Abstract: DIRECT LABELING OF MONOCLONAL ANTIBODY WITH188ReZhang Zhiyong Wang Xiangyun Wu Yonghui Liu Yuanfang(Department of Technical Physics, Peking University,Beijing 100871)Fang Yongxin Yuan Xiangqing(General Hospital of PLA,Beijing 100853)ABSTRACTA convenient and efficient method of direct labeling monoclonal antibodies with 188Re is established. The rapid and complete reduction of 188ReO4 is achieved with SnCl2 in an aqueous mixture solution of citric acid and tartaric acid (molar ratio=1∶3) at pH 5.2. The reduced 188Re solution is then mixed with a NaHSO3－ reduced antibody solution and incubated at room temperature for 2h. The mean labeling efficiency is higher than 95%.The labeled antibody i found stable in vivo and in vitro, and is immunoactive.Keywords Monoclonal antibodies 188Re Radionuclide labeling