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Defective ristocetin-induced platelet aggregation in von Willebrand's disease and its correction by factor VIII

H J Weiss, J Rogers, H Brand

    The Journal of Clinical Investigation
    |November 1, 1973
    PubMed

    Insights

    Patients with von Willebrand's disease show impaired platelet aggregation due to a deficiency in a plasma factor. This factor, linked to Factor VIII, is crucial for normal platelet function and bleeding time.

    Area of Science:

    • Hematology
    • Platelet Physiology
    • Coagulation Disorders

    Background:

    • Ristocetin induces platelet aggregation through a mechanism minimally involving the release reaction.
    • Von Willebrand's disease (vWD) is characterized by bleeding abnormalities.
    • Antihemophilic factor (AHF, Factor VIII) is crucial for blood coagulation.

    Purpose of the Study:

    • To investigate the role of a plasma factor in ristocetin-induced platelet aggregation in patients with von Willebrand's disease.
    • To determine the relationship between this factor, Factor VIII, and platelet function.
    • To characterize the corrective properties of plasma and cryoprecipitate fractions.

    Main Methods:

    • Assessing ristocetin-induced platelet aggregation in normal individuals and patients with vWD at varying concentrations.
    • Correlating aggregation defects with bleeding times and antihemophilic factor (AHF, Factor VIII) procoagulant activity levels.
    • Evaluating the in vitro corrective effects of normal plasma, normal cryoprecipitate fractions, and fractions from vWD and hemophilia patients.
    • Testing the inhibitory effects of antibodies against human Factor VIII.

    Main Results:

    • Ristocetin-induced platelet aggregation was significantly reduced or absent in patients with von Willebrand's disease.
    • The severity of the aggregation defect correlated with abnormal bleeding times and reduced AHF (Factor VIII) procoagulant activity.
    • Normal plasma and cryoprecipitate fractions containing AHF (Factor VIII) corrected the aggregation defect.
    • Fractions from vWD patients lacking AHF (Factor VIII) showed no correction, while those from hemophilia patients were effective.
    • Antibodies to human Factor VIII inhibited the corrective activity.

    Conclusions:

    • Patients with von Willebrand's disease possess a deficiency in a plasma factor essential for normal platelet aggregation.
    • This deficient factor is associated with, but distinct from, the procoagulant activity of AHF (Factor VIII).
    • The findings support the existence of a specific von Willebrand factor responsible for platelet adhesion and aggregation.

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