In autoimmune diseases such as rheumatoid arthritis (RA), we showed that TGF-β and other proinflammatory cytokines enhanced CXCL13 production by CD4+ T cells and that CXCL13-producing CD4+ T cells had an important role in the formation of TLS (16, 17). Here, CXCL13 is linked to rheumatoid arthritis.