Inhibition of passive localized experimental allergic encephalomyelitis by interferon

Recently it has been reported that interferon (IFN) suppresses experimental allergic encephalomyelitis (EAE) in actively immunized Lewis rats. In the present study the effect of IFN on a localized form of passively transferred EAE has been investigated. Localization and acceleration of the disease was obtained by injection of EAE lymph node cells into rats which had, 3 days previously, been prepared with a thermal brain injury. Within 24 h of cell transfer perivenular lymphocytic infiltrates (EAE lesions) were observed in the brain. Administration of IFN (40,000 U/kg) right after EAE lymph node cell injection resulted in a significant reduction or elimination of EAE lesions. The possibility that IFN is acting exclusively on the afferent arc is eliminated, and the results suggest that IFN may be acting, although not solely, through modulations of components of the efferent arc. IFN was equally effective in suppressing EAE in adrenalectomized animals. This demonstrates that the immunosuppressive effects observed in this study are not due to endogenously produced corticosteroids.