DIRECT TC-99M LABELING OF MONOCLONAL-ANTIBODIES - EVALUATION OF REDUCING AGENTS AND HPLC ANALYSIS

Human IgG was used as a model antibody and the results for direct Tc-9 9m labeling of IgG using 2-mercaptoethanol(2-ME), dithiothreitol(DTT) and ascorbic acid (AA) as reducing agents were evaluated. DTT was chos en as reducing agent and an intact monoclonal antibody (3)H11 waslabel ed with Tc-99m with a labeling yield of more than 98% while its Fab fr agment was labeled with Tc-99m in less than 35% yield. The Tc-99m labe led antibodies were analysed by HPLC on a size exclusion column with a n eluent of 0.1 mol/L PBS(pH 7.0), and the in vitro stability of Tc-99 m-3H11 was investigated. HPLC analysis revealed that Tc-99m-3H11 Fab i s not in a singular structure, and the procedure for direct Tc-99m lab eling of antibody's Fab Fragment should be further investigated.