ABSTRACT
Multiple sclerosis [MS] is a CD4[+] T cell-mediated autoimmune disease affecting the central nervous system [CNS]. It was previously believed that Th1 cells were pathogenic T cells in experimental autoimmune encephalomyelitis [EAE]. However, the functional role of Th1 cells in EAE has been reconsidered upon the discovery of IL-17-producing T cells which are consider as dominant effectors for inducing autoimmune tissue inflammation. The objective of this study was to assess the role of IL-17A and IL-17F in MS pathogenesis. We evaluated mRNA expression of IL-17A and IL-17F in thirty-five Iranian patients with relapsing-remitting MS [RRMS] and twenty-five healthy controls by Quantitative Real Time PCR. The results of this study showed a twenty-fold increase in the expression of IL-17A mRNA in MS patients compared to the control group [p < 0.0001]. IL-17F mRNA expression in MS patients was thirty three-times greater than control group [p = 0.0008]. IL-17A mRNA expression in periphery was positively correlated with expression of IL-17F transcripts in MS patients and controls [p < 0.01 and p < 0.05, respectively]. These results indicate the critical role of Th17- mediated cytokines in development of MS which classically has been considered as a Th1-mediated disorder. The results of this study showed, for the first time, the importance of IL-17F in MS immunopathogenesis