Reduction-mediated technetium-99m labeling of antibodies -evaluation of various reducing agents

Three common reducing agents: stannous chloride (SnCl_2), ascorbic acid (AA), 2-mercapoethanol (2-ME) have been compared for their efficacy of labeling antibodies(Abs) with ~(99m)Tc, stability and immunoreactivity of labeled Abs The results showed that 2-ME was an optimum reducing agent, at a molar ratio of 1:2000 for Ab to 2-ME. A ~(99m)Tc labeling efficiency greater than 95% can be obtained, the colloid formation was less than 5%. The radioimmunoimaging of ~(99m)Tc-BAC_5 in nude mice bearing tumor xenografts showed that tumor can be viewed clearly.