46. Increased eosinophils and mast cells in the irritable bowel syndrome

Abstract

Background Irritable bowel syndrome is a functional bowel disorder, the aetiopathogenesis of which has been poorly understood. It appears to be multifactorial and to involve altered gastrointestinal motor function, enhanced perception of visceral stimuli and psychosocial factors. Only a few studies have analysed the involvement of inflammatory cells in this condition. The aim of this study was to determine whether eosinophils and mast cells were increased in the colonic mucosa in irritable bowel syndrome compared to controls. Method Slides of 20 colonic biopsy materials of patients with irritable bowel syndrome who had endoscopically and histologically normal colonic mucosa were analysed. Twenty normal controls that had random colonic biopsies with macroscopic and histologic normal colonic mucosa and no organic or functional bowel disease were enrolled. Quantification of eosinophils and mast cells was performed on three non-overlapping fields of lamina propria at ×40 magnification. Eosinophil degranulation was semi-quantitatively estimated assessing the extent of free granules within the lamina propria. Results Among the total of 20 tests and 20 controls, the majority were females (75% and 65%, respectively). Diarrhoea predominant irritable bowel syndrome was the most common mode of presentation. Eosinophil number, degranulation and mast cell count were significantly high in colonic biopsies obtained from irritable bowel syndrome compared to control. Comment Elevated mast cells have already been reported in the colonic and ileal biopsies and there were a few proposals predicting the involvement of eosinophils in the pathogenesis of the irritable bowel syndrome. This study supports this finding and explains the possible neural – mast cell – eosinophil interaction in generating the symptoms of functional gastrointestinal disorders including irritable bowel syndrome.