To determine if differential glycosylation of fibronectin (Fn) in inflammatory synovial fluid (SF) included expression of an oncofetal epitope (Onf Fn) heretofore detected only on Fn derived from embryonal or neoplastic tissue.
Fn were purified from plasma, SF and synoviocyte conditioned medium by affinity chromatography and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting utilizing a monoclonal antibody (FDC-6) specifically recognizing the Onf Fn.
The Onf Fn was not expressed on Fn isolated from normal or RA plasma but was strongly expressed on Fn from rheumatoid arthritis (RA) SF and to a lesser extent osteoarthritis SF. Onf Fn was also detected on Fn secreted by cultured RA synoviocytes.
Fn present in the SF but not plasma of patients with rheumatic disease contains an epitope previously thought to be restricted to Fn produced by embryonal or malignant tissue.