title: Variations in glycosylation of von Willebrand factor with O-linked sialylated T antigen are associated with its plasma levels.
abstract: The glycosylation profile of von Willebrand factor (VWF) is known to strongly influence its plasma levels. VWF contains several carbohydrate structures, including O-linked glycans that primarily consist of sialylated T antigen (NeuAc(alpha2-3)Gal-(beta1-3)-[NeuAc(alpha2-6)]GalNAc). It is not yet known whether O-linked carbohydrates affect VWF levels. We developed an immunosorbent assay based on neuraminidase incubation allowing subsequent binding of peanut agglutinin (PNA) to desialylated O-linked T antigen on VWF. An inverse relation was found between PNA binding and VWF antigen levels in healthy individuals (n = 111; Pearson rank = -0.43; P < .001). A similar inverse association was observed in randomly selected plasma samples from our diagnostic laboratory: 252% +/- 125% for VWF levels less than 0.5 U/mL (n = 15); 131% +/- 36% for VWF levels between 0.5 and 1.5 U/mL (n = 32); and 92% +/- 40% for VWF levels more than 1.5 U/mL (n = 19). Reduced or increased PNA binding was also observed in patients with increased (liver cirrhosis) or reduced (von Willebrand disease [VWD] type 1) VWF antigen levels, respectively. VWD type 1 patients further displayed increased ratios of propeptide over mature VWF antigen levels (0.38 +/- 0.18 versus 0.17 +/- 0.03 for patients and controls, respectively; P < .001), which is indicative of reduced VWF survival in these patients. Of interest, a linear relation between PNA binding and propeptide/VWF ratio was observed (Spearman rank = 0.47), suggesting a potential association between O-linked glycosylation and VWF survival. Finally, we detected a marked decrease in PNA binding in post-DDAVP (1-deamino-8-D-arginine vasopressin) samples from various patients, indicating that the O-linked glycosylation profile of VWF stored in endothelial storage organelles may differ from circulating VWF.
authors.affiliation: Laboratory for Thrombosis and Haemostasis, Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Carina J M
authors.initials: CJ
authors.lastname: van Schooten
authors.forename: Cécile V
authors.initials: CV
authors.lastname: Denis
authors.forename: Ton
authors.initials: T
authors.lastname: Lisman
authors.forename: Jeroen C J
authors.initials: JC
authors.lastname: Eikenboom
authors.forename: Frank W
authors.initials: FW
authors.lastname: Leebeek
authors.forename: Jenny
authors.initials: J
authors.lastname: Goudemand
authors.forename: Edith
authors.initials: E
authors.lastname: Fressinaud
authors.forename: H Marijke
authors.initials: HM
authors.lastname: van den Berg
authors.forename: Philip G
authors.initials: PG
authors.lastname: de Groot
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lenting
mesh_terms: D000957:Antigens, Viral, Tumor / Q000097:blood* / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006031:Glycosylation; D006801:Humans; D008103:Liver Cirrhosis / Q000097:blood / Q000235:genetics; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D019887:Peanut Agglutinin / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D014841:von Willebrand Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000957:Antigens, Viral, Tumor; D019887:Peanut Agglutinin; D014841:von Willebrand Factor; D019158:N-Acetylneuraminic Acid