Patients with RA had lower frequencies of circulating CCR6+CXCR3−Th17, CCR6+CXCR3+Th1/17 [12] and of CXCR5+ICOS+Tfh cells [13] as compared to patients with OA (Fig. 2a), and the reduction in Th1/17 and Th17 cells was statistically significant. This evidence concerns the gene ICOS and rheumatoid arthritis.