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P220 Diagnostic challenges in inflammatory bowel disease: fully automated immunoassay profiling of fecal biomarkers

A. Kraemer1, M. Richter-Fecken*1, S. Hejc2, S. Jansen-Skoupy2

1ORGENTEC Diagnostika, R&D, Mainz, Germany, 2Kaiser-Franz-Josef-Hospital, Institute of Laboratory Diagnostics, Vienna, Austria

Background

There is no "gold standard" laboratory test to diagnose inflammatory bowel diseases (IBD). Fecal calprotectin (FC) is an established biomarker for detection and follow-up of IBD. [2], [4]

Fecal lactoferrin (FL), an iron-storing protein from neutrophil granulocytes is a sensitive marker for intestinal inflammation. [3]

Secretory IgA (sIgA) reflects the immunological status of the gastrointestinal tract. Increases in sIgA may be associated with impaired mucosal permeability. [1]

Methods

Samples from 40 consecutive patients presenting at the Kaiser-Franz-Josef-Hospital, Vienna, either with symptoms suggestive for or with confirmed diagnosis of IBD were analyzed with 5 different test systems including two established FC ELISAs (ORGENTEC Diagnostika, Germany; Bühlmann, Switzerland), a rapid fully automated FC test, and two assays in development, FL and a novel sIgA test for the automated Alegria® system (ORGENTEC Diagnostika, Germany). FC, FL and sIgA were extracted and measured according to the manufacturer's instructions.

Results

The coefficients of determination (R2) among the FC tests ranged from 0.84 to 0.98. The correlation of FC Alegria® and FC ORGENTEC ELISA with the Bühlmann FC test was 0.84 and 0.86. FC Alegria® and the FC ORGENTEC ELISA showed excellent correlation (R2= 0.89), especially in the normal and the lower range of FC levels up to 200 µg/g (R2=0.98). The number of samples with FC and FL concentrations below or above the respective cut-off are summarized in Table 1.

Number of samples with concentrations of fecal biomarker below or above the cut-off

FC Bühlmann ELISA > 50 µg/gFC Bühlmann ELISA < 50 µg/g
FC ORGENTEC ELISA > 50 µg/g233
FC ORGENTEC ELISA < 50 µg/g O14
FC for Alegria® > 50 µg/g233
FC for Alegria® < 50 µg/g O14
FL for Alegria® > 7.2 µg/g221
FL for Alegria® < 7.2 µg/g116

Only three samples tested positive with the ORGENTEC FC kits and negative with the Bühlmann test. The recently developed automated FL assay significantly correlated with the established FC test (R2= 0.88). Seven samples showed elevated sIgA as well as elevated FC concentrations.

Conclusion

The novel easy going rapid ORGENTEC FC test for the fully automated Alegria® system showed excellent correlation with established FC tests. This was also the case for the novel FL assay. These new automated fecal immunoassays are possibly helpful candidates for diagnostic work-up of patients with IBD. sIgA concentrations varied, suggesting further studies to elucidate the value of sIgA testing among IBD patients.

References:

[1] Brandtzaeg, P., (2010), Update on mucosal immunoglobulin A in gastrointestinal disease, Curr. Op. Gastroenterol. 26, 554-563

[2] Burri E., Beglinger C., (2012), Faecal calprotectin - a useful tool in the management of inflammatory bowel disease, SwissMed Wkly. 142, w13557

[3] Lewis J.D., (2011), The utility of biomarkers in the diagnosis and therapy of inflammatory bowel disease, Gastroenterology 140, 1817-1826

[4] Montalto G. et al., (2013), Role of fecal calprotectin in gastrointestinal disorder, Eur. Rev. Med. Pharmacol. Sci. 17, 1569-1582