Verification of a rapid von Willebrand factor propeptide assay

Background: Von Willebrand disease (VWD) is the most common inherited bleeding disorder caused by a deficiency or defect in von Willebrand factor (VWF). Quantitative defects include, type 1 VWD and type 3 VWD. Type 1 VWD is either due to decreased synthesis and secretion, or increased clearance of VWF. It is essential to diagnose individuals with increased VWF clearance, as treatment of these patients with 1-deamino-8-D-arginine vasopressin is not effective. Currently, there is one commercial assay that measures von Willebrand factor propeptide (VWFpp) levels. This assay is time consuming to perform. With this research we developed and verified a rapid assay to determine VWFpp levels in patient plasma. Methods: The commercial VWF mouse anti-human VWF propeptide matched antibody pair (clones CLB-Pro 35 and CLB-Pro 14.3) was used in enzyme-linked immunosorbent assays of the commercial and the rapid method. While the CLB-Pro commercial assay uses two-hour incubations, our rapid assay uses 30 minute incubations. We compared our assay to the CLB-Pro commercial assay using twenty type 1 VWD patient plasma. Two samples, the World Health Organization (WHO) 6th International Standard (IS) for factor VIII (FVIII)/VWF and a type 1 VWD patient with increased clearance were also tested four times in duplicate for five consecutive days to determine the inter- and intra-assay precision. Results: Our rapid assay showed equal sensitivity to the CLB-Pro commercial assay by detecting 1.5625% VWFpp. The intra- and interassay CVs of our assay were acceptable according to the Food and Drug Administration guideline of 2018. Conclusion: This rapid enzyme-linked immunosorbent assay (ELISA) is as sensitive and precise as the CLB-Pro commercial assay. Therefore, it can be used to rapidly diagnose patients with increased VWF clearance.