Prevalence of Anti- Antibodies in a Cohort of Patients with Inflammatory Bowel Disease in Norway.

This study assessed the seroprevalence of anti- antibodies in Norwegian patients with inflammatory bowel disease (IBD), specifically ulcerative colitis (UC) and Crohn's disease (CD), compared with healthy controls. Associations between anti- antibody positivity and clinical or laboratory parameters in IBD were also explored. A total of 86 UC patients, 68 CD patients, and 41 healthy controls were prospectively enrolled from four Norwegian hospitals (2013-2022). Diagnosis and disease activity were established using standard clinical, endoscopic, and biomarker criteria. Serum samples were analyzed for total Ig, IgG, IgM, IgA, and IgE antibodies against and using ELISA. Anti- IgG seroprevalence was 4.9% in controls and 3.2% in IBD (3.5% UC, 2.9% CD). IgM seroprevalence was 0% in all groups. IgA seroprevalence was higher in IBD (16.2%) than controls (4.9%), with 14.0% in UC and 19.1% in CD. IgE seroprevalence was low across all groups. Smoking correlated with lower antibody levels and higher surgery rates. In UC, higher anti- IgG and IgE levels were associated with milder disease and better prognosis. Anti-TNFα and azathioprine treatments were linked to higher anti- IgA. Norwegian UC and CD patients had significantly higher anti- total Ig and IgA seroprevalence than healthy controls, indicating increased exposure or immune response. Anti- IgG and IgE may serve as markers of clinical activity in UC. Further research is warranted to clarify the clinical significance of these findings.