A simple technique of directly labelling antibodies with Re has been developed.The reduction of antibody disulfide groups was achieved by incubation of antibodywith ascorbic acid （pH=6.5）for an hour at room temperature and a solution of excessSnCl2 in sodium gluconate was added to the AA-reduced antibody followed by theaddition of perrhenate

Some factors that influence labelling efficiency

such as thepH of the reaction mixture

the labelling time

and the amount of antibodies andreductive agent

were studied experimentally and a better labelling method wasestablished

The labelling yidlds

as determined by paper chromatography

weregreater that 80%.