QUANTITATIVE-ANALYSIS OF VON-WILLEBRAND-FACTOR AND ITS PROPEPTIDE IN PLASMA IN ACQUIRED VON-WILLEBRAND SYNDROME

Measurement of the von Willebrand factor (vWF) propeptide, also known as von Willebrand antigen II, has been suggested to be helpful in the discrimination of congenital von Willebrand disease type I from type 2 and in assessing the extent of activation of the endothelium. We perf ormed a quantitative analysis of mature VWF and its propeptide in plas ma in 8 patients with acquired von Willebrand syndrome (AvWS) and in 2 0 normal individuals. Mature vWF levels were significantly lower in Av WS as compared with normal individuals (13.4 +/- 3.5 vs 35.6 +/- 3.3 n M, p < 0.001). In contrast, propeptide levels were significantly highe r in AvWS (11.4 +/- 1.1 vs 4.7 +/- 0.2 nM, p < 0.001), probably reflec ting a compensatory increase in vWF synthesis or increased perturbatio n of the endothelium in AvWS. After treatment with DDAVP, propeptide a nd mature vWF levels rose 5-fold in AvWS, whereas propeptide levels we re not altered by the infusion of a VWF concentrate or treatment with high dose intravenous immunoglobulins, indicating that plasma propepti de levels are a reliable reflection of VWF synthesis. Measurement of p ropeptide levels may provide additional:information in AvWS as to whet her decreased levels of mature vWF ii the circulation are due to a dec rease in synthesis or due to ar. accelerated removal of vWF from the c irculation.