Platelet von Willebrand factor assay: results using two methods for platelet lysis

Area of Science:

• Hematology
• Biochemistry
• Molecular Biology

Background:

• Platelets play a crucial role in hemostasis and thrombosis.
• Von Willebrand factor (vWF) is a key protein involved in platelet adhesion and aggregation.
• Accurate measurement of platelet vWF is essential for diagnosing and managing bleeding disorders.

Purpose of the Study:

• To compare the efficacy of Triton X-100 and glycerol lysis methods for measuring platelet vWF concentrations.
• To evaluate the impact of storage duration on vWF antigen (vWF:Ag) and ristocetin cofactor activity (Ricof).
• To assess the integrity of vWF multimeric forms after different lysis and storage conditions.

Main Methods:

• Platelet lysates were prepared using two methods: Triton X-100 and glycerol.
• Platelet vWF:Ag and Ricof concentrations were measured.
• vWF multimeric patterns were analyzed.
• Samples were stored at -80°C for two months.

Main Results:

• Platelet vWF:Ag levels were similar between Triton X-100 and glycerol lysis methods.
• Ricof activity was significantly higher in platelet lysates prepared with Triton X-100 compared to glycerol.
• Both lysis methods showed a decrease in vWF:Ag and Ricof after two months of storage.
• Supranormal vWF multimeric forms were observed with both methods, with no changes during storage.

Conclusions:

• Triton X-100 is recommended for platelet lysis when measuring platelet vWF concentration, particularly for Ricof activity.
• To ensure accurate Ricof measurements, platelet lysates should be assayed within two weeks of preparation.
• Storage at -80°C for extended periods can lead to a decay in vWF Ricof activity, irrespective of the lysis method used.