Abstract
Platelet-associated factor XIII provides a means by which to promote clot stabilization
and platelet interaction with proteins of the coagulation and fibrinolytic pathways.
In addition to its intracellular role within the platelet cytoplasm, activated factor
XIII will bind to the surface of activated platelets. These platelets then participate
in cell-cell or cell-clot interactions, thereby increasing the local concentration
of factor XIIIa. The platelet-associated factor XIIIa may increase the amount of crosslinking
in a fibrin clot, thereby contributing to the aging of the clot and the reduction
in the degree of platelet binding. Clot resistance to fibrinolysis is enhanced by
platelet factor XIIIa-mediated crosslinking of α2-antiplasmin to fibrin. The binding of factor XIIIa to the platelet surface requires
the activation of the platelet fibrinogen receptor, glycoprotein IIb-IIIa. Thus, platelet-associated
factor XIIIa may be used as a marker of in vivo platelet activation. Since half of
the factor XIII present in blood is provided by the platelets, it is not surprising
that this form of factor XIII plays an important role in hemostasis.
Key words:
Factor XIII - platelet activation - clot stabilization - glycoprotein IIb-IIIa - fibrin
