Enzyme immunoassay for the measurement of human tenascin-C on the Bayer Immuno 1™ analyzer

Objectives: To evaluate a new tenascin-C assay performed on the Bayer Immuno 1™ system. Design and methods: The precision was measured using three levels of serum pools. Linearity was tested by diluting patient serum samples containing high tenascin-C concentrations, and the minimal detectable concentration determined by repetitive analysis of the zero calibrator. Preliminary reference intervals were determined by testing serum samples from 220 healthy individuals. Biovariability was estimated in a cohort of 20 apparently healthy subjects over 18 days. The levels of tenascin-C in patients with different liver diseases was tested. Results: The detection limit was 2 ng/mL. At concentrations ranging from 325 to 1957 ng/mL the assay demonstrated within-run and between-run CVs ranging from 4% to 3.6% and 8.4% to 6.7%, respectively. Dilutions of sera were linear and parallel to the standard curve with recoveries ranging from 97% to 100%. The reference interval (central 95% interval) for tenascin-C in serum of healthy adults was 199–906 ng/mL. The variability study yielded an analytical variability, CVA, of 1.8%; a within-subject variability, CVI, of 11.7%; and a between-subject variability, CVG, of 39.3%. tenascin-C concentrations in sera of liver disease patients were significantly increased. Conclusions: The novel assay provides a rapid and reliable procedure for the determination of tenascin-C levels in human sera.