von Willebrand factor antigen compared with other factors in vasculitic syndromes.

In order to analyse their role as a specific marker of vascular damage and their value in monitoring disease activity the plasma concentrations of von Willebrand factor antigen (vWFAg) and the ristocetin cofactor (RiCoF) activities were determined in 43 children with vasculitis and 20 controls. These patients were sub-divided into three groups according to diagnosis: Henoch-Schönlein purpura (n = 18), polyarteritis nodosa (n = 16), and systemic lupus erythematosus (n = 9). High concentrations of vWFAg and activities of RiCoF were found in all the patient groups. vWFAg and RiCoF returned to normal as the patients became symptom free and remained above normal in those with continuing symptoms. The amount of vWFAg did not correlate with the acute phase reactants. vWFAg acted as a specific marker of vascular damage and was useful for the monitoring of disease activity both in small vessel vasculitis and systemic necrotising arteritis.