Labeling conditions of antibody IgG2a (Mouse) with90Y and99mTc and in-vitro stability studies

Abstract

Mouse serum was fractionated and isolated to pure mose sub-class immunoglobulin (IgG1, IgG2a, IgG2b) on protein A-sepharose 4B Microprecipition method was used to ascertain the purity of mouse IgG-sub class, labeling and coupling efficiecy with90Y and99mTc were determined by paper chromatography as a simple and rapid tool for analysis. The parameters investigated included the ratios of DTPA: IgG2a and DTPA: Sn, pH and protein concentrations. The optimal coupling efficiency for90Y was achieved at DTPA to IgG2a molar ratio of 1∶1 pH 8,4 and specific activity of 2 μCi/μg for IgG2a coupled with about 1 goup of DTPa per 1 molecule of IgG2a, while the optimal coupling efficiency for99mTc was achieved at a DTPA to IgG2a molar rato of 50:1, pH4 and specific activity of 1 μCi/μg for IgG2a. Affinity column chromatography with sephadex G50 and protein A sepharose 4B were used to determine the immunoreactive and non-immuoreactive mouse antibody IgG2a coupled with DTPA at different molar ratios and99mTc90Y atoms incorporated into each antibody. Anti-IgG2a affinity column and anti-human transferrin affinity column were used to determine in vitro stability of99mTc DPTa-IgG2a. Freeze-dried kit of IgG2a-Sn-DTPA to be labeled with99mTc was prepared under sterile condition Each vial contained 1.0 mg IgG2a-Sn-DTPA in about 100 μl.