TC-99M DIRECT LABELING OF ANTI-CEA MONOCLONAL-ANTIBODIES - QUALITY-CONTROL AND PRECLINICAL STUDIES

The anti-carcinoembryonic B2C114 monoclonal antibody was radiolabeled with Tc-99m by a direct method and quality control tested in vitro by instant thin layer chromatography, gel column scanning and cellulose a cetate electrophoresis and assessed in vivo for radioimmunodetection o n a murine spontaneous mammary carcinoma. The optimal results of perce nt Tc-99m bound to protein were obtained at a dithiothreitol:antibody molar ratio ranging from 800:1 to 1000:1 and at a methylene diphosphon ate:stannous fluoride weight ratio of 4.3:1. Although cysteine removed up to 18% of the label during the first 4 h, the stability of the tra cer appeared to be excellent in human serum at 37 degrees C and when c hallenged with DTPA. Tc-99m-labeled B2C114 demonstrated good and speci fic in vivo tumor targeting.