Department of Ultrasound, Second Affiliated Hospital of Soochow University, Suzhou 215004, Jiangsu, China.
Chin Med J (Engl). 2013 Apr;126(7):1333-6.
We previously reported that iodine-131((131)I)-labeled anti-pro-gastrin-releasing peptide (ProGRP(31-98)) monoclonal antibody D-D3 could selectively accumulate in the tumor sites of nude mice bearing small cell lung cancer (SCLC) xenografts. However, (131)I-D-D3 was cleared slowly from the body, and the best radioimmunoimaging time for SCLC was 72 - 96 hours after injection. The aims of this study were to radiolabel anti-ProGRP(31-98) D-D3 monoclonal antibody with technetium-99m ((99m)Tc) and to investigate the biodistribution of this antibody in healthy ICR mice.
D-D3 was labeled with (99m)Tc via the 2-mercaptoethanol reduction method. (99m)Tc-D-D3 was purified by the gel column separation method. The labeling efficiency and radiochemical purity were measured by thin-layer chromatography. The immunological activity of (99m)Tc-D-D3 was determined with cell conjugation assays. (99m)Tc-D-D3 was injected into healthy ICR mice via a tail vein, and all the healthy ICR mice were sacrificed by cervical dislocation at a designated time. Then, the blood and major organs were removed and weighed, and counted in a gamma scintillation counter to determine the percentage of the injected dose per gram (%ID/g).
The labeling rate and the radiochemical purity of (99m)Tc-D-D3 were (73.87 ± 2.89)% and (94.13 ± 4.49)%, respectively. The immunobinding rates of (99m)Tc-D-D3 to the human small cell lung cancer NCI-H446 cell line and lung adenocarcinoma A549 cell line were (81.2 ± 2.37)% and (24.3 ± 1.46)%, respectively. The distribution data of normal ICR mice demonstrated that (99m)Tc-D-D3 was mainly distributed in the liver, kidney and lung, and less in the brain tissue and muscle.
(99m)Tc-D-D3 antibody not only had high radiochemical purity, but also had good stability both in vitro and in vivo, and maintained good immunological activity. (99m)Tc-D-D3 was metabolized mainly in the kidney and liver, and the blood radioactivity decreased rapidly. Thus, (99m)Tc-D-D3 is conducive to the radioimmunoimaging of SCLC.
我们之前报道过，碘-131((131)I)-标记的抗胃泌素释放肽（ProGRP(31-98)）单克隆抗体 D-D3 可以选择性地在携带小细胞肺癌（SCLC）异种移植物的裸鼠肿瘤部位聚集。然而，(131)I-D-D3 从体内清除缓慢，SCLC 的最佳放射免疫成像时间是注射后 72-96 小时。本研究的目的是用锝-99m ((99m)Tc) 标记抗 ProGRP(31-98) D-D3 单克隆抗体，并研究该抗体在健康 ICR 小鼠中的生物分布。
D-D3 通过 2-巯基乙醇还原法标记 (99m)Tc。(99m)Tc-D-D3 采用凝胶柱分离法纯化。采用薄层层析法测定标记效率和放射化学纯度。细胞偶联试验测定 (99m)Tc-D-D3 的免疫活性。(99m)Tc-D-D3 通过尾静脉注入健康 ICR 小鼠，所有健康 ICR 小鼠均在指定时间通过颈椎脱位处死。然后取出血液和主要器官称重，并在伽马闪烁计数器中计数，以确定每克注射剂量的百分比（%ID/g）。
(99m)Tc-D-D3 的标记率和放射化学纯度分别为（73.87±2.89）%和（94.13±4.49）%。(99m)Tc-D-D3 与人小细胞肺癌 NCI-H446 细胞系和肺腺癌 A549 细胞系的免疫结合率分别为（81.2±2.37）%和（24.3±1.46）%。正常 ICR 小鼠的分布数据表明，(99m)Tc-D-D3 主要分布在肝脏、肾脏和肺部，而在脑组织和肌肉中分布较少。
(99m)Tc-D-D3 抗体不仅放射化学纯度高，而且在体内外均具有良好的稳定性，且保持良好的免疫活性。(99m)Tc-D-D3 主要在肾脏和肝脏中代谢，血液放射性迅速下降。因此，(99m)Tc-D-D3 有利于 SCLC 的放射免疫成像。
