Experimental study of radioimmunodetection using anti-AFP monoclonal antibody

Radioimmunodetection is to be expecting as a method to detect the localization of cancer using the monoclonal antibody. In this paper, we discussed the possibility of radioimmunodetection of human hepatocellular carcinoma using anti-AFP monoclonal antibody together with tumor-bearing mice. Anti-AFP monoclonal antibody (19F12) was prepared by the method of B cell hybridoma. It was labeled with 125I or 131I using chloramine T method. Male athymic mice (BALB/c-nu/nu, 6 weeks) were inoculated with hepatoma (NuE) or gastric cancer (MKN45). Hepatoma bearing nude mice were intravenously injected of labeled 19F12 1.85 ∼ 3.70 MBq (50 ∼ 100 μCi) [48.1 ∼ 66.6 MBq (13 ∼ 18 mCi)/mg protei], and were imaged daily intervals. Eight days post injection, the mice were killed and biodistribution was determined. Tumor localization was clearly visible 24 hrs after administration of radiolabeled antibody, and became increasingly clear as body background decreased. Tumor to liver ratio of hepatoma was prominently higher than that of gastric cancer. Comparing to 67Ga-citrate which resulted in poor tumor to liver ratio, the radioiodinated monoclonal antibody gave much higher ratio. Therefore, this anti-AFP monoclonal antibody is thought to be very promising agent to detect the localization of hepatoma in the liver, and to visualize the metastatic lesions. (author)