Immunoradiometric assay of carcinoembryonic antigen with use of avidin-biotin labeling.
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.
Peters
J
J
Clinical Chemistry Laboratory, University of Heidelberg, F.R.G.
Schmidt-Gayk
H
H
Peters
B
B
Armbruster
F P
FP
Quentmeier
A
A
Mathias
D
D
D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D001710:Biotin; D002272:Carcinoembryonic Antigen / Q000032:analysis*; D005188:False Negative Reactions; D006801:Humans; D007118:Immunoassay; D007124:Immunoenzyme Techniques; D007457:Iodine Radioisotopes; D007700:Kinetics; D011786:Quality Control; D019809:Streptavidin
D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D002272:Carcinoembryonic Antigen; D007457:Iodine Radioisotopes; D001710:Biotin; D019809:Streptavidin