Macro-pro-B-type natriuretic peptide (proBNP) and hidden macro-N-terminal proBNP: Case report.

Autor: Nakagawa Y; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan., Nishikimi T; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan; Department of Medicine, Wakakusa Tatsuma Rehabilitation Hospital, Japan. Electronic address: nishikim@kuhp.kyoto-u.ac.jp., Sakai H; Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Japan., Ohno S; Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Japan., Kinoshita H; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan., Inazumi H; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan., Moriuchi K; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan., Kuwahara K; Department of Cardiovascular Medicine, Shinshu University School of Medicine, Japan., Horie M; Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Japan., Kimura T; Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Japan.
Jazyk: angličtina
Zdroj: Clinical biochemistry [Clin Biochem] 2018 Feb; Vol. 52, pp. 148-152. Date of Electronic Publication: 2017 Nov 02.
DOI: 10.1016/j.clinbiochem.2017.10.019
Abstrakt: B-type natriuretic peptide (BNP) is a cardiac hormone widely used as a biomarker for heart failure. Here, we present the first report of extremely high levels of immunoreactive BNP caused by formation of macro-proBNP. A 70-year-old woman with left ventricular hypertrophy and normal systolic function presented with extremely high plasma levels of BNP (35,374pg/ml) and N-terminal proBNP (NT-proBNP; 30,600pg/ml). Our recently developed proBNP immunoassay showed that nearly 100% of her immunoreactive BNP was proBNP. Polyethylene glycol precipitation tests reported extremely low BNP recovery (1.3%), while protein G addition tests also reported a remarkably low BNP fraction (3.3%). Gel filtration chromatography with normal elution buffer combined with BNP immunoassays showed a BNP peak with a retention time slightly shorter than that of IgG. With acidic elution buffer (pH3.0), however this peak disappeared and a new BNP peak consistent with glycosylated human proBNP appeared. These results suggest that in this case most BNP immunoreactivity consisted of macro-proBNP, which is an immune complex composed of proBNP and an anti-proBNP autoantibody. Gel filtration chromatography combined with NT-proBNP immunoassays revealed that the NT-proBNP assay cross-reacts with both the proBNP-IgG complex and proBNP. In addition, with acidic buffer, a new large peak appeared with a retention time the same as that of glycosylated NT-proBNP. These results suggest spuriously high levels of BNP and NT-proBNP are caused by macro-proBNP. Macro-NT-proBNP is not detected by the currently available NT-proBNP assay system.
(Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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