THE RATIONALE FOR FK-506 IN INFLAMMATORY BOWEL-DISEASE

FK 506 is a novel macrolide immunosuppressant which is more potent tha n cyclosporine. Recent evidence that cyclosporine has efficacy in the treatment of inflammatory bowel disease (IBD) led to the development o f a new protocol using FK 506. FK 506 has been shown to produce substa ntially greater survival in liver transplant patients than cyclosporin e, with fewer side effects. Inhibition of lymphocyte production of cyt okines interleukin (IL)-2, IL-3 and interferon gamma requires 10 to 10 0 times greater concentrations of cyclosporine than of FK 506. Rejecti on episodes are less frequent and side effects fewer in patients recei ving heart, kidney or liver transplants following treatment with FK 50 6 than with cyclosporine. Thus, the development of a new, potent immun osuppressive agent with a greater safety profile than cyclosporine pro vides a new opportunity to identify an effective therapy for patients with IBD resistant to corticosteroids.