A double monoclonal time-resolved immunofluorometric assay of carcinoembryonic antigen in serum

A non-isotopic heterogeneous non-competitive immunoassay for carcinoembryonic antigen is described. CEA present in serum binds simultaneously to two monoclonal antibodies specific for different antigenic determinants of CEA. One antibody is immobilized on a solid-phase (microtiter well) and the other is biotinylated. The amount of biotinylated antibody bound is measured on the dried solid-phase by time-resolved fluorometry after adding streptavidin labeled with the europium chelate 4,7-bis(chlorosulfophenyl)-1,10 phenanthroline-2, 9-dicarboxylic acid (BCPDA) in the presence of excess Eu3+. The assay is simple to perform, its characteristics are similar to those of other isotopic and non-isotopic techniques, and it is suitable for routine clinical use.