99mTc-labeled HAb18 McAb Fab fragment for radioimmunoimaging in nude mice bearing human hepatocellular carcinoma*

AIM:To establish a method of labeling anti-hepatoma McAb (HAb18) Fab fragment modifier with (99m)Tc.METHODS:HAb18 Fab was modified with 2-iminotholane and labeled with (99m)Tc by transchelation from (99m)Tc GH.Labeling yield, radiochemical purity and immunoreactivity were determined by thin layer chromatography (TLC-SG), paper chromatography (PC), gel chromatography (GC) and cell binding assay, respectively. The nude mice bearing human hepatoma were used for radioimmunoimaging (RII).RESULTS:A radiolabeling yield of 50%-80% was obtained, and immunoreactivity (IR) was 30%-40%. Radioimaging results showed that (99m)Tc-HAb18 McAb Fab fragment was concentrated in the tumor 4-8 hours after injection,and the maximum concentration was seen in 12-24 hours,and the T/NT value was 5.18 and 7.48 at 6h and 8h after the injection.CONCLUSION: (99m)Tc-HAb18 McAb Fab fragment could be specifically localized in the tumor of nude mice bearing human hepatocellular carcinoma within 24 hours and this method might be effectively used for labeling McAb Fab fragment with (99m)Tc.