CD14 and rheumatoid arthritis: Soluble CD14 is produced by HepG2 hepatoma cells and peripheral blood mononuclear cells on IL-6 stimulation [10,20], suggesting that a positive feedback loop could exist whereby sCD14 causes RA-FLS inflammation, and the IL-6 produced by activated RA-FLS promotes further sCD14 production by hepatocytes and monocytes.