Comparison of arachidonic acid metabolism in nasal polyps and eosinophils

Nasal polyp tissue is characterized by its frequent infiltration by large numbers of eosinophils. We have studied the metabolism of 14C-labeled arachidonic acid by both nasal polyp tissue and by eosinophils. The major metabolite produced by both is 15-hydroxyeicosatetraenoic acid (HETE) with lesser amounts of 12-HETE. No cyclooxygenase pathway products were found. The 15-lipoxygenase activity of nasal polyps averages 30 times that of normal nasal mucosa or chronically inflamed sinus mucosa. Nasal polyps which contained significant numbers of eosinophils averaged 7 times the 15-lipoxygenase activity of nasal polyps without eosinophilia. Thus, eosinophils appear to be a major source of 15-lipoxygenase activity in nasal polyps.