A study of labeling of monoclonal antibody C50 with ~(99)Tc~m and using for radioimmunoimaging

Objective To provide an accurate and scientific method of radionuclide imaging with 99 Tc m-C50. Methods The labeled C50 was derived by iminothiolane and ligand exchange from 99 Tc mO(GH) -_2. HPLC was used to analyse the modified antibody and labeled antibody, labeling efficiency was measured by paper chromatography. Radioimmunoimaging was performed on human colon tumor bearing nude mice. Results The labeling efficiency of the labeled antibody was 97%, with 4% colloidal 99 Tc m in it; the in vitro competition test showed that 99 Tc m being bound up with the antibody at high affinity. The stability of the iminothiolane modified antibody could be kept at 4 ℃ for 3 months. The biodistribution study showed that the tumor radioactivity uptake at 24 h postinjection was the highest, the ratio of tumor to muscle was 4.03. Conclusion The labeling method applied to the preparation of 99 Tc m labeled antibody C50 was successful, and appears to be equally applicable for labeling other antibodies.