Affiliations: *Division of Clinical Pathology, Department of Medical Sciences
Source: Bulletin of Department of Medical Sciences 1996; 38(2) 95-104.
Language: Thai with English abstract
We described a “sandwich” type enzyme immunoassay (EIA) for quantifying carcinoembryonic antigen (CEA) in serum. The CEA was extracted from the serum into acetate buffer (0.16 mol/L, pH 5.0) by heating at 70 ºC for 15 min. The supernatant was incubated in a polystyrene microtiter plate previously coated with anti-CEA. The bound CEA was reacted with anti-CEA conjugated to horseradish peroxidase, and peroxidase activity remaining on the wells of the plate was measured by color development with O-phenylenediamine. The optical density of this colored product was directly related to the concentration of CEA. Intra-and inter-assay CVs accounted for 5% and 10% respectively, with a minimum detectable concentration of 1.2 ng/mL. The calibration curve was linear from 0 to 50 ng/mL. The individual reference interval (3.0-9.1 ng/mL.) was established from 161 subjects. Correlation of 85 samples, which was compared to Roche CEA-EIA, was 0.985 (P<0.05) with a slope of 3.47 and an intercept of 1.09 This in-house CEA-EIA was simple, sensitive and reproducible for using with sera of both normal persons and cancer patients. Moreover, This assay is inexpensive to operate and the cost of reagents was approximately 45 bath per test.