Comparison of Direct-labeling Method of Antibody with 99mTc and 188Re / 대한핵의학회잡지

ABSTRACT

PURPOSE: We investigated the direct labeling method of antibody with 99mTc and 188Re and examined the stability and function of these labeled compounds in in vitro and in vivo. MATERIALS AND METHODS: Disulfide bond of nonspecific human IgG was reduced to -SH group by 2-mercaptoethanol. Stannous ion was used to reduce 99mTc and 188Re. The stability of 99mTc-IgG and 188Re-IgG was estimated upto 24 hrs. Biodistribution was evaluated in abscess bearing rats at 4 and 24 hr post-injection of 99mTc or 188Re labeled IgG. RESULTS: The number of -SH group per reduced IgG molecule was 2.34. The labeling yield of 99mTc-IgG and 188Re-IgG were 90% and 95%, respectively. The stability of 99mTc-IgG at 1, 4, 6 and 24 hr was 91%, 83%, 78%, 7% and that of 188Re-IgG, high uptake was found on kidney, blood, stomach and abscess (9.42+/-0.68, 1.43+/-0.24, 0.86+/-0.18, 0.72+/-0.10 %ID/g, respectively). The uptakes at 24 hr were kidney, abscess, stomach, and blood in descending order. In case of 188Re-IgG, high uptake at 4 hr post injection appeared on kidney, blood, abscess and stomach (3.92+/-0.62, 1.32+/-0.08, 0.88+/-0.01, 0.26+/-0.06, respectively). The upatkes at 24 hr were kidney, abscess, blood abd stomach in descending order. The abscess to blood uptake ratio of 99mTc-IgG was 0.5 at 4 hr and 2.02 at 24 hr and that of 188Re-IgG was 0.67 and 1.29. CONCLUSION: 99mTc-IgG and 188Re-IgG and 188Re-IgG canbe labeled efficiently with direct labeling method. However, 99mTc-IgG and 188Re-IgG, labeled with direct method, was unstable. Further study in needed to enhance the stability of the antibody labeling.