Comparison of leukocyte excretion and blood loss in inflammatory disease of the bowel.

Clinical relapse of inflammatory bowel disease is characterised by increased neutrophil migration into the intestine. The site of the neutrophil chemoattractant(s), whether luminal or mucosal, may be important since, on contact with a chemoattractant, neutrophils cause indiscriminate damage to their immediate surroundings by generating reactive oxygen species and by lysosomal enzyme release. If this happens within the mucosa, inflammation should correlate significantly with tissue damage as assessed by bleeding, but if it occurs within the intestinal lumen, the inflammation would be disproportionately greater than the bleeding such as is seen in classical exudation. Intestinal inflammation and bleeding were quantitated with the simultaneous use of indium-111 labelled neutrophils (four day faecal excretion of indium-111) and chromium-51 labelled red cells in patients with ulcerative colitis (n = 12), Crohn's disease (n = 15), and NSAID induced enteropathy (n = 34). Intestinal inflammation and blood loss correlated significantly (Spearman) in patients with ulcerative colitis (20.3% v 6.5 ml/d (median) r: 0.85, p < 0.001) and NSAiD enteropathy (1.6% v 1.9 ml/d, r: 0.60, p < 0.01) but not in Crohn's disease (17.0% v 2.1 ml/d, r: 0.38, p > 0.1). For a given indium-111 excretion, patients with ulcerative colitis had significantly greater (p < 0.01) blood loss than patients with Crohn's disease. These results suggest that the predominant site of neutrophil chemoattractants may be within the mucosa in ulcerative colitis and NSAID enteropathy and within the lumen in Crohn's disease.