NDLI: Proteolysis is a confounding factor in the interpretation of faecal calprotectin.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Dumoulin, Els N. Van Biervliet, Stephanie Langlois, Michel R. Delanghe, Joris R.
Abstract	BACKGROUND: Calprotectin is a 36 kDa calcium and zinc binding protein. An increased level of calprotectin points towards inflammatory bowel disease. However, the biomarker calprotectin shows 14 potential cleavages sites for trypsin. Next to trypsin, also the presence of its inhibitor 1-antitrypsin after a gastrointestinal bleeding may affect calprotectin testing. In this study, effects of trypsin and 1-antitrypsin as potential confounders for faecal calprotectin testing are investigated. METHODS: An in vitro model was created. As calprotectin source, leukocytes were isolated and subsequently lysed (1% Triton X-100) and diluted in faecal matrix. Trypsin digestion was carried out by adding trypsin. Incubation occurred for 24 h or 48 h (37 °C). To study the influence of 1-antitrypsin on trypsin, the same experiment was repeated after adding serum containing 1-antitrypsin. RESULTS: In vitro experiments enabled monitoring of the faecal calprotectin digestion, leading to loss of immunoreactivity. Trypsin activity was a potential confounder in the interpretation of calprotectin, in particular for proximal lesions, where exposure of calprotectin to trypsin is prolonged. Relative calprotectin loss was proportional to the amount of trypsin. Decrease of calprotectin was more pronounced after 48 h of incubation in comparison to 24 h of incubation. Analogue experiments also showed stable calprotectin values after adding 1-antitrypsin. CONCLUSIONS: Transit time, trypsin activity and addition of blood as a source of 1-antitrypsin may be regarded as potential confounders in the interpretation of calprotectin results. Age-related cut-off values depending on the anatomical localisation of the lesions could improve the diagnostic efficiency of calprotectin testing.
File Format	HTM / HTML
ISSN	14346621
Issue Number	1
Volume Number	53
e-ISSN	14374331
Journal	Clinical Chemistry and Laboratory Medicine
Language	English
Publisher	Walter de Gruyter
Publisher Date	2015-01-01
Publisher Place	Germany
Access Restriction	Subscribed
Subject Keyword	Amino Acid Sequence Discipline Clinical chemistry Humans Molecular Sequence Data Metabolism Journal Article Artifacts Chemistry Trypsin Discipline Clinical Chemistry Proteolysis Leukocyte L1 Antigen Complex Analysis Alpha 1-antitrypsin Feces Clinical Chemistry Tests
Content Type	Text
Resource Type	Article
Subject	Biochemistry (medical) Clinical Biochemistry

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