Korean J Nucl Med.  1999 Feb;33(1):84-93.

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

• Choi TH
• Lim SM
• Choi CW
• Woo KS
• Chung WS
• Lim SJ

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.

Keyword

IgG; biodistribution

MeSH Terms

Abscess
Animals
Humans
Immunoglobulin G
Kidney
Mercaptoethanol
Rats
Stomach
Immunoglobulin G
Mercaptoethanol