Radioimmunodetection of cancers containing carcinoembryonic antigen and alpha-fetoprotein
Wang, X.H.; Wang, L.S.; Shi, L.; Yang, J.; Ma, X.Q.; Luo, H.N.; Zhou, Z.F.; Xu, G.C.; Li, G.X.
Chinese Medical Journal 101(3): 175-180
1988
ISSN/ISBN: 0366-6999 PMID: 2457471 Document Number: 325518
We used radiolabeled antibodies to carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) to detect and localize CEA- or AFP-producing tumors. The monoclonal antibody to CEA and affinity purified antibody to AFP were prepared and labeled with 131I by iodogen method. The radioantibodies had 95% of radiochemical purity, 2.16-12 mCi per mg of specific radioactivity, and 80%-93% of specific immunoreactivity. Images were made with a r-scintillation camera, at about 48 hours after intravenous injection of a dose ranging from 0.82 to 3.5 mCi of the labeled antibodies (140-590 .mu.g of protein), and a dual radionuclide subtraction technique with computer-assisted processing was used to enhance the tumor-related activity. In 10 patients with CEA-producing tumors, 7 of 8 primary lesions were positive for the CEA radioimmunodetection, and of 15 secondary lesions, 11 were positive and 4 weakly positive. In 10 patients with AFP-producing tumors (liver cancer), 9 of 10 intrahepatic lesions were detected by AFP radioimmunodetection. It is interesting that the tumors were detected by this method even in 5 of 6 patients with normal level of plasm CEA or AFP, and one tumor site missed by CT scan was detected too. The main factors for successful application of this method are described. The mechanism of localization of the radioantibodies in tumor is also discussed through an immunopathological approach.