IL21 and synovial sarcoma: Circulating IL-21-producing CXCR5+ICOS+PD-1+ (figure 1G, H) but not total CXCR5+ICOS+PD-1+ or IFN-γ producing Tfh-cells (online supplementary figure S2F–H) were higher in patients with SS with anti-Ro/SSA and anti-La/SSB autoantibodies.