title: von Willebrand factor and its propeptide: the influence of secretion and clearance on protein levels and the risk of venous thrombosis.
abstract: OBJECTIVE
  Elevated levels of factor (F)VIII are associated with an increased risk of thrombosis. FVIII levels are determined mainly by von Willebrand factor (VWF). We have investigated the contribution of secretion and clearance rates to the elevated VWF antigen (VWF:Ag) and to the risk of thrombosis. VWF is secreted in equimolar amounts with its propeptide, which has a shorter half-life. VWF propeptide can be used as a measure of VWF secretion and allows estimation of the VWF half-life.
  
  
  RESULTS
  We have measured VWF propeptide, VWF:Ag, FVIII:Ag and FVIII activity (FVIII:C) in the Leiden Thrombophilia Study. In controls, high VWF propeptide was associated with high VWF:Ag, FVIII:Ag and FVIII:C. In contrast to mature VWF:Ag, VWF propeptide was not influenced by blood groups. Using an ELISA-based assay we have shown that VWF propeptide lacks ABO antigens. Levels were higher in men and increased with age. A long VWF half-life was also associated with high VWF:Ag, FVIII:Ag and FVIII:C. The VWF half-life was influenced by blood group (10 h in O vs. 12 h in non-O individuals), but not by sex, and only slightly by age. VWF propeptide was higher in thrombosis patients than in controls. The VWF half-life was similar in patients and controls (11.4 and 11.1 h, respectively).
  
  
  CONCLUSIONS
  Both secretion and clearance rates are important determinants of VWF and FVIII levels. However, mainly high VWF and FVIII levels caused by increased secretion seem to be associated with thrombosis. ABO blood group influences the clearance rates of VWF rather than VWF secretion rates.
authors.affiliation: Hematology, Hemostasis and Thrombosis Research Center, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: A Y
authors.initials: AY
authors.lastname: Nossent
authors.forename: V
authors.initials: V
authors.lastname: VAN Marion
authors.forename: N H
authors.initials: NH
authors.lastname: VAN Tilburg
authors.forename: F R
authors.initials: FR
authors.lastname: Rosendaal
authors.forename: R M
authors.initials: RM
authors.lastname: Bertina
authors.forename: J A
authors.initials: JA
authors.lastname: VAN Mourik
authors.forename: H C J
authors.initials: HC
authors.lastname: Eikenboom
mesh_terms: D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D000368:Aged; D000941:Antigens / Q000097:blood / Q000378:metabolism; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005169:Factor VIII / Q000378:metabolism; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D011498:Protein Precursors / Q000097:blood / Q000378:metabolism*; D012016:Reference Values; D018570:Risk Assessment; D019851:Thrombophilia / Q000097:blood / Q000150:complications / Q000276:immunology / Q000378:metabolism*; D020246:Venous Thrombosis / Q000097:blood / Q000209:etiology* / Q000276:immunology / Q000378:metabolism*; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D000017:ABO Blood-Group System; D000941:Antigens; D015415:Biomarkers; D011498:Protein Precursors; C029417:Von Willebrand antigen; D014841:von Willebrand Factor; C067003:von Willebrand factor propolypeptide; D005169:Factor VIII