FcγRI plays a critical role in patients with ulcerative colitis relapse.

Ulcerative colitis (UC) is a disease that frequently relapses and affects more than 0.1% general population; the underlying mechanism is poorly understood. Published data show that polymorphonuclear neutrophils (PMN) contribute to the pathogenesis of UC. This study aims to identify antigen (Ag)-specific PMNs and investigate their role in UC relapse. In this study, the correlation between PMN activities and UC relapse was assessed in a group of UC patients. A UC mouse model was developed to expand the findings of UC patient study. The results showed that a positive correlation was detected between the high PMN activities and the food Ag-specific IgG (sIgG) amounts in colon biopsies of UC patients. UC patient-derived Ag-specific PMNs could be activated upon exposure to food specific Ag (sAg). The Ag/FcγRI complexes were detected on the surface of PMNs in UC patients. Re-exposure of sensitized PMNs to sAg triggered PMN activation and induced UC-like inflammation in the mouse colon. We conclude that FcγRI play a critical role in UC relapse. Inhibition of FcγRI can efficiently inhibits experimental UC. This article is protected by copyright. All rights reserved.