Immunoradiometric assay of carcinoembryonic antigen with use of avidin-biotin labeling
Peters, J.; Schmidt-Gayk, H.; Peters, B.; Armbruster, F.P.; Quentmeier, A.; Mathias, D.
Clinical Chemistry 35(4): 573-576
1989
ISSN/ISBN: 0009-9147 PMID: 2649275 Document Number: 334196
In evaluating an enzyme-linked immunoassay of carcinoembryonic antigen (CEA) we found that the IgG fraction of polyclonal anti-CEA antibodies (DAKO) bound very well to the walls of polypropylene test tubes. We therefore developed an immunoradiometric CEA assay based on this binding of polyclonal anti-CEA antibody. We biotinylated a commercially available monoclonal antibody (Hybritech) and bound this to the CEA-anti-CEA bound to the tube wall. For detection we used 125I-labeled streptavidin. In comparison with several immunoassays for CEA this system offered several advantages such as greater linearity of the standard curve (from 0 to 74 micrograms/L), a steeper dose-response curve, and smaller coefficients of variation in the clinically useful range. This assay system may be used for other large molecules, so that only one tracer, the 125I-labeled streptavidin, has to be labeled; thus the technique seems suited for several different assays.