Summary
Von Willebrand disease (vWD) results from quantitative (types 1 and 3) or qualitative
(type 2) deficiency of von Willebrand factor (vWF). This glycoprotein present in plasma
is involved in platelet adhesion at the site of vascular injury and serves as the
carrier of antihaemophilic A factor (FVIII). Whereas recent studies have identified
mutations in patients suffering from type 2 vWD, the integrity of the carbohydrate
moiety of vWF in these patients is still matter of debate. In order to analyse in
the plasma milieu the carbohydrate content of plasma vWF from various well-characterized
type 2 vWD patients, we developed a colorimetric assay in microtiter plate based on
the use of peroxidase- conjugated lectins specific for either α 2-6 sialic acid or
β 1-4 galactose. Removal of sialic acid from purified plasma vWF induced significant
changes in the reactivity of both lectins. The analysis of various normal plasmas
showed no influence of the blood groups and allowed us to compare various vWD patients.
The reactivity of lectins for plasma vWFs from two type 2A and six type 2B vWD patients
harbouring different mutations was not statistically different from that of a pool
of normal plasmas. We conclude that the α 2-6 sialic acid and β 1-4 galactose content
of plasma vWF is not altered in these patients affected with types 2A and 2B vWD.