[Relevance of serologic studies in inflammatory bowel diseases]

The panel of serologic markers for inflammatory bowel diseases (IBDs) is rapidly expanding. Although anti- Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophil cytoplasmic antibodies (atypical P-ANCA) remain the most widely investigated, an increasing amount of experimental data is available on newly discovered antibodies directed against various microbial antigens. Such antibodies include anti-OmpC (outer membrane porin C), anti- Pseudomonas fluorescens (anti-I2) and antiglycan antibodies (anti-laminaribioside carbohydrate antibody [ALCA]), anti-chitobioside carbohydrate antibody [ACCA]), anti-mannobioside carbohydrate antibody [AMCA]) and anti-CBir1; this latter is the first bacterial antigen to induce colitis in animal models of IBD and also leads to a pathological immune response in IBD patients (anti-flagellin antibody). The role of assessment of various antibodies in the current diagnostic algorithm of IBD is rather questionable due to their limited sensitivity. In contrast, the association of serologic markers with disease behavior and phenotype is getting more into the focus of interest. An increasing number of observations confirm that patients with Crohn's disease expressing multiple serologic markers at high titers are more likely to have complicated small bowel disease (e.g. stricture and/or perforation) and are at higher risk for surgery than those without, or with low titer of antibodies. Creating homogenous disease sub-groups based on serologic response may help develop more standardized therapeutic approaches and may help in a better understanding of the pathomechanism of IBD. Further prospective clinical studies are needed to establish the clinical role of serologic tests in IBD.