Measurement of Serum IgG Anti-Integrin αvß6 Autoantibodies Is a Promising Tool in the Diagnosis of Ulcerative Colitis.

IgG anti-integrin αvß6 autoantibodies (IgG anti-αvß6) have been described as highly sensitive and specific markers of ulcerative colitis (UC) in the sera of Japanese inflammatory bowel disease (IBD) patients. We aimed to evaluate the diagnostic performance of IgG anti-αvß6 as a biomarker in Swedish patients with IBD or irritable bowel syndrome (IBS). The study included adult UC (n = 59), Crohn's disease (CD, n = 38), and IBS patients (n = 100). Partial Mayo score and Harvey−Bradshaw index were used to assess disease severity for UC and CD, respectively. Serum levels of IgG anti-αvß6, reported as absorbance units (AU), were measured using an in-house ELISA where the 95th percentile of 76 healthy controls defined positivity. Faecal calprotectin (fCP) was measured using a commercial assay. The majority of the IBD patients were on medical treatment, and many were in remission (UC: 40.7%; CD: 47.4%). Seventy-one percent of the UC patients, 74.2% of CD patients, and 23.1% of the IBS patients had fCP test results >50 mg/kg. The UC group had significantly higher IgG anti-αvß6 levels (median: 1.76 AU) than the CD and IBS groups (0.34 and 0.31 AU, both p < 0.0001). The diagnostic sensitivity of IgG anti-αvß6 in UC was 76.3%, and the specificities were 79.0% (vs. CD) and 96.0% (vs. IBS). The IgG anti-αvß6 levels related to disease severity of the UC patients (p < 0.01−0.05). Our study shows that IgG anti-αvß6 is associated with UC in Swedish IBD patients and that the levels of the autoantibodies reflect disease severity. IgG anti-αvß6 could be an attractive complement to fCP in the diagnostic work up of IBD patients.