碘化甲胎蛋白抗体在大鼠肝癌中选择性定位研究

本文用亲和层析法纯化的抗体,研究碘化甲胎蛋白(AFP)抗体在大鼠移植性肝癌中的定位和放射免疫显像。做全身扫描的荷瘤鼠27只有肿瘤37个,阳性显像36个,弱阳性1个。荷瘤鼠全身放射性核素含量以每日减少约50％的速率下降,第7天还剩3.6％。肿瘤碘化抗体含量持续保持较高水平,第5天肿瘤放射强度分别是血、脑、肌肉、心、肝、脾、肾的2.49、46.60、15.16、6.21、6.17、5.33、3.03倍。组织切片放射自显影显示碘化抗体在肿瘤内呈特异性浓集。本文还就碘化抗体选择性定位和放射性非靶分布的机理进行了免疫病理学探讨。

SELECTIVE LOCALIZATION OF RADIOIODINATED ANTIBODY TO a-FETOPROTEIN IN TRANSPLANTED HEPATOMA IN RATS

The distribution and radioimmunoimaging of radioiodinated antibody to a-fetoprotein (AFP) in rats with transplanted hepatoma were studied. The specific antibody was isolated from anti-rat AFP rabbit antiserum by affinity purification and a dose of 50 or 150uCi of the radioiodinated antibody was inje-cted intravenously into tumor-bearing rat after the tumors were grown over 1 cm in diameter. On total body scanning, 36 out of 37 tumors in 27 rats scanned were demonstrated, with only a small one in liver poorly defined. Total body radioactivity was determiined every day. It was found that the radioactivity was reduced by about 50% a day and to 3.6% on the 7th day postinjection. The level of radioactivity in tumor was relatively high on 1st, 2nd and 5th days and the tumor/tissue radioactivity ratios in blood, spleen, liver, muscle and brain, determined 5 days after the injection, were 2.49, 5.33, 6.17, 15.16 and 46.6 respectively. By using indirect AFP immunoperoxidase staining and autoradiogra-phy of tissue section, it was found that the number of black grains in tumors was larger than in non-cancerous tissues, and there were more grains in areas with positive AFP immunoperoxidase staining in the tumor. The grains were seen around the membrance of tumor cell as well as inside them. The mechanism of localization of the radioactive antibody in tumor and of nontarget distribution of radioactivity were discussed with an immunopathological approach.