EFFICIENT ONE-STEP DIRECT LABELING OF RECOMBINANT ANTIBODIES WITH TC-99M

High-affinity bacterially expressed antibody fragments can nowadays be cloned from established hybridomas or, more conveniently, isolated di rectly from antibody libraries displayed on filamentous phage. Such an tibodies can be tagged with C-terminal peptide tags containing one cys teine residue, which represents a convenient functionalisation site fo r a number of applications, including technetium-99m labelling. Here w e describe a simple one-step method for Tc-99m labelling of cysteine-t agged recombinant antibodies with more than 50% radionuclide incorpora tion. The labelled antibodies displayed full retention of immuoreactiv ity and good stability.