The preventive effect of oral administration of type I interferon on collagen-induced arthritis in rats.

We investigated the effect of oral administration of type I interferon (IFN) on an autoimmune disease collagen-induced arthritis (CIA) in rats that was induced by immunization with type II collagen (CII). The results showed that the oral administration of IFN before immunization with CII significantly suppressed the development of CIA. Delayed type hypersensitivity, in vitro proliferative responses of lymph node cells to CII, and IL-2 production were also inhibited by the fed cytokine. The serum from IFN-fed animals downregulated the development of CIA and proliferative responses to CII. In contrast, IFN given orally after the onset of CIA failed to affect the proliferation of T cells to CII as well as the progression of the disease. There was a decrease in the production of anti-CII antibody in rats fed IFN before, but not after, immunization with CII. Thus, orally administered IFN may have preventive, but not therapeutic, effects on autoimmune inflammatory joint diseases.