Biotinylated Monoclonal Antibody Conjugated to Gadolinium as a Contrast Agent for Magnetic Resonance Imaging of Human Rectal Carcinoma

局部病变是直肠癌最常见的复发方式，预后不佳。为了尽早发现局部复发，我们制备了单抗A7-Gd结合物作为磁共振成像的造影剂，用于区分肿瘤和正常组织。我们检测了单抗A7与Gd通过螯合、异硫氰基苯基EDTA偶联的体外免疫反应性及其在裸鼠体内的分布，单抗A7-Gd保持了与完整单抗A7几乎相同的结合活性。放射性标记单抗A7-Gd在肿瘤中的积聚多于正常小鼠的Ig G-Gd。单抗A7-Gd和正常小鼠免疫球蛋白-Gd均随时间线性消失。在正常组织中的蓄积量随时间呈线性下降，但低于在肿瘤中的蓄积量。注射亲和素后，生物素化chA7Fab在血液和肾脏中的蓄积量显着减少。

Local disease is the most frequent recurrence pattern of rectal carcinoma, and its prognosis is not good. To detect local recurrence as early as possible, we produced the monoclonal antibody A7-gadolinium (Mab A7-Gd) conjugate as a contrast agent for magnetic resonance imaging to distinguish between carcinoma and normal tissue.We examined the in vitro immunoreactivity of Mab A7 coupled to Gd by chelate, isothiocyanobenzyl EDTA and its in vivo distribution in nude mice with human colorectal carcinoma.Mab A7-Gd retained binding activities that were nearly identical to intact Mab A7. More radiolabelled Mab A7-Gd accumulated in the tumor than normal mouse IgG-Gd. Both Mab A7-Gd and normal mouse IgG-Gd disappeared from blood linearly over time. Accumulation levels in normal tissues decreased linearly over time but were lower than those in tumors.The accumulation of biotinylated chA7Fab in the blood and the kidneys decreased significantly after the injection of avidin.