Investigation of neutrophil migration into the gut by cytology of whole gut lavage fluid

Objective: Radiolabelling studies have shown that neutrophils migrate into the gut lumen in inflammatory intestinal diseases. We aimed to establish whether whole gut lavage fluid can be used to investigate intestinal neutrophilia. Design: A prospective single centre study comparing inflammatory bowel disease patients, patients with other gastrointestinal diseases and normal controls. Methods: Gut lavage with a polyethylene glycol-based solution was performed in 56 patients (29 with inflammatory bowel disease). Gut lavage fluid samples were collected when the rectal effluent was clear. Cells were then separated by density gradient centrifugation, counted, and cytospin preparations examined. Results: High cell counts (> 3.7x10⁵/ml), predominantly neutrophils, were present in 12 out of 29 inflammatory bowel disease patients and in two out of 27 others. High cell counts and luminal neutrophilia characterized active ulcerative colitis and active colonic Crohn's disease, but not active small bowel Crohn's disease, or inactive disease. Conclusion: Whole gut lavage fluid samples can be used to investigate luminal inflammatory cells. We observed previously unrecognized differences between small bowel and colonic Crohn's disease using this method. The mechanisms of neutrophil migration into the gut lumen may differ with disease distribution.