸鼠模型中有较好的显像效果。

Objective To prepare a targeted probe for nuclide labeling of 131I-RP215 monoclonal antibody （McAb） against carbohydrate-associated antigen, carbohydrate antigen 215 （CA215） which are expressed on the surface of lung adenocarcinoma cells, identify the physico-chemical properties of the probe, and to explore its distribution in vivo and radioimmunoimaging （RII） characteristics in tumor-bearing nude mice model. Methods McAb RP215 was labeled with 131I by the chloramine T method, and then the products were purified with the Sephadex G25M column. The physico-chemical properties of the obtained McAbs were studied. Nude mice model bearing human lung adenocarcinoma was established by transplantation of A549 cells. Then the mice received the injection of 131I-RP215 McAbs via tail vein, and the bio-distribution and RII characteristics were observed with single-photon emission computerized tomography （SPECT）. Results The obtained 131I-RP215 McAbs showed a labeling rate of （91.03±2.36）%, a radiochemical purity of （93.15±1.40）%, and a specific activity of 3.37±0.42 MBq/μg, and had good stabilities and immunological competence. Biodistribution and SPECT imaging showed 131I-RP215 selectively accumulated in tumor tissue, and the target/non-target （T/NT） ratio reached the highest with the clearest tumor imaging at 24 h after injection of McAbs. Conclusion Molecular probes, 131I-RP215 McAbs, with ideal physicochemical properties are successfully prepared, and show satisfactory SPECT imaging in tumor-bearing nude mice.