Background: Previous studies have shown that irritable bowel syndrome declines with age and is more common in women. Recent reports suggest that some diarrhoea predominant irritable bowel syndrome patients have low-grade inflammation with increased numbers of mucosal T lymphocytes, 5-hydroxytryptamine (5-HT) containing enteroendocrine cells and mast cells.
Objective: To determine whether there are age or gender-related changes in mucosal T lymphocytes, mast cells or enteroendocrine cells which might explain these findings.
Methods: Forty healthy volunteers (20 subjects below 55 years of age and 20 above 55 years) free from gastro-intestinal symptoms or disease answered detailed bowel symptom questionnaires and underwent sigmoidoscopy, rectal biopsy and colonic transit measurement. Biopsies were immunostained and quantified for lamina propria and intra-epithelial T lymphocytes, mast cells and 5-HT and peptide YY enteroendocrine cells.
Results: There was a reduction in lamina propria T lymphocyte counts (P = 0.018), crypt intra-epithelial T lymphocytes (P = 0.014) and mast cells (P = 0.02) in the > 55 year group. Enteroendocrine cell numbers did not decline with age and were not related to colonic transit. There were no gender differences between any of the cells quantified.
Conclusions: Lymphocyte and mast cell numbers decline with age in normal large bowel mucosa. Reduced numbers of mucosal inflammatory cells may influence the low-grade inflammatory response to luminal antigens and contribute to the reduction of irritable bowel syndrome observed in older subjects.