Differences between the early and advanced stages of rheumatoid arthritis in the expression of EDA-containing fibronectin

In the present study the expression of alternatively spliced synovial EDA-containing FN (EDA-FN) was analyzed in plasma and synovial fluid samples of rheumatoid arthritis (RA) patients with from 2 months to 20 years disease duration. The patient samples were divided into groups: those with early, established, and late progressive radiographic changes as well as those with different disease activity established by a CRP concentration. The expression of EDA-FN was determined by sandwich-type ELISA using a specific anti-EDA monoclonal antibody. The relative amount of EDA-FN in synovial fluid, but not in plasma samples, was significantly lower in the early RA group than in established and late RA. In contrast, its level did not correlate with the CRP concentration. Synovial EDA-FN might be used as a supplemented marker of early RA.