Expression of lymphocyte-endothelial receptor-ligand pairs, alpha 4 beta 7/MAdCAM-1 and OX40/OX40 ligand in the colon and jejunum of patients with inflammatory bowel disease

Background-The interaction between leucocytes and vascular endothelial cell s is essential for leucocyte migration into inflammatory sites. Aims-To study the local expression of the pairs of complementary molecules, alpha 4 beta 7/mucosal addressin cell adhesion molecule (MAdCAM-1) and OX4 0/OX40 ligand in the lamina propria of the colon and jejunum of patients wi th inflammatory bowel disease. Methods-Ten patients with active ulcerative colitis (UC), nine with active Crohn's disease (CD), and seven irritable bowel syndrome (IBS) controls wer e submitted to endoscopic and peroral jejunal biopsies. Specimens were immu nostained by indirect alkaline phosphatase using antibodies against: CD3, i ntercellular adhesion molecule (ICAM) 1, alpha 4 beta 7, MAdCAM-1, and OX40 . An OX40-mouse-IgG fusion protein was used to detect OX40 ligand on frozen sections. Immunohistological analysis was carried out by optical microscop y using a computer assisted image analyser. Results-Colonic lamina propria of patients with CD and UC showed increased density of CD3+, alpha 4 beta 7+, and OX40+ cells compared with IBS control s. ICAM-1, MAdCAM-1, and OX40 ligand positive vessels were also increased c ompared with IBS controls. No significant difference was found in the densi ty of any of these cells in the jejunal mucosa of patients compared with IB S controls. Conclusions-The expression of MAdCAM-1 and OX40 ligand on gut: endothelial and OX40+ cells is increased in sites of mucosal inflammation in patients w ith inflammatory bowel disease. No evidence was found for increased lamina propria T cells or increased vascular adhesion molecule expression in the p roximal intestine of patients with distal inflammatory bowel disease.