A sensitive, specific, noncompetitive, sandwich-type radioimmunoassayfor carcinoembryonic antigen (CEA) has been developed in our laboratoryl which canbe performed conveniently. The assay involves two monoclonal antibodies, selectedfor high affinity and specificity and also for reaction against antigenic sites on CEAthat are distal from each other. One of these antibodies was labeled with 1251 andthe other was conjugated covalently to biotin. Polystyrene tubes were conjugatedcovalently to avidin. These tubes represent a rapid, simple method for separating theCEA-bound antibody from the free antibody. The biotin-antibody-CEA-"’I-labeledantibody complexes bind to the tubes and CEA concentration is directly related tocounts per minute. This assay can detect the CEA at a concentration of 0.22 ig/L inserum.
展开▼
