CIRCULATING NEUTROPHILS FROM PATIENTS WITH ULCERATIVE-COLITIS HAVE A NORMAL RESPIRATORY BURST

The hallmark of ulcerative colitis is a diffuse infiltration of neutro phils from the circulation into the colonic mucosa. The underlying mec hanism for neutrophil tissue infiltration is unknown. One possible hyp othesis is abnormal circulating neutrophils. This hypothesis has been previously tested with conflicting results. The aim of our study was t o re-evaluate circulating neutrophil function in the absence of severa l possible confounding factors. To this end, we measured the respirato ry burst of circulating neutrophils in response to two different stimu li by chemiluminescence in patients with active and inactive ulcerativ e colitis being off all medications. Our results show no significant d ifference between ulcerative colitis patients and controls in peak che miluminescence, area-under-the-curve and time to peak comparisons. How ever, 27% of patients with active ulcerative colitis had an abnormally elevated chemiluminescence to stimuli. In addition, no correlations w ere seen between disease activity and peak chemiluminescence. Thus cir culating neutrophils in the majority of patients with ulcerative colit is do not appear to be either ''primed'' or hyperactive. This may sugg est the presence of local colonic factors that lead to neutrophil tiss ue infiltration and activation.