P074 Association of colonic mucosal infiltration of IgG4 plasma cells with ulcerative colitis activity and presence of primary sclerosing cholangitis
F. Alborzi*1, Z. Azizi2, N. Ebrahimi Daryani3, F. Azmude Ardalan3, N. Aletaha3, R. Taslimi3, N. Roshan3
1Tehran University of Medical Science, Gastrenterology, Tehran, Iran, Islamic Republic of, 2Iran University of Medical Science, Tehran, Iran, Islamic Republic of, 3Tehran University of Medical Science, Tehran, Iran, Islamic Republic of
Although infiltration of IgG4 positive plasma cells is detected in the colonic mucosa of ulcerative colitis patients, the real role of this antibody is unclear.In this study the association of colonic mucosal infiltration with IgG4secreting plasmacells, activity of disease, and presence of primary sclerosing cholangitis (PSC) was determined.
In this cross-sectional study, 102 subjects, 84 UC patients and 18 controls, were enrolled. Clinical records and rectosigmoid biopsies of UC patients in Imam Khomeini Hospital, Tehran, Iran, from 2009 to 2014, were selected, and biopsies were stained with IgG4 monoclonal antibody. IgG4 positive plasma cells were counted by a single pathologist, and the number of IgG4 laden plasma cells more than 10 was considered significant. Statistical analyses were performed using SPSS18, and p-value < 0.05 was considered statistically significant.
Amongst 84 UC patients, 73.8% were UC without PSC (67.7% active, 32.3% inactive) and 26.2% UCPSC (50%active, 50% inactive). None of our cases had evidence of AIP.The presence of IgG4 plasma cells was seen in 35 (41.7%) of 84 of UC patients and was statistically significant compared with 0% in the control group (p-value 0.001).The mean amount of IgG4 containing plasma cells was different between active and inactive UC groups (p-value 0.001).The presence of significant IgG4 infiltration was associated with extension and duration of disease (p-value 0.001), and not associated with the degree of inflammation (p-value 0.268). IgG4 count had sensitivity and specificity of 78.6 and 83.3% and 84.9 and 87.8% for diagnosis of UC from control group and determining disease activity, respectively.
Our study revealed that a portion of active UC cases independent from concurrent PSC have significant infiltration of IgG4 plasma cells in their colonic mucosa. The presence of tissue IgG4 was not related to AIP. These findings suggest other mechanisms for the role of IgG4 in pathogenesis of UC. Further studies are needed to explore the significance of IgG4 in UC.