Measurement of von Willebrand factor activity: relative effects of ABO blood type and race

J Thromb Haemost. 2003 Oct;1(10):2191-7. doi: 10.1046/j.1538-7836.2003.00367.x.


Tests based on three different principles are reported to measure the activity of von Willebrand factor (VWF): ristocetin cofactor (VWF:RCo), collagen binding (VWF:CB), and the so-called "activity ELISA" (VWF:MoAb). We measured these and other diagnostic parameters in a population of 123 randomly selected female study controls, age 18-45 years. Type O subjects had significantly lower levels than non-O subjects in each test. Race differences were seen in all tests except VWF:RCo, with Caucasians having significantly lower levels than African-Americans. ABO differences accounted for 19% of the total variance in VWF:Ag (P < 0.0001) and race for 7% (P < 0.0001), for a total of 26%. Both effects were mediated through VWF:Ag and were independent. VWF:Ag level was the primary determinant of VWF function, accounting for approximately 60% of the variance in VWF:RCo and VWF:CB and 54% of the variance in factor VIII. The ratio VWF:RCo/VWF:Ag differed significantly by race within blood group. The median ratios were 0.97 for type O Caucasians vs. 0.79 for type O African-Americans and 0.94 for non-O Caucasians vs. 0.76 for non-O African-Americans. The ratio VWF:CB/VWF:Ag did not vary. This suggests racial differences in the interaction of VWF with GP1b but not with subendothelium. Alternatively, VWF:RCo may be regulated to maintain a relatively constant plasma level in the presence of excessive VWF:Ag. This heterogeneity within the normal population is partially responsible for the difficulty in defining diagnostic limits for von Willebrand disease.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ABO Blood-Group System*
  • Adolescent
  • Adult
  • Blacks
  • Blood Grouping and Crossmatching
  • Blood Proteins / metabolism
  • Collagen / metabolism*
  • Endothelium, Vascular / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Glycoproteins / metabolism
  • Humans
  • Immunoglobulins / metabolism
  • Middle Aged
  • Normal Distribution
  • Racial Groups
  • Ristocetin / metabolism*
  • Whites
  • von Willebrand Diseases / blood
  • von Willebrand Factor / metabolism*


  • A1BG protein, human
  • ABO Blood-Group System
  • Blood Proteins
  • Glycoproteins
  • Immunoglobulins
  • von Willebrand Factor
  • Ristocetin
  • Collagen