Ulcerative colitis (UC) is an immune disorder of the gastrointestinal tract which has been reported to be precipitated by interferon (IFN) therapy. We describe the results of a literature review of cases in which the development or exacerbation of UC was coincident with IFN and/or ribavirin (RIB) treatment for chronic hepatitis C. We summarized the studies on the effectiveness of IFN for UC or Crohn's disease, which were primarily carried out in Europe and the USA.
In the nine reported cases of UC exacerbation by IFN therapy in Japan, seven involved IFN-α, one involved IFN-α2b plus RIB, and the other involved IFN-β; thus cases induced by IFN-α were more common. The period between the initiation of IFN treatment and the development or exacerbation of UC varied widely among the reported cases (from 1 day to 4.5 years). The reports have all assumed a cause-and-effect correlation between IFN treatment and UC. However, although combination therapy of IFN and RIB has become widespread in Japan, UC development or exacerbation induced by IFN has not increased concurrently.
Conversely, numerous studies reporting the effectiveness of IFN for treating UC and Crohn's disease have been published in Europe and the USA. One reason for this finding may be the difference in the balance of T helper cell 1 and T helper cell 2 between populations.