IL21 and rheumatoid arthritis: BCL6 expression has been shown to be sustained by IL-6 signaling in patients with rheumatoid arthritis (RA), and specific targeting of IL-6 using tocilizumab in patients with RA results in a significant reduction of circulating Tfh cells; IL-21 production by Tfh cells was also correlated with reduced expression of antibody-producing plasmablasts [21].