(1)探索磁共振成像 ( MRI) 造影剂标记单克隆抗体(McAb)的条件；(2)观察肿瘤特异性MRI造影剂Gd-DTPA-McAb 对肿瘤组织的增强效果。方法　给9只10周龄BALB/c裸鼠皮下注射LS-174T大肠癌细胞以制作肿瘤的动物模型，将CL-3单克隆抗体与DTPA 环二酸酐(c.DTPA)相偶联,再加入钆即得到Gd-DTPA-McAb。观察肿瘤组织在Gd-DTPA-McAb增强后的信号强度变化。结果　(1)当pH=8.0,C/P(c.DTPA与抗体的摩尔比)=1，CL-3浓度=10mg/ml时，c.DTPA与抗体的偶联率最高，达68.2%。(2) Gd-DTPA及Gd-DTPA-McAb对肿瘤组织均有明显的强化作用，两者的区别在于：前者的强化是非特异性的, 而后者的强化则具有肿瘤特异性。结论　靶向MRI(Gd-DTPA-McAb)为早期无创、 定位定性诊断结肠癌(包括其他肿瘤)及其转移灶的显示提供了可行的方法 。

　　Experimental study on gadolinium labeled anti-human colonic carcinoma antibody CL-3 for magnetic resonance imaging diagnosis in nude mice with LS-174T cancer　　Wang Jinwu*，Huang Qiliu， Xu Yikai， et al. Department of Radiology, Nanfang Hospital, the First Military Medical University, Guangzhou 510515 (*Department of Radiology,General Hospital of Chengdu Military District of PLA, Chengdu 610083)

　　【Abstract】　Purpose　The aims of this study were:(1)To find out the optimal measures for the conjugation of gadolinium and monoclonal antibody;(2)To observe the contrast enhancement effect of tissue-specificity with MRI contrast medium-McAb(gadolinium-DTPA-McAb). Methods　Nine nude mice were used as animal models by subcutaneous injection of LS-174T cell.DTPA anhydride and CL-3 monoclonal antibody were first conjugated.Then,gadolinium-acetate was added to label DTPA-McAb and gadolinium-DTPA-McAb was thus available. MRI was performed with a Bruker/Spectrospin Tomikon BMT 1100 MRI system.The enhancing effect of Gd-DTPA-McAb was compared with that of Gd-DTPA. Results　(1) The optimal measures of the conjugation of DTPA anhydride and monoclonal antibody were as follows:pH＝8.0,DTPA anhydride/antibody＝1,CL-3＝10mg/ml.The optimal conjugate rate was 68.2%. (2)Both Gd-DTPA-McAb and Gd-DTPA showed significant enhancement effect in nude mice with LS-174T cancer. The enhancement effect of Gd-DTPA-McAb was tumor-specific,while thaf of Gd-DTPA was not(non-specific).Conclusion　Targeting MRI (Gd-DTPA-McAb) is probably a feasible and promising modality in the early detection of colon cancer (as well as other cancers) and their metastatises.

　　【Key words】　Magnetic resonance imaging　　Antibodies, monoclonal　　Neoplasms, experimentalContrast media

　　MRI靶向诊断的原理与放射免疫显像的原理相似，只是标记的是MRI造影剂，Gd-DTPA标记单克隆抗体(Gd-DTPA-McAb)对肿瘤模型的增强效果国外有少量文献报道［1～4］。MRI靶向诊断的优点是：无创伤、无辐射,可对肿瘤进行定位、定性诊断。对体腔深部的淋巴结是否有转移，肿瘤术后有否残余和(或)复发也能作出肯定的回答。笔者以CL-3单克隆抗体为引导剂，以钆(Gd)为造影剂对裸鼠肿瘤(LS-174T大肠癌)模型的MRI诊断进行实验研究。旨在探索Gd标记McAb的条件及影响标记率的因素，观察Gd-DTPA-McAb对肿瘤模型的增强效果。

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