To investigate whether serum levels of circulating cellular fibronectin (cFN) are increased in patients with rheumatoid arthritis (RA) complicated by vasculitis.
Levels of serum cFN were determined by an enzyme-linked immunosorbent assay (ELISA) in 26 RA patients with histologically proven vasculitis of recent onset (RV) and were compared to the levels in 47 RA patients with extraarticular manifestations of recent onset but no histological evidence of vasculitis (RA+), 43 patients with uncomplicated RA (RA-), 16 patients with systemic lupus erythematosus and active disease (SLE), 30 patients with active Crohn's disease (CD), 21 young healthy controls (yHC) and 17 elderly healthy controls (eHC). Plasma levels of cFN and von Willebrand factor antigen were also determined in the RA patients.
In RV patients, the median cFN level was significantly (P = 0.01) higher compared to that of RA+ patients, and was also significantly (P < 0.0000) higher compared to the cFN level in the RA-, SLE, CD, yHC and eHC groups. When compared to eHC, the cFN level was significantly higher in RA+ (P = 0.008); it was also higher in RA-, although not significantly (P = 0.42). 77% of the RV patients, 55% of the RA+ patients, and 37% of the RA-patients had a cFN level > 2 SD above the mean level for eHC. At an optimal cut-off titre the sensitivity of the cFN ELISA in discriminating RV patients from RA+ patients was 90%, the specificity was 46% and the accuracy was 68%. Plasma levels of cFN correlated significantly (r = 0.62; P < 0.001) with the von Willebrand factor antigen levels.
Increased levels of serum cFN are present in patients with RA, and are frequently found in RA patients with extraarticular manifestations, particularly in those with vasculitis.