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P105. Active inflammation of the appendix in ulcerative colitis

T. Gardenbroek1, C. Buskens1, J. van Straalen2, G. van den Brink3, G. D'Haens3, W. Bemelman1, 1Academic Medical Center, Department of Surgery, Amsterdam, Netherlands, 2Academic Medical Center, Department of Clinical Chemistry, Amsterdam, Netherlands, 3Academic Medical Center, Department of Gastroenterology, Amsterdam, Netherlands

Background

Several studies suggest that the appendix plays a causative role in ulcerative colitis (UC). Nowadays, appendectomy is sometimes offered as experimental treatment in these patients. Some studies show histologically normal appendices in UC, whereas others suggest mucosal inflammation in the appendix comparable to the disease activity in the colon. The objective of this study was to analyse T cell infiltration in the appendices of UC patients undergoing colectomy and compare these to patients with Crohn's disease (CD), acute appendicitis and non-inflammatory controls.

Methods

The appendix was removed from the surgical resection specimen and flushed with 2cc of phosphate buffered saline. The number of CD4 and CD8 lymphocytes in the lavage fluid was determined by FACS analysis and the CD4/CD8 ratio was calculated. The appendix was histologically evaluated by assessing the degree of inflammation (mucosal, submucosal or transmural) and mucosal ulceration. In addition, slides were immunohistochemically stained for CD4 and CD8, and scored according to the number of positive cells per high power field (graded 1–4).

Results

Ten patients with UC, 8 with CD, 4 with appendicitis and 5 control patients (FAP or right sided colon cancer) were included. In UC patients all appendices appeared macroscopically normal, although at histological evaluation 7 patients showed mucosal based inflammation with lymphocyte infiltration. This differed from the more extensive infiltration of granulocytes and oedema in the mucosa and submucosa of CD patients and the transmural inflammation present in the macroscopically affected appendices of the appendicitis patients. No granulocytes or signs of inflammation were seen in the controls. Immunohistochemical staining showed extensive influx of CD4 lymphocytes (grade 3 or 4) in 6 UC patients, 7 CD patients, all appendicitis patients and none of the controls. CD4/CD8 ratio in the lavage fluid was determined in 22 patients. The median ratio of 4.7 in UC was increased compared to 2.7 in the control group (p = 0.06), but not significantly different from the ratio of 5.8 in the CD and 4 in the appendicitis group. In 82% of patients, a high CD4/CD8 ratio (ratio ≥3) correlated with increased influx of CD4 lymphocytes, confirming inflammation.

Conclusion

Despite a macroscopically normal appearance, the appendix shows increased numbers of CD4 lymphocytes in the mucosa in patients with UC. The CD4/ CD8 ratio in the lavage fluid can be used as a measure of this inflammatory process.