Increased antibody response to microbial antigens in patients with Crohn's disease and their unaffected first-degree relatives.

Background: Antibodies directed towards bacterial antigens are considered as serological markers of Crohn's disease. Their role in disease pathogenesis is still under investigation. Aim: Assess the serologic response towards microbial antigens in Crohn's disease patients, their unaffected first-degree relatives and healthy controls. Methods: This retrospective study included 60 Crohn's disease patients, 86 unaffected first-degree relatives and 100 healthy controls. Their sera were tested for anti-chitobioside, anti-laminaribioside, anti-mannobioside, anti-Saccharomyces cerevisiae and anti-outer membrane porin C of Escherichia coli. Results: The prevalence of anti-chitobioside and anti-laminaribioside was higher in Crohn's disease patients and their first-degree relatives than in healthy controls (51.67%, 61.63% and 8%, respectively, for anti-chitobioside and 76.17%, 88.37% and 23.00% for anti-laminaribioside; p < 0.0001). The cumulative semiquantitative immune response against all the tested antibodies was higher in unaffected relatives than in healthy controls (p < 0.001). The quantitative analysis revealed that serum levels of anti-chitobio side, anti-laminaribioside and anti-mannobioside were similar in first-degree relatives and Crohn's disease patients and higher than healthy controls (p < 0.001). Conclusions: Both qualitative and quantitative analysis revealed that unaffected first-degree relatives have increased antibody response to microbial antigens. This impaired immunological response towards enteric microorganisms may result from a genetic predisposition. (C) 2013 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.