The clinical significance of antimicrobial serologic responses within an Irish Crohn's disease population.

ABSTRACT

INTRODUCTION: A hyper-responsive adaptive immunologic response to a variety of microbial antigens has been described in Crohn's disease (CD) patients and elevated levels of a number of antibodies have been identified in the sera of CD patients. To date, the serological profiles of an Irish CD population have not been characterized. OBJECTIVES: The aim of this study is to determine the serological profile of Irish patients with CD. Second, we aim to assess the correlation, if any, between serological profile and disease phenotype within this cohort. METHODS: A total of 179 consecutive adults with CD attending a specialist inflammatory bowel disease clinic at a university hospital were recruited. Blood samples were taken and sera were analysed for the expression of pANCA and Crohn's related antibodies. RESULTS: pANCA was present in 47/179 (26.3%), anti-OmpC antibodies were present in 49/179 (27.4%), anti-Saccharomyces cervisiae (ASCA) in 64/179 (35.75%), ASCA IgA in 56/179 (31.28%) and ASCA IgG in 37/179 (20.67%), and anti-CBir antibodies in 97/179 (54.18%). The presence of ASCA IgA (P=0.031), ASCA IgG (P=0.007) and anti-CBir antibodies (P=0.003) were all significantly associated with small bowel involvement. Anti-OmpC, ASCA IgA and anti-CBir antibodies' positivity were all associated with complicated disease behaviour, whereas ANCA positivity was associated with inflammatory disease. CONCLUSION: Our study supports previous findings of an association between serological profiles and disease behaviour and a corresponding association with increased need for surgery. In this genetically homogenous Irish CD study group, the levels of specific antibody responses to commensal gut flora are lower than reported previously in other European and American populations.