Abstract
Background:The ultra-large von Willebrand factor (vWF) multimers are very active and must be degraded by ADAMTS13 for optimal activity. A severe functional deficiency of ADAMTS13 has been associated with thrombotic thrombocytopenic purpura. The correct interpretation of patient vWF and ADAMTS13 plasma levels requires an understanding of the biological variation associated with these analytes. In the present paper, we aimed to determine the biological variation of ADAMTS13 and vWF in human adults.Materials and methods:Blood samples were collected weekly from 19 healthy subjects for 5 consecutive weeks. vWF activity and antigenicity were determined using aggregometric and immunoturbidimetric methods. ADAMTS13 antigenicity and activity were determined by ELISA.Results:The within-subject biological variations for vWF activity and antigenicity were 8.06% and 14.37%, respectively, while the between-subject biological variations were 18.5% and 22.59%, respectively. The index of individuality for vWF activity was 0.44, while vWF antigenicity was 0.64. Similarly, ADAMTS13 activity and antigenicity within-subject biological variations were 12.73% and 9.75%, respectively, while between-subject biological variations were 9.63% and 6.28%, respectively. The ADAMTS13 indexes of individuality were 1.32 and 1.55, respectively.Conclusion:We report high biological variation and individuality in vWF antigenicity and activity levels. However, ADAMTS13 antigenicity and activity displayed high biological variation, but low individuality. Thus, population-based reference intervals may be useful for monitoring ADAMTS13 antigenicity and activity, but not for vWF, which displays high individuality. These findings should be considered when determining the reference interval and other clinical variables associated with ADAMTS13 and vWF levels.
Highlights
Von Willebrand factor is a multimeric glycoprotein that plays a major role in the primary hemostatic process
Population-based reference intervals may be useful for monitoring ADAMTS13 antigenicity and activity, but not for von Willebrand factor (vWF), which displays high individuality
These findings should be considered when determining the reference interval and other clinical variables associated with ADAMTS13 and vWF levels
Summary
Von Willebrand factor (vWF) is a multimeric glycoprotein that plays a major role in the primary hemostatic process. It is synthesized in endothelial cells and megakaryocytes, and secreted as ultralarge vWF (ULvWF). VWF multimers are formed within the endoplasmic reticulum and secreted into the plasma primarily by endothelial cells where additional processing occurs [1]. In the case of ADAMTS13 deficiency, vWF forms large multimers in the plasma, which spontaneously bind platelets and induce aggregation [4,5]. The activity of ADAMTS13 in TTP patients is severally deficient, being less than 5% of normal plasma activity [6,7]. We aimed to determine the biological variation of ADAMTS13 and vWF in human adults
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