An instant kit method for labeling antimyosin Fab' with technetium-99m: evaluation in an experimental myocardial infarct model.

An instant kit method for labeling antibody Fab' fragments was developed. The method utilizes a ligand exchange reaction between the intermediate complex ~-I'c-D-glucarate and the free suffhydryl groups on the antibody Fab' fragment. Radiolabeling of the Fab' using generator eluate achieves quantitative ~"Tc incorporation in less than 30 min at room temperature. The radiolabel is stable in human plasma for at least 24 hr and stable to incubation with 10 mM diethylenetriaminepentaacetic acid (24 hr) and 1 mM diaminodithiol agent (up to 3 hr). Mouse biodistribution of 9~q'c-antimyosin shows faster blood clearance and lower uptake in the lungs, liver, and spleen in comparison to 1111n-antimyosin. Techne