In light of the well-established role of Th17 cells in RA pathogenesis, and in particular in the development of synovial germinal center-like structures, Jones et al. demonstrated that synovial IL-27 expression is more pronounced in germinal center-negative RA synovium compared to germinal center-positive RA synovium and OA synovium, and that it is inversely correlated to the expression of molecules involved in ectopic lymphoid neogenesis. The gene discussed is IL27; the disease is rheumatoid arthritis.