SELECTIVE LOCALIZATION OF RADIOIODINATED ANTIBODY TO a-FETOPROTEIN IN TRANSPLANTED HEPATOMA IN RATS / 解放军医学杂志

ABSTRACT

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.