Adoptive transfer from interferon-alpha-fed mice is associated with inhibition of active experimental autoimmune encephalomyelitis by decreasing recipient tumor necrosis factor-alpha secretion.

Ingested type I interferon (IFN) suppresses clinical relapse in murine chronic experimental autoimmune encephalomyelitis (EAE), inhibits clinical attacks more effectively than subcutaneous doses, and decreases the adoptive transfer of EAE. To determine whether splenocytes from IFN-fed donors were "suppressor-like" populations, donor SJL/J mice were immunized and fed with mock IFN-alpha or with IFN-alpha every other day for at least 4 weeks after initial clinical attack. Recipients of adoptively transferred CD8+ T cells from mock IFN-alpha-fed donors showed no clinical improvement of clinical disease compared with actively immunized controls. In contrast, recipients of adoptively transferred CD8+ T cells from IFN-alpha-fed donors showed decreased clinical disease compared with recipients of mock IFN-alpha-fed CD8+ T cells. To evaluate the mechanism of protection by donor CD8+ T cells and to determine if ingested IFN-alpha activates natural immunomodulatory cell populations, the authors used the acute EAE model and naïve-fed donor animals as sources of T cells and CD8+ T cells. Con A-activated spleen T cells from naïve nonimmunized mock IFN-alpha-fed donors inhibited actively induced disease and showed decreased recipient TNF-alpha secretion compared with recipients of T cells from mock IFN-fed mice. Donor activated spleen CD8+ T cells from naïve nonimmunized IFN-alpha-fed animals suppressed actively induced EAE in recipients and showed decreased IFN-gamma and TNF-alpha proinflammatory secretion. Decreased recipient TNF-alpha secretion correlates best with the disease protection from IFN-fed T and CD8+ T cells.