Plasma and serum von Willebrand factor antigen concentrations in connective tissue disorders.

Concentrations of serum and plasma von Willebrand factor antigen were measured in over 200 patients with a variety of connective tissue diseases, and in control samples from over 200 asymptomatic individuals. This comprehensive study found the highest concentrations of von Willebrand factor antigen in patients with vasculitis, Sjögren's syndrome, Felty's syndrome, giant cell arteritis and polyarteritis nodosum. Raised values were also found in rheumatoid arthritis, systemic lupus erythematosus, polymyalgia rheumatica, systemic sclerosis, Raynaud's syndrome, Takayasu's arteritis and Wegener's granulomatosis, but not in oesteoarthritis. It is possible that the difference in von Willebrand factor antigen concentrations in two sub-groups of systemic necrotising arteritis (Wegener's granulomatosis and polyarteritis nodosum) may imply different disease processes. The large numbers involved have allowed us to confirm or question smaller studies of the role of this molecule in connective tissue disease.