Decreased serum levels of interleukin-35 among multiple sclerosis patients may be related to disease progression.

The regulatory role of interleukin (IL) -35 in the immunopathogenesis of multiple sclerosis (MS) is suggested in very few studies. We aimed to measure serum levels of IL-35 among clinically isolated syndrome (CIS) and relapsing-remitting MS (RRMS) patients and evaluate the associations between this cytokine and the disease clinical course. This cross-sectional study was conducted during 2017 in a referral university clinic. Forty patients and 40 healthy controls were included in the study. The level of IL-35 in the serum of all subjects was determined by ELISA. Serum level of IL-35 was reduced (p = 0.003) in RRMS in comparison with healthy controls. Moreover, the mean serum level of IL-35 among new cases (diagnosed within the 6 months prior to the study) decreased compared to healthy controls but it was not statistically significant (P=0.059). The mean serum level of IL-35 was significantly higher in new cases compared with other cases (p=0.048). Overall, we found decreased serum level of IL-35 among RRMS patients compared to the healthy controls. Our finding provides a view of the possible role of IL-35 in MS pathogenesis and the potential therapeutic targets.