Platelet Adhesion to Multimeric and Dimeric von Willebrand Factor and to Collagen Type III Preincubated With von Willebrand Factor

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Abstract
As part of a systematic study of platelet interaction with adhesive proteins under flow conditions, we studied platelet adhesion to multimeric and dimeric von Willebrand factor (vWF) coated to glass. vWF-dependent adhesion to collagen type III was studied for comparison. Adhesion to glass-coated vWF and vWF-mediated adhesion to collagen type III were in many respects similar. Both showed no decrease at increasing shear rates and a decline to 50% of maximum with a low-molecular-weight multimeric fraction. Adhesion to glass-coated vWF was partially inhibited by heparin and completely inhibited by prostaglandin I 2 and anti–glycoprotein (GP) Ib and anti–GPIIb-IIIa antibodies. vWF-dependent adhesion to collagen was not inhibited by heparin, was partially inhibited by anti–GPIIb-IIIa, and was completely inhibited by prostaglandin I 2 and anti-GPIb. Recombinant dimeric vWF was made by deletion of the propeptide and expression in Chinese hamster ovary cells. Adhesion was 50% of that with plasma vWF, and larger concentrations of dimeric vWF were required. Adhesion to dimeric vWF was optimal at 1500 s −1 , with a gradual decrease at higher shear rates. We conclude that adhesion to collagen type III is strongly but not completely determined by the adhesive properties of vWF.