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Novel sensitive cardiac troponin I immunoassay free from troponin I-specific autoantibody interference
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center.
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2014 (English)In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 52, no 7, 1041-1048 p.Article in journal (Refereed) Published
Abstract [en]

Background: Cardiac troponins (cTnI and cTnT) are the recommended biomarkers of myocardial infarction. As cTn-specific autoantibodies (cTnAAb) can interfere with the cTn detection by state-of-the-art cTnI assays, our objective was to develop a sensitive cTnI immunoassay free from this analytical interference. Methods: The assay used antibody-coated spots containing three capture Mabs/Fabs directed against the N-terminus, midfragment and C-terminus of cTnI and a europium chelate-labeled tracer Mab against the C-terminus. Following a 3-h sample incubation and washing, cTnI was quantified by time-resolved fluorometry. Results: The limit of detection (LoD) was 2.9 ng/L and the assay was linear up to 50,000 ng/L. The total precision of 10% CV was not reached, but 20% CV was reached at 10 ng/L. Mean cTnI (10-50,000 ng/L) recoveries were 100% and 119% in three cTnAAb-positive and two cTnAAb-negative individuals, respectively, verifying the interference resistance of the antibody design used. On average, Architect hs-cTnI assay gave seven-fold higher cTnI concentrations than the new assay but the correlation between the assays was good (r=0.958). Of apparently healthy individuals (n=159), 18% had measurable cTnI values (>LoD) and 10% were cTnAAb-positive. The proportion of measurable cTnI values, however, was significantly higher in cTnAAb-positive individuals (13/16, median cTnI 8.5 ng/L) than in cTnAAb-negative individuals (15/143, median cTnI <LoD) (p<0.001). Conclusions: Although the developed sensitive cTnI assay without cTnAAb interference takes too long for diagnostic purposes, it could serve as an important analytical tool for exploring the impact of cTnAAbs for cTn testing and for unraveling the etiology behind cTn-related autoimmune responses.

Place, publisher, year, edition, pages
2014. Vol. 52, no 7, 1041-1048 p.
Keyword [en]
antibody-coated spot, autoantibody, cardiac troponin I, immunoassay, interference, myocardial infarction
National Category
Biomedical Laboratory Science/Technology
URN: urn:nbn:se:uu:diva-230108DOI: 10.1515/cclm-2013-1044ISI: 000338852700023OAI: oai:DiVA.org:uu-230108DiVA: diva2:742438
Available from: 2014-09-01 Created: 2014-08-19 Last updated: 2014-09-01Bibliographically approved

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Lindahl, BertilVenge, Per
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CardiologyUCR-Uppsala Clinical Research CenterBiochemial structure and function
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