The Significance of IGG4 in Inflammatory Bowel Disease.
Renu K Virk, Gregory Y Lauwers, Vikram Deshpande. UMass Memorial Medical Center, Worcester, MA; Massachusetts General Hospital, Boston
Background: IgG4 has emerged as a diagnostic marker for autoimmune pancreatitis (AIP). Several prior studies have noted an elevated risk of inflammatory bowel disease (IBD) in patients with AIP, and the majority of these patients have ulcerative colitis (UC). Based on this data, and the observations that both UC and AIP show robust Th2 type responses, we hypothesized that IgG4 stain may assist in distinguishing UC from Crohn's disease (CD), the latter being associated with a Th1/Th17 CD4 response.
Design: We evaluated consecutive patients with UC (n= 42), and CD (n=34). The biopsies we evaluated were obtained at their initial presentation and prior to therapy. The median follow-up of this cohort was 52 months. Four cases of AIP with IBD were also evaluated, as were 16 cases of lymphocytic/collagenous (microscopic colitis, MC). The inflammatory activity in these biopsies was graded as 1 (cryptitis only), 2 (crypt abscesses), and 3 (ulceration). IgG4 and IgG immunostains were performed. A single high power field (HPF) with the highest number of IgG4 positive plasma cells was enumerated. The same HPF was located on the IgG stain and the number of immunoreactive plasma cells counted.
Results: UC cases showed significantly more IgG4 positive plasma cells than CD (p<0.0001) and also showed higher IgG4 to IgG ratio (p=0.001).
|Disease||Mean IgG4/HPF (median/SD)||Mean IgG4/IgG ratio|
|Ulcerative colitis||10.6 (6/13)||0.2|
|Crohn's disease||2.1 (1/2.7)||0.06|