[Enzyme immunoassay of CEA using monoclonal antibody]

Carcinoembryonic antigen (CEA) is important as one of the tumor markers, and enzyme-immunoassay using monoclonal anti-CEA, which is based on the Sandwich method and unnecessary for the treatment of CEA-extract from serum, was tried in this study. The standard curve obtained from this assay showed lineality on low CEA level. Sensitivity could allow to detect CEA below 5 ng/ml of CEA. Correlation between radioimmunoassay and this EIA was not found in especially high CEA-concentration. Reproducibility respect of Intra-assay and Inter-assay had good results. CEA value yielded by dilution of sample serum coincided with nearly expected value; this result indicated that dilution test was effective. CEA value determined by the assay to be necessary for treatment of extract was higher than that by the assay without treatment. Though the number of test samples used for assay of CEA in serum from various diseases were small, we considered it would be appropriate to set up a normal value range in 0.44-3.16 ng/ml (mean +/- 2 SD) and cut off value at 3.9 ng/ml (mean +/- 3 SD). We have been interested in cancer-specificity on monoclonal antibody, but we could not so for evaluate effects of the assay using monoclonal antibody.