IL-27-producing CD14+ cells infiltrate inflamed joints of rheumatoid arthritis and regulate inflammation and chemotactic migration

► The IL-27 level in synovial fluid of RA is significantly higher than that of OA. ► IL-27 in RA joints is derived from CD14+ cells. ► IL-27+CD14+ cells significantly infiltrate into RA synovium. ► WSX-1 is ubiquitously expressed on RA synovium. ► IL-27 suppresses the production of IL-6 or CCL20 from RA fibroblast-like synoviocytes.