Colonic Mucosal Infiltration of IgG4 Plasma Cells and Ulcerative Colitis: Determinant of Presence, Activity, Extension, and Duration of Disease.

BACKGROUND Infiltration of IgG4 positive plasma cells has been detected in the colonic mucosa of patients with ulcerative colitis (UC). The aim of the study was to investigate the association between colonic mucosal infiltration of IgG4 plasma cells and the presence, activity, extension, and duration of UC. METHODS In this case-control study (2009-2014), 102 subjects (84 with UC/18 controls) were enrolled. Clinical records and rectosigmoid biopsies of UC patients were selected, and biopsies were stained with IgG4 monoclonal antibodies. IgG4 positive plasma cells were counted by a single pathologist. RESULTS Amongst 84 patients with UC, 73.8% had UC without primary sclerosing cholangitis (PSC), and 26.2% had UC with PSC. IgG4 plasma cells were seen in 35 (41.7%) patients with UC and 0% of controls (p = 0.001). The mean amount of IgG4 containing plasma cells was significantly different between active and inactive patients with UC, although it was not significantly different between UC patients with and without PSC. The presence of IgG4 infiltration was significantly associated with the extension and duration of the disease. Furthermore, IgG4 count had a sensitivity/specificity of 78.6%/83.3% for the diagnosis of UC. CONCLUSION Our study revealed the diagnostic role of IgG4 plasma cells in the colonic mucosa of patients with UC and its association with activity, extension, and duration of disease.