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Clin Chim Acta. 2012 Oct 9;413(19-20):1661-7. doi: 10.1016/j.cca.2012.05.010. Epub 2012 May 18.

Immunoassays distinguishing between HNL/NGAL released in urine from kidney epithelial cells and neutrophils.

Author information

1
Section of Anaesthesia and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden. johan.martensson@karolinska.se

Abstract

BACKGROUND:

The distinction between monomeric human neutrophil lipocalin/neutrophil gelatinase-associated lipocalin (HNL/NGAL), secreted by injured kidney tubular cells, and dimeric HNL/NGAL, released by activated neutrophils, is important to accurately diagnose acute kidney injury (AKI).

METHODS:

132 urine samples from 44 intensive care unit (ICU) patients and five urine samples from non-ICU patients with urinary tract infections (UTIs) were analyzed by two monoclonal enzyme-linked immunosorbent assays (ELISA-1 and ELISA-2). The presence of monomeric and/or dimeric HNL/NGAL in each sample was visualized by Western blotting.

RESULTS:

The ELISA-1 detected both monomeric and dimeric HNL/NGAL whereas the ELISA-2 almost exclusively detected dimeric HNL/NGAL with an area under the receiver-operating characteristics curve (AuROC) of 0.90. The ELISA-1/ELISA-2 ratio detected the monomeric form with an AuROC of 0.92. In 32 AKI patients, dimer-specific ELISA-2 levels decreased pre-AKI whereas the monomer-specific ELISA-1/ELISA-2 ratio gradually increased beyond AKI diagnosis. High ELISA-2 levels and/or low ELISA-1/ELISA-2 ratios detected a predominance of dimeric HNL/NGAL in urine from the patients with UTIs.

CONCLUSIONS:

In combination, our two ELISAs distinguish monomeric HNL/NGAL, produced by the kidney epithelium, from dimeric HNL/NGAL, released by neutrophils during AKI development, as well as reduce the confounding effect of neutrophil involvement when bacteriuria is present.

PMID:
22609864
DOI:
10.1016/j.cca.2012.05.010
[Indexed for MEDLINE]

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