Direct radio-labeling of 99Tcm-IgG and its biologic distribution study / 中华核医学与分子影像杂志

ABSTRACT

Objective To establish a novel direct radio-labeling method for 99Tcm-IgG and evaluate the biologic distribution of 99Tcm-IgG.Methods IgG protein was modified with 2-mercaptoethanol.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE),UV-vis spectrophotometer,matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) were used to identify the concentration,integrity of the modified protein.Then radiolabeled IgG-SH with 99TcmO4-was analyzed with radio-HPLC.The product was prepared as frozen kits.The distribution and metabolic process of 99Tcm-IgG were observed in New Zealand white rabbits.Results The relative molecular mass of IgG-SH and IgG measured by SDA-PAGE were similar.The relative molecular mass measured by MALDI-TOF was 1.47× 105.The radiolabeling yield was over 95％,the specific activity was 1.7× 105 GBq/mmol.All the radioactive conjugates of 99Tcm-IgG showed excellent stability in vitro.And more than 95％ conjugates retained their original structures for 6 h in 5％ BAS.Gamma imaging in New Zealand white rabbits showed blood retention in first 4 h after injection,and prominent uptake of radiotracers in the liver,kidneys,and urinary bladder at 24 h after injection,which indicated that 99Tcm-IgG was excreted mainly through the renal route.99Tcm-IgG kept its original biological activity after the modification.Conclusions Direct radio-labeling of 99Tcm-IgG was successfully established.The methods may be useful for radio-modification of monoclonal antibody.