Cellular interactions in hemostasis.
Coagulation reactions normally occur on cell membranes in vivo. Using a cell-based in vitro model system, we have shown that where a factor is located, not simply how much is activated, is critically important in determining its role in hemostasis. Factor Xa activated on a tissue factor (TF)-bearing cell is not equivalent to factor Xa activated on a platelet surface. Factor IX and factor VIII are required for hemostasis because they combine to generate factor Xa on the platelet surface. Factor X activation by factor VIIa/TF does not compensate for a lack of factor IX or VIII because the factor Xa activated by VIIa/TF is located on the wrong surface for efficient thrombin generation.
Hoffman
M
M
Duke University and Durham VA Medical Centers, The University of North Carolina, Chapel Hill, USA.
Monroe
D M
DM
Roberts
H R
HR
D001777:Blood Coagulation / Q000502:physiology; D002450:Cell Communication / Q000502:physiology*; D005164:Factor IX / Q000502:physiology; D005169:Factor VIII / Q000502:physiology; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D013925:Thromboplastin / Q000378:metabolism
D005169:Factor VIII; D005164:Factor IX; D013925:Thromboplastin