Immunoglobulin G4 immunostaining of gastric, duodenal, or colonic biopsies is not helpful for the diagnosis of autoimmune pancreatitis

Abstract

Background & aims: The aim of this study was to evaluate the specificity of the infiltration of digestive tract mucosa by immunoglobulin (Ig) G4-positive plasma cells in patients with autoimmune pancreatitis (AIP), as compared with normal or inflammatory mucosa.

Methods: Plasma cell infiltration, CD138 and IgG4 immunostaining of digestive biopsies were compared in 4 groups of patients: AIP type 1 (n = 19); AIP type 2 (n = 4) with inflammatory bowel disease (IBD); IBD without pancreatic disorders (n = 20); and controls (n = 26).

Results: With AIP type 1 versus controls, more plasma cells were present in the gastric mucosa of AIP (P = .02) without difference concerning IgG4+ plasma cells at any biopsy site. With AIP type 1 versus IBD, colonic mucosa was more often abnormal (P = .004), and more CD138 (P = .02) and IgG4 plasma cells (P = .0002) were counted in the colon biopsies of IBD. With AIP type 2 versus IBD, no difference for plasma cell and IgG4 infiltration was found.

Conclusions: IgG4-positive plasma cells are not more numerous in the digestive mucosa of AIP patients than in controls, but they are more abundant in the colon of IBD patients than in AIP patients.