Proteolysis is a confounding factor in the interpretation of faecal calprotectin
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Els N. Dumoulin
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 α1-antitrypsin after a gastrointestinal bleeding may affect calprotectin testing. In this study, effects of trypsin and α1-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 α1-antitrypsin on trypsin, the same experiment was repeated after adding serum containing α1-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 α1-antitrypsin.
Conclusions: Transit time, trypsin activity and addition of blood as a source of α1-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.
Acknowledgments
The authors would like to thank Thermo Scientific (Uppsala, Sweden) for providing the necessary calprotectin reagents. We also wish to thank Elke Lecocq, Jonas Himpe and Mieke Hutsebaut for their technical support.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Financial support: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Role of sponsor: The funding organisation(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
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©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Editorial
- Harmonisation of specialist training and continuing professional development in laboratory medicine: a long but necessary journey
- Reviews
- Laboratory medicine in the European Union
- Role of leptin in female reproduction
- Mini Review
- Interrelatedness between C-reactive protein and oxidized low-density lipoprotein
- General Clinical Chemistry and Laboratory Medicine
- Comparison of approaches and measurement of continuing professional development for specialists in laboratory medicine within four European countries
- Point-of-care urine albumin in general practice offices: effect of participation in an external quality assurance scheme
- Triple positive antiphospholipid antibody profile in outpatients with tests for lupus anticoagulants
- Effects of cigarette smoking on circulating leukocytes and plasma cytokines in monozygotic twins
- Proteolysis is a confounding factor in the interpretation of faecal calprotectin
- Urinary neutrophil gelatinase-associated lipocalin and clinical outcomes in chronic kidney disease patients
- Cancer Diagnostics
- Quantification of adult T-cell leukemia/lymphoma cells using simple four-color flow cytometry
- Serum fucosylated haptoglobin in chronic liver diseases as a potential biomarker of hepatocellular carcinoma development
- Cardiovascular Diseases
- Increased serum homocitrulline concentrations are associated with the severity of coronary artery disease
- S100B concentrations increase perioperatively in jugular vein blood despite limited metabolic and inflammatory response to clinically uneventful carotid endarterectomy
- Long-term biological variability of galectin-3 after heart transplantation
- Diabetes
- Evaluation of a next generation direct whole blood enzymatic assay for hemoglobin A1c on the ARCHITECT c8000 chemistry system
- The 13C-glucose breath test is a valid non-invasive screening tool to identify metabolic syndrome in adolescents
- Comparison of a direct enzymatic assay and polyacrylamide tube gel electrophoresis for measurement of small, dense low-density lipoprotein cholesterol
- Letters to the Editor
- Comparison of Abbott Architect high-sensitivity troponin I in Rapid Serum Tubes and plasma
- Can EDTA, EDTA-fluoride, and buffered citrate tubes be used for measurement of HbA1c on the Bio-Rad D10?
- How to reduce EDTA contamination in laboratory specimens: a Tunisian experience
- Does mean platelet volume share any relationship with biochemical and hematological parameters?
- Association of retrospective markers of glycemia and the use of continuous glucose monitoring in white adults with type 2 diabetes mellitus – a preliminary report
- Operative performances and efficiency for infectious disease testing of two immunochemistry analyzers – Abbott ARCHITECT i2000SR and DiaSorin Liaison XL
Articles in the same Issue
- Frontmatter
- Editorial
- Harmonisation of specialist training and continuing professional development in laboratory medicine: a long but necessary journey
- Reviews
- Laboratory medicine in the European Union
- Role of leptin in female reproduction
- Mini Review
- Interrelatedness between C-reactive protein and oxidized low-density lipoprotein
- General Clinical Chemistry and Laboratory Medicine
- Comparison of approaches and measurement of continuing professional development for specialists in laboratory medicine within four European countries
- Point-of-care urine albumin in general practice offices: effect of participation in an external quality assurance scheme
- Triple positive antiphospholipid antibody profile in outpatients with tests for lupus anticoagulants
- Effects of cigarette smoking on circulating leukocytes and plasma cytokines in monozygotic twins
- Proteolysis is a confounding factor in the interpretation of faecal calprotectin
- Urinary neutrophil gelatinase-associated lipocalin and clinical outcomes in chronic kidney disease patients
- Cancer Diagnostics
- Quantification of adult T-cell leukemia/lymphoma cells using simple four-color flow cytometry
- Serum fucosylated haptoglobin in chronic liver diseases as a potential biomarker of hepatocellular carcinoma development
- Cardiovascular Diseases
- Increased serum homocitrulline concentrations are associated with the severity of coronary artery disease
- S100B concentrations increase perioperatively in jugular vein blood despite limited metabolic and inflammatory response to clinically uneventful carotid endarterectomy
- Long-term biological variability of galectin-3 after heart transplantation
- Diabetes
- Evaluation of a next generation direct whole blood enzymatic assay for hemoglobin A1c on the ARCHITECT c8000 chemistry system
- The 13C-glucose breath test is a valid non-invasive screening tool to identify metabolic syndrome in adolescents
- Comparison of a direct enzymatic assay and polyacrylamide tube gel electrophoresis for measurement of small, dense low-density lipoprotein cholesterol
- Letters to the Editor
- Comparison of Abbott Architect high-sensitivity troponin I in Rapid Serum Tubes and plasma
- Can EDTA, EDTA-fluoride, and buffered citrate tubes be used for measurement of HbA1c on the Bio-Rad D10?
- How to reduce EDTA contamination in laboratory specimens: a Tunisian experience
- Does mean platelet volume share any relationship with biochemical and hematological parameters?
- Association of retrospective markers of glycemia and the use of continuous glucose monitoring in white adults with type 2 diabetes mellitus – a preliminary report
- Operative performances and efficiency for infectious disease testing of two immunochemistry analyzers – Abbott ARCHITECT i2000SR and DiaSorin Liaison XL
