ADHESION MOLECULES IN INFLAMMATORY BOWEL-DISEASE

The ability of leucocytes to adhere to endothelium is essential for le ucocyte migration into inflammatory sites. Some of these adhesion mole cules are released from the cell surface and can be detected in serum, The soluble adhesion molecules intercellular adhesion molecule 1 (ICA M-1), E selectin, and vascular cell adhesion molecule 1 (VCAM-1) were studied in the serum of patients with Crohn's disease, ulcerative coli tis, and healthy controls. A second blood sample was taken from patien ts with active disease after one month of treatment and a third two mo nths after remission was achieved. Tissue expression of the same adhes ion molecules was studied by immunohistology. Circulating VCAM-1 conce ntrations significantly higher in patients active ulcerative colitis ( n=11, median=165 U/ml) compared with patients with inactive ulcerative colitis (n=10, median=117 U/ml, p<0.005), active Crohn's disease (n=1 2, median=124 U/ml, p<0.02), and controls (n=90, median=50 U/ml, p<0.0 001). Within each disease group there were no significant differences in E selectin or ICAM-1 concentrations between the active and inactive states, however, patients with active Crohn's disease had significant ly higher ICAM-1 concentrations (n=12, median=273 ng/ml) than controls (n=28, median=168, p<0.003). VCAM-1 concentrations fell significantly from pretreatment values to remission in active ulcerative colitis (p <0.1). In Crohn's disease there was a significant fall in ICAM-1 both during treatment (p<0.01) and two months after remission (p<0.02). Vas cular expression of ICAM-1 occurred more often and was more intense in inflamed tissue sections from patients The General with ulcerative co litis and Crohn's disease Infirmary, Leeds than from controls. Vascula r labelling with antibody to E selectin also occurred more often in pa tients with active inflammatory bowel disease. In conclusion, increase d circulating concentrations of selected adhesion molecules are associ ated with inflammatory bowel disease. There is also evidence of local upregulation, particularly of ICAM-1. Differential expression of adhes ion molecules in tissue may play a part in the initiation of leucocyte migration and local inflammation; the function of circulating adhesio n molecules is unknown, but may play a physiological part in blocking adhesion.