Trond Espen Detlie 1,2, Milada Cvancarova Smastuen 3, Petr Ricanek 1, Stephan Brackmann 1,2, Andreas Rydning 2, Morten Harald Vatn 2 and Jørgen Jahnsen 1,2
Department of Gastroenterology 1Akershus University Hospital. 2University of Oslo, Norway.  3Oslo and Akershus University College.

Serologic nuclear and antimicrobial antibodies are proposed as predictive markers of disease course and complications in inflammatory bowel disease (IBD). Their stability over time is questioned. The aim of this study was to compare antibody titres before and after treatment in newly diagnosed adult IBD patients with regard to gender, age, disease distribution and grade of inflammation.

Material and methods
Patients were included as a prospective population based study (IBSEN II). Diagnoses were revised at follow up. Selected antibodies (ASCA IgA, ASCA IgG, Anti-OmpC IgA, Anti-CBir1 IgG, Anti-I2 and pANCA) (Prometheus laboratories Inc., San Diego) were evaluated at inclusion and follow-up within 2 years. C-reactive protein and faecal calprotectin were used as markers for inflammation.

75% (27/36) was pANCA-positive at diagnosis, 64% (23/36) did not change their status at follow-up, 36% (13/36) did. The percentages of positive values of the other antibodies: Anti-I2 (53%), Anti-OmpC (6%), ASCA IgA (25%), ASCA IgG (3%), Anti-CBir1 (8%). No significantly change at follow-up.

ASCA IgA was positive in 38% (8/21) at diagnosis and 43% (9/21) at follow-up. 24% (5/21) changed their status. Positiv pANCA in 48% (10/21) at diagnosis and 33% (7/21) at follow-up. 33% (7/21) changed their status. Positiv Anti-I2 in 71% (15/21) at diagnosis and 67% (14/21) at follow-up. 14% (3/21) changed their status. Positive values in the remaining antibodies at diagnosis: Anti-OmpC (0%), ASCA IgG (24%, 5/21), and Anti-CBir1 (19%, 4/21). No significant changes at follow-up.

No significant associations between positive serological biomarkers and grade of inflammation, gender, age and disease distribution. (all p>0.60)

Our results suggest that pANCA and ASCA are not stable in IBD patients. This study does not support the use of serological biomarkers as diagnostic nor prognostic tools in an adult routine clinical IBD practice. Our sample size was limited.