DEMONSTRATION AND MODE OF ACTION OF AN INHIBITOR FOR ACTIVATED HAGEMAN-FACTOR (FACTOR XIIA) OF INTRINSIC BLOOD-COAGULATION PATHWAY FROM SCHISTOSOMA-MANSONI

  • 1 January 1977
    • journal article
    • research article
    • Vol. 49  (4) , 619-633
Abstract
An anticoagulant activity from adult S. mansoni whole worm homogenate is described. The inhibitor appears specific for the contact activation step of the intrinsic pathway. Experiments with human and mouse plasmas defined the specificity of the inhibitor. It lengthened the partial thromboplastin time of normal plasma; and had no effect on the prothrombin time and Russell''s viper venom time of normal plasma. Preactivation of normal plasma by a contact activator such as Celite eliminated essentially all inhibitory activity. The inhibitor appeared heat stable and could be precipitated by centrifugation at > 27,000 g. The inhibitor had no effect on the activation of factor XII by Celite. The activation of factor XI by factor XIIa, was inhibited by the schistosomal inhibitor. The data are consistent with the view that S. mansoni adults possess an anticoagulant capable of specifically inhibiting the conversion of factor XI to factor XIa by factor XIIa.

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