Autoradiographic Analysis of Radiolabeled Anti-carcinoembryonic Antigen Monoclonal Antibody CEA102 in Colorectal Cancer Using Computed Radiography

Anti-carcinoembryonic antigen monoclonal antibody (MAb) CEA102 was produced by immunization with purified CEA and the specific accumulation of radiolabeled CEA102 in colorectal cancers was investigated by autoradiography of surgical specimens using Fuji Computed Radiography (FCR). Five patients with colorectal cancer were injected intravenously with ¹³¹I-labeled intact CEA102 or its F(ab')₂. Primary tumor and liver metastases were successfully detected by external scanning with a gamma camera in 4 cases. Autoradiographic study of the surgical specimens using FCR showed predominant localization of ¹³¹I-labeled CEA102 in primary tumors and liver metastases in all cases. Even a small liver metastasis (0.5 cm) was clearly visualized in the autoradiogram by FCR. The pixel distribution curves of the density of the respective tissues in the autoradiograms by FCR showed the heterogeneity of the distribution of administered radiolabeled MAb in individual tumors, but the density of the tumors was higher than that of the normal tissues. In the quantitative distribution analysis of CEA102, the uptake of the primary tumor (mean 1.10%ID/kg) was ten-fold greater than that of the normal colon mucosa (mean G.10%ID/kg). These results revealed that the application of MAb has great potential in radioimmunodetection as well as in antibody-directed therapy.     

CEA多表位融合蛋白在胃肠道肿瘤血清学诊断中的研究价值

目的 以CEA多表位融合蛋白为抗原,即ozlf-86/87融合蛋白,检测胃肠道肿瘤患者血清中抗CEA抗体,鉴定融合蛋白的抗原性,为融合蛋白作为诊断抗原提供依据,为下一步动物免疫反应实验奠定基础.方法 以CEA多表位融合蛋白作为诊断抗原,采用间接ELISA法,分别对收集的39例胃癌患者血清、25例结肠癌患者血清、30例慢性胃炎患者血清和30例健康对照者的血清中的抗CEA抗体进行检测,用方差检验分析胃结肠癌患者实验组和慢性胃炎、健康患者对照组血清抗体效价之间差异性.结果 胃癌和结肠癌实验组与对照组血清抗体效价之间差异均有统计学意义（P＜0.01）.对胃癌患者和结肠癌患者血清抗体的诊断敏感度分别为35.9％和44.0％,结论 本实验通过工程菌表达纯化的CEA多表位融合蛋白具有很好的抗原性,对用于血清学诊断的研究有一定的可行性,对制备ELISA血清检测试剂盒提供了理论基础,为下一步免疫反应及抗CEA抗体的制备奠定基础.     

The presence of anti-carcinoembryonic antigen (CEA) antibodies in the sera of patients with gastrointestinal malignancies

Using an enzyme-linked immunoassay we tested the sera of 71 patients with digestive system cancer, 35 patients with various nonmalignant disorders, and 28 normal individuals for anti-CEA activity. Antibodies were found in the sera of 51% of the patients. Most of the patients positive for the antibodies (70%) had no evidence of metastatic disease. Fewer than 10% of the sera from control groups had anti-CEA activity. The authors concluded that the patients suffering from cancer of the GI system are capable of producing tumor-specific antibodies. These antibodies could be used as a tumor marker and/or as a possible index for the function of the immune system. The presence of a large tumor mass could lead to the removal of these antibodies from the circulation.     

癌胚抗原特异性单克隆抗体(Anti-CEA)核酸适配体的筛选

目的:筛选癌胚抗原(carcinoembryonic antigen,CEA)特异性单克隆抗体(Anti-CEA)的核酸适配体(aptamers),为肺癌血清肿瘤标志物核酸适配体的筛选奠定实验基础?方法:利用羧基化琼脂磁珠作为筛选介质,以Anti-CEA为筛选的目标靶分子,通过消减SELEX技术及实时定量PCR技术,从随机ssDNA文库中筛选出与Anti-CEA特异性结合的aptamers,并通过凝胶阻滞实验(EMSA)鉴定筛选到的Anti-CEA-aptamer复合物,然后将得到的第10轮富集文库扩增为双链DNA,通过切胶纯化后,连接PMD18-T载体,转化大肠杆菌DH5α感受态细胞,同时利用交错PCR技术鉴定阳性克隆,经测序,获得aptamers的序列?结果:经过10轮筛选得到了4条与Anti-CEA结合的aptamers,测序结果显示均为不同序列?结论:验证筛选出的与Anti-CEA结合的aptamer,特异性检测结果表明2号aptamer与靶分子结合的特异性很高,且与非特异蛋白无明显吸附,筛选出的aptamers用于识别Anti-CEA,将为肺癌的早期诊断和早期治疗提供新的突破口?     

血卟啉衍生物-癌胚抗原单抗偶联物抗肿瘤特性的研究

目的 研究血卟啉衍生物－癌胚抗原单抗偶联物对表达癌胚抗原（CEA）的肿瘤细胞的特异性杀伤作用。方法 将血卟啉衍生物（HPD）与一种癌胚抗原单克隆抗体－C50单抗，通过碳二亚胺（EDCI）偶联，制备HPD－C50单抗偶联物。以表达CEA的SW1116细胞株和不表达CEA的Hep-2 细胞株用MTT法进行体外肿瘤细胞的杀伤实验。结果 被鉴定偶联物的免疫活性与标准单抗差异无显著性（P＞0．01）。偶联物较游离HPD对表达CEA的肿瘤细胞杀伤效果明显增强（P＜0．05）；显微镜下可见CEA阳性细胞死亡，对非表达CEA细胞，二者的作用无明显差异。对各摩尔比的偶联物进行测定，发现摩尔比为66：1时，杀伤效果最好，其HPD的半数杀伤浓度＜2．2μg/ml。结论 HPD－C50单抗免疫偶联物可特异性地杀伤CEA阳性细胞。     

Comparative biodistributions and rates of catabolism of radiolabelled anti-CEA monoclonal antibody and control immunoglobulin in nude mice with human tumour xenografts showing specific antibody localization

The rate of catabolism of a radiolabelled monoclonal anti-CEA antibody has been compared with that of control IgG₁ in control nude mice and in mice with CEA producing xenografts and antigen negative xenografts. The rate of catabolism of antibody, but not of IgG, was increased 3–4 fold in mice with xenografts localizing the antibody, but not in mice with antigen negative tumours. There was no evidence of immune complex formation and/or clearance of antibody from the serum of xenografted mice and the current interpretation of these findings is that following tumour immune directed fixation, antibody is subsequently catabolized faster than in the general metabolic pool. The present data indicates that this is about six times as rapid as in the animal as a whole on a weight to weight tissue basis.