[Evaluation of a cytokeratin 19 assay kit "BALL ELSA CYFRA21-1"].

We evaluated "BALL ELSA CYFRA21-1" kit, an immunoradiometric assay kit for cytokeratin 19. Monoclonal antibodies KS19-1 and BM19-21 are used for immunoadsorbent and indicator, respectively. There was no problems in reproducibility, dilution test and recovery test. Minimum detectable concentration was 0.42 ng/ml. The antigen measured by this kit was immunologically cross-reactive with tissue polypeptide antigen (TPA) and CYFRA21-1 concentration was closely correlated with TPA concentration in patient's serum. One of twenty-six healthy subjects showed serum concentration over a cut-off value of 2.0 ng/ml. Serum CYFRA21-1 concentration elevated in 5 of 10 esophageal cancer patients, 5 of 10 gastric cancer patients, 7 of 10 colorectal cancer patients and 6 of 10 pancreatic cancer patients. Positive rate in patients with benign disease including hepatopathy was low. BALL ELSA CYFRA21-1 kit is reliable and CYFRA21-1 could be a useful tumor marker in gastrointestinal cancer.