[The von Willebrand factor antigen in patients with rheumatoid arthritis: a method for its determination and the clinical significance].

The data are available on concentrations of Willebrand factor antigen (FVIII Ag) in 43 patients with rheumatoid arthritis (RA), 19 patients with livedo vasculitis (LV) and 56 donors. The measurements were made with solid-phase enzyme immunoassay. RA patients were found to display significantly higher concentrations of FVIII Ag (1.88 +/- 0.17 IU/ml) versus donors (1.06 +/- 0.05 IU/ml, p < 0.001) and LV patients (1.08 +/- 0.09 IU/ml, p < 0.001). No significant differences existed between FVIII Ag concentrations in LV patients and donors (p > 0.05). In 12 (28%) out of 43 RA patients FVIII Ag levels rose to 3 standard deviations from the mean in donors. Hyperproduction of FVIII Ag was associated with skin vasculitis symptoms in RA patients (p = 0.0004), more frequent occurrence of antinuclear factor (p = 0.02). Elevated concentrations of FVIII Ag did not relate to other extraarticular RA symptoms and general rheumatic inflammation, X-ray stage, RF titer, cryoglobulins, enhanced ESR, C-reactive protein.