[542] Quantitative Analysis of Intramucosal Mast Cells in Inflammatory Bowel Disease (IBD) and Symptomatic Non-IBD Patients with Histologically Uninflamed Colon Biopsies

CE Aguilar, D Dhall, F Chung, HL Wang. Cedars-Sinai Medical Center, Los Angeles, CA

Background: Increased intestinal mast cell count, as recently proposed by >20 mast cells per high power field (HPF), has been reported in patients with irritable bowel syndrome (IBS). Mast cell activation has also been implicated in IBD but whether the number of intramucosal mast cells is quantitatively increased remains controversial. We aimed to study the density of mast cells in histologically unremarkable or uninflamed colon biopsies obtained from IBD and non-IBD patients to look for any particular disease group(s) that might show an increased mast cell count.
Design: Random colon mucosal biopsies (n=118) showing no histopathologic abnormality (including quiescent IBD) were immunostained with CD117 (c-kit) and mast cell tryptase (MCT). Intact mast cells with an identifiable nucleus were quantified in three 400X fields in areas with the highest density for each stain. The mean values of each case were analyzed according to patient groups based on clinical history and endoscopic findings.
Results: Both CD117 and MCT stains were equally sensitive in detecting intramucosal mast cells with similar mean counts (P=0.864), and thus only CD117 results were subjected to subsequent analyses. The overall mast cell counts in all biopsies ranged from 2-31 per HPF (mean: 16.96.2; median: 17). No significant difference was demonstrated between patients with IBD (mean=15.6 5.6; n= 47) vs non-IBD (mean=17.86.4; n=71; P=0.060), Crohn (mean=14.16.0; n=21) vs ulcerative colitis (mean=17.05.1; n=25; P=0.084), non-IBD with diarrhea (mean=18.36.1; n=33) vs without diarrhea (mean=17.46.8; n=38; P=0.550), non-IBD with abdominal pain (mean=17.16.0; n=19) vs without abdominal pain (mean=18.16.6; n=52; P=0.567). Thirty-six biopsies (30.5%) showed >20 mast cells/HPF, which appeared to be equally distributed among various patient groups (23.4% in IBD, 36.4% in non-IBD with diarrhea, and 34.2% in non-IBD without diarrhea; P0.221).
Conclusions: There is no significant difference in the number of intramucosal mast cells in patients with or without IBD, diarrhea, or other digestive symptoms. Increased mast cell counts were observed in various patient groups with uninflamed colon biopsies, suggesting a nonspecific finding that may not be reliable in segregating patients with IBS.
Category: Gastrointestinal

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 67, Wednesday Morning