TC-99M LABELING ON MONOCLONAL-ANTIBODIES VIA N,N'-ETHYLENE-BIS-L-CYSTEINE

A new developed excellent kidney imaging agent, N,N'-ethylene-bis-L-cy steine (EC) has been used as a bifunctional chelating agent (BFCA) for Tc-99m labeling of monoclonal antibodies (MoAb). A new conjugation ag ent yl-1,4-epoxyl-cyclohex-5-ene-2,3-di-carboxyl-imide (HONCE) and a w atersoluble dehydrating agent 1-ethyl-3-(3-dimethylaminopropyl)-carbo- diimide (EDC) were used to accomplish the conjugation of EC with antib odies. A conjugation yield of 30-40% was obtained. The experimental co nditions were optimized for the best conjugation performance. Tc-99m l abeling was then completed after conjugation. More than 80% of the imm unoreactivity was retained after monoclonal antibodies conjugated with EC. More than 70% of the radioactivity was retained in the labeled co mplex Tc-99m-EC-Ab after incubation in fresh EC and cysteine solutions for 16-20 h. The biodistributions of labeled antibody in mice were al so determined.