Upregulation of IL-17, but not of IL-9, in circulating cells of CIS and relapsing MS patients. Impact of corticosteroid therapy on the cytokine network.

The concomitant production of IL-17A and IL-9, both Th17 cytokines, has not been compared in MS patients. We show that IL-17A but not IL-9 expression by CD3(+) cells was increased during a MS relapse. Co-expression of IL-17A and IL-9 was marginal. In addition to Th1 and Th2 cytokines, IL-17A, IL-6 and IL-23p19 were down-regulated by ivMP, but Foxp3 was not, while an increase in IL-10, TGF-ß1 and IL-27p28 mRNA was observed. This change in the Th17, Treg and IL-10 balance could be an additional mechanism by which corticosteroids shorten the duration of a MS relapse and promote recovery.