CXCL8 and rheumatoid arthritis: As fibroblast-like synoviocytes themselves expressed CD40 and responded to CD40L to produce IL-6, IL-8 and MCP-1(monocyte chemoattractant protein-1) [54-56], these cells would be activated both directly and indirectly by CD40L-expressing T cells in the synovial tissue of RA patients.