ELEVATION OF INTERLEUKIN-6 IN INFLAMMATORY BOWEL-DISEASE IS MACROPHAGE-DEPENDENT AND EPITHELIAL CELL-DEPENDENT

Local interleukin-6 (IL-6) activity was studied using colonic mucosal tissues in inflammatory bowel disease (IBD) and inflammatory control p atients. Active IBD specimens exhibited significantly higher IL-6 acti vity than control specimens in both cultures of isolated lamina propri a mononuclear cells (LPMC) and mucosal tissues with an increased numbe r of IL-6-producing cells. However, the activity in inactive IBD or in flammatory controls did not differ from controls. Northern blot analys is demonstrated IL-6 messenger RNA in LPMC and colonic epithelial cell s isolated from active IBD specimens but not in control cells. Further more, immunofluorescent microscopic study of active IBD specimens show ed more conspicuous staining of IL-6 in infiltrating LPMC (mostly CD68 (+) cells) and colonic epithelial cells. These results suggest that el evation of local IL-6 activity may be a characteristic feature of acti ve IBD and both macrophages and colonic epithelial cells are the major cell types responsible for this phenomenon.