IL9 and rheumatoid arthritis: Analysis of intracellular IL-9, IFNγ, IL-17 production, of CCR6 expression, IL-9R expression or of Ki67 in separated naive and non-naive CD4+ T cells before cell culture did not show any significant difference between RA and HD except for IFNγ-production which was higher in the naive fraction of HD (Figure 1 and Supplementary Figure 2).