A potential new radiopharmaceutical for parathyroid imaging: Radiolabeled parathyroid-specific monoclonal antibody—I. Evaluation of 125I-labeled antibody in a nude mouse model system

Abstract Radioiodinated BB5-G1, a parathyroid-specific monoclonal antibody, and its F(ab′) 2 and Fab fragments were characterized using a nude mouse model system. Blood clearance studies indicated that the most slowly clearing species was the 125 I-BB5-G1 intact antibody, while the most rapidly clearing one was the 125 I-Fab fragment. 125 I-F(ab′) 2 retained its capacity to localize in the human parathyroid tissue implants with the uptake at 24 h being similar to that observed with the intact antibody. Poor localization was observed with the Fab fragment. These results suggest that BB5-G1 or its F(ab′) 2 fragment may be useful for parathyroid imaging.