Alternatively spliced EDA-containing fibronectin in synovial fluid as a predictor of rheumatoid joint destruction

Objectives. Fibronectin containing the EDA region (EDA (+) Fn), a molecule important for rheumatoid joint destruction, was measured in relation to the progression of joint destruction in rheumatoid arthritis (RA). Methods. Total Fn and EDA (+) Fn were measured by ELISA, and the concentrat ions of Fn in plasma and synovial fluid were compared prospectively for 2 y r with the progression of joint destruction in 41 knee joints of 37 patient s with RA. The extent of joint destruction was assessed by the Larsen score and joint space narrowing in X-ray films taken before and 2 yr after measu rement of EDA (+) Fn. Results. The concentration of synovial fluid EDA (+) Fn showed a positive c orrelation with the progression of joint destruction in RA (r = 0.78). Whil e total Fn in synovial fluid also showed a correlation with joint destructi on (r = 0.54), total Fn and EDA (+) Fn in plasma showed no correlation with joint destruction. The concentration of synovial fluid EDA (+) Fn was sign ificantly higher in patients who underwent joint replacement after the meas urement of EDA-Fn than in those who did not receive surgery (P < 0.029). Conclusion. Synovial fluid EDA (+) Fn can be a predictor of subsequent join t destruction in RA.