摘要:
Purpose To study the radioactive purity and activity of 131I labeled human single chain variable fragments antibodies (scFv) against anaplastic thyroid carcinoma (ATC),and to explore its distribution and radioimmunoimaging characteristics in tumor bearing nude mice model in vivo so as to provide a new method for anaplastic thyroid carcinoma diagnosis and treatment.Materials and Methods The nude mice model bearing human anaplastic thyroid carcinoma was constructed.The chloramine T method was used to label scFv with 131I and the Sephadex G25M was used for purification of labeled scFv.Labeling rate was determined by trichloroacetic acid method;radiochemical purity,room temperature stability and serum stability were examined using paper chromatography.131I-scFv was injected via tail vein in mice,and the distribution of 131I-scFv in body tissues and organs was analyzed at 12,24,48,72 h after injection.Static SPECT imaging was performed at 12,24,48,72 h after injection to observe the intratumoral accumulation of radioactivity.The SPECT/CT image fusion was performed when the tumor tissues were clearly visible.Results 131I-scFv was purified,and the labeling rate was 91.64%;the radiochemical purity was (93.3 ±0.3)%.The radiochemical purity of 131l-scFv placed at room temperature and the serum for 1,6,12,24 h were all >90%.The radioactive distribution of 131I-scFv in tumor,liver,kidney,intestine and blood was high.SPECT imaging showed 131I-scFv was selectively concentrated in tumor tissue;the targeton-target ratio was the highest at 48 h,and the imaging was most satisfactory.Conclusion 131I-scFv can be successfully prepared.SPECT imaging of 131I-scFv in nude mice model is satisfactory,which lays the foundation for further research in ATC diagnosis and treatment.%目的 测定131I标记的甲状腺未分化癌(ATC)人源单链抗体(scFv)的放射性纯度与比活度,并探讨其在荷瘤裸鼠模型的体内分布情况和放射免疫显像特点,以期为ATC的诊断及治疗提供一种新的方法.材料与方法接种ATC细胞构建荷人ATC裸鼠模型.采用氯胺T法实现scFv的131I标记,Sephadex G25M柱纯化标记抗体,采用三氯醋酸法测定其标记率,采用纸层析法测定131I标记scFv的放化纯度、室温稳定性及血清稳定性.荷瘤裸鼠尾静脉注射131I-scFv后12、24、48、72 h取各组织器官分析131I-scFv在体内组织器官中的生物分布情况,另取荷瘤裸鼠尾静脉注射131I-scFv后12、24、48、72 h进行SPECT静态显像,观察瘤内放射性浓聚,待肿瘤清晰显影,进行SPECT/CT图像融合.结果 纯化后的131I-scFv标记率为91.64%,放化纯度为(93.3±0.3)%;131I-scFv放于室温及血清孵育1、6、12、24 h后所测得放射性化学纯度均高于90%.131I-scFv在肿瘤组织、肝、肾、肠、血液中具有较高的放射性分布.SPECT显示131I-scFv能够在肿瘤组织中选择性浓聚,肿瘤组织靶/非靶比值在48 h时达最高为4.38,且显影最清晰.结论 成功制备131I-scFv,131I-scFv在荷瘤裸鼠模型中有较好的显像效果,为进一步开展ATC的诊断及治疗研究奠定基础.