Tissue infiltration of IgG4+ plasma cells in symptomatic patients with ileal pouch-anal anastomosis.

BACKGROUND Inflammatory bowel disease (IBD) is reported to be associated with autoimmune pancreatitis. The aim of the study was to investigate serum IgG4 and tissue infiltration of IgG4+ plasma cells in symptomatic patients with ileal pouches. METHODS Ninety-seven consecutive persistent symptomatic patients with ileal pouches from our subspecialty Pouchitis Clinic from January to December 2010 were included in the study. Serum IgG4 was measured at the time of presentation. All patients underwent pouchoscopy with pouch biopsies immunostained for IgG4+ plasma cells. Patients with ≥10 per high-power field of IgG4+ plasma cells were considered positive for the stain. RESULTS Twenty-eight (28.9%) patients had positive IgG4 immunostaining of pouch and/or afferent limb biopsy, while the remaining 69 patients (71.1%) were IgG4 negative. Demographic and symptoms were similar between the two groups. The median serum IgG4 in the IgG4 positive group was 21.3 (interquartile range 0-41.3) mg/dL vs. 0 (interquartile range 0-18) in the IgG4 negative group. (p=0.04). On multivariate analysis, the Pouchitis Disease Activity Index (PDAI) endoscopy score in the pouch (odds ratio [OR] 1.66, 95% confidence interval [CI]: 1.21-2.29, p=0.002) and number of concomitant autoimmune disorders (OR 3.04, 95% CI: 1.22-7.53, p=0.017) were independent risk factors for the presence of IgG4+ plasma cell infiltration. CONCLUSIONS Increased IgG4+ plasma cells were found in 1/4 of IPAA patients with persistent symptoms. The presence of tissue infiltration of IgG4+ plasma cells appeared to be associated with chronic pouch inflammation and concurrent autoimmune disorders.