Leukotriene B₄ ω-hydroxylase activity in polymorphonuclear leukocytes from patients with inflammatory bowel disease

ω-oxidation is regarded as the major pathway for the catabolism of leukotriene B₄ (LTB₄). To determine how LTB₄ ω-hydroxylase is modulated in inflammatory bowel disease, we investigated the kinetic characteristics of this enzyme in 10 patients with Crohn's disease (CD), nine with ulcerative colitis (UC) and eight healthy control subjects. After incubating polymorphonuclear leukocytes with various concentrations of ³H-labeled LTB₄, ω-oxidation products were serapated by high performance liquid chromatography (HPLC) and the radioactivity was measured by a liquid scintilation counter. The apparent Vmax values were significantly higher in both disease than in healthy control subjects, although the difference between CD and UC was insignificant. There was no difference in the apparent Km values. And the Vmax Km ratios of patients with CD were significantly higher than that of healthy control subjects. It is suggested that LTB₄ metabolism is activated in inflammatory bowel disease (IBD) and that the modulation of this enzyme activity has an important role in the pathogenesis of inflammatory bowel disease.