$^{99m}Tc-Labeling$ of Monoclonal Antibody to Carcinoembryonic Antigen and Biodistribution

This study was designed to evaluate a direct method of labeling using as a reducing agent, and to investigate whether labeled specific monoclonal antibody against carcinoembryonic antigen (CEA-92) can be used for the scintigraphic localization of human colon cancer xenograft. Purified CEA-92 IgG was fragmented into F and then labeled with by transchelation method using glucarate as a chelator. Labeling efficiency, immunological reactivity and in vitro stability of CEA-92 F were measured and then injected intravenously into nude mice bearing human colon cancer (SNU-C4). Scintigrams were obtained at 24 hour after injection. Then nude mice were sacrificed and the radioactivity was measured Labeling efficiency of injected CEA-92 F , immunoreative fraction and in vitro stability at 24 hour of injected CEA-92 F was 45.2%, 32.8% and 57.4%, respectively. At 24 hour after injection, % ID/g in kidney (46.77) showed high uptake, but %ID/g in tumor (1.65) was significantly higher than spleen (0.69), muscle (0.16), intestine (0.45), stomach (0.75), heart (0.48) and blood (0.45). There was no significant difference between tumor and liver (1.81). Tumor contrast as quantitated by tumor to blood ratio of CEA-92 F was increased significantly (p. The scintigram demonstrated localization of radioactivity over transplanted tumor, but significant background radioactivity was also noted over kidney and abdomen. It is concluded that CEA-92 F can be labeled with by a direct transchelation method using as a reducing agent and labeled CEA-92 F can be used for the scintigraphic localization of human colon cancer xenograft in nude mice model.