title: Radioimmunometric assay for a monoclonal antibody-defined tumor marker, CA 19-9.
abstract: We describe a solid-phase radioimmunometric sandwich assay for a new tumor marker defined by a monoclonal antibody (19-9). This antibody reacts with a carbohydrate antigenic determinant (CA 19-9) found at low concentrations in sera from healthy individuals but frequently increased in sera from patients with adenocarcinomas. The assay is sensitive and simple to perform. It requires duplicate 100-microL samples and may be performed in 6 h. The concentration of CA 19-9 in samples is determined by reference to a standard curve, which is essentially linear from 0 to 120 arbitrary units/mL. The average CV is approximately 10% in the range of 5.8 to 120 units/mL. The minimum detectable dose is 1.4 units/mL and analytical recovery of CA 19-9 is 97.6 to 100.6%. The average concentration of CA 19-9 in sera from 1020 healthy individuals was 8.4 (SD 7.4) units/mL; only 0.6% of such sera had concentrations greater than 37 units/mL. The assay has high specificity (98.5%), even among patients with benign diseases, and has high sensitivity (up to 79%) for patients with gastrointestinal adenocarcinomas, especially those of the pancreas.
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000032:analysis*; D002648:Child; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000276:immunology*; D011863:Radioimmunoassay; D012737:Sex Factors; D013048:Specimen Handling
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm