Kinetics of IFN-γ and IL-17 expression and production in active experimental autoimmune encephalomyelitis in Dark Agouti rats

Interferon-γ (IFN-γ) and interleukin-17 (IL-17) have been involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE). We have carried out a follow-up study of the expression and production of these cytokines, as well as of cells expressing these cytokines during the course of active EAE in Dark Agouti (DA) rats. As a result, IL-17, but not IFN-γ expression and production had the peak value in draining lymph nodes (DLN) during the induction phase of the disease, and in spinal cords (SC) at the onset of clinical signs of the disease, and then declined toward the resolution of the disease. Also, a significant proportion of IFN-γ/IL-17 double-positive cells was observed in SC of DA rats in active EAE. Importantly, the highest proportion of IL-17 single positive and double-positive cells, but not of IFN-γ single positive cells, was observed at the onset of the disease. The observed difference in the kinetics of IFN-γ and IL-17 expression during active EAE in DA rats suggests different roles these cytokines might have in the pathogenesis of the disease.