Background/Aims: We investigated the mRNA expression of spectrum of cytokines in the colonic mucosa in inflammatory bowel disease (IBD). Methods: The expression of cytokine gene was evaluated by using the reverse transcription-polymerase chain reaction and the radioactivity of amplified cDNA standardized by coamplified β-actin cDNA. Results: Crohn’s disease and ulcerative colitis showed significantly increased expression of IL-1β, IL-6, IL-8 and TNF-α mRNA as compared with controls (p < 0.05). Conclusion: Proinflammatory cytokines such as IL-1β, IL-6, IL-8 and TNF-α are closely involved in the immune abnormalities of inflammatory mucosal lesions in IBD.

Interleukin-8 (IL-8) is a peptide which induces not only chemotaxis of neutrophils but also the release of reactive oxygenmetabolites from the neutrophils. There are few reports whichclarify the relationships between IL-8 and mucosal infiltration of neutrophils or reactive oxygen metabolites produced by neutrophils in the colonic mucosa of ulcerative colitis (UC). Biopsy specimens of colonic mucosa obtained from 26 patients with active UCand 21 patients with inactive UCwere studied in order to clarify the relationships amongthe inflammation factors in UC. Levels of IL-8 and myeloperoxidase in organ culture media of the biopsy specimens from active UC(measured by ELISA and EIA) were significantly higher than those from inactive UCand controls. Reactive oxygen metabolites of biopsy specimens in active UC(measured by luminol-dependent chemiluminescence) were also markedly increased compared to those in inactive UC and controls. The levels of IL-8 were closely correlated to luminol-dependent chemiluminescence or myeloperoxidase levels. However, the levels ofIL-8 and myeloperoxidase did not correlate with the grades of activity on colonoendoscopic findings. These findings suggest that IL-8 may play a role in the pathophysiology of UCbut it does not define the endoscopic activity grades of UC. (Internal Medicine 37: 253-258, 1998)