Contributions of human platelets to the proteolytic activation of blood coagulation factors XII and XI

Authors:
  • PWPn Walsh
    Pn Walsh
  • JGJh Griffin
    Jh Griffin
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Abstract
Previous studies have suggested that human platelets can promote the activation of factor XI by two different mechanisms, one requiring factor XII and ADP-treated platelets and the other requiring collagen-treated platelets in the apparent absence of factor XII. To investigate these hypotheses. isolated platelets were tested for their capacity to promote the activation and cleavage of purified factors XII and Xl in various mixtures of purified factor XII. kallikrein. high molecular weight (HMW) kininogen. and factor XI. The activation of factor XII or factor XI was tested in clotting assays using plasmas deficient in factor XII. Xl. IX.