Production of TNF-α, IL-6, IL-8, histamine and other inflammatory mediators by the activated mast cells could drive synovitis in RA [9,10], and it has been shown that mice deficient in mast cell activation were resistant to the induction of arthritis in the K/BXN model of rheumatoid arthritis [11]. Here, CXCL8 is linked to arthritic joint disease.