PT 20210A
Turner's Syndrome





Research by La Jolla Pharmaceutical Company

(Extracted from latest release), for full report visit:  http://www.ljpc.com/product_research_thrombosis.html

Delay in Factor Va inactivation


Activated by thrombin, Factor Va (5a) plays a key role in blood coagulation. Factor Va acts as a co-factor to accelerate clot formation, giving rise to the nickname "accelerin." Factor Va has a strong procoagulant effect, prolonging the duration of clot formation. The inactivation of Factor Va is fundamental in controlling the clotting process. Factor Va helps accelerate clotting in the event of an injury, but Factor Va then needs to be rapidly inactivated by the body to prevent the clot from expanding. In normal individuals Factor Va generation and inactivation is regulated by activated protein C. It has been proposed that anticardiolipin antibodies impair the normal functioning of protein C.

Work in La Jolla Pharmaceutical Company laboratories has confirmed the observations of Galli, et al. (*1) that anticardiolipin antibodies from APS patients can delay the inactivation of Factor Va, leading to a prolongation of the clotting process. ACA can be isolated from patients, added to normal human serum and the levels of Factor Va monitored over time. While in the absence of ACA the normal serum levels of Factor Va rapidly return to baseline after clotting is initiated, the presence of ACA causes the Factor Va levels to remain elevated. At 20 minutes ACA from a typical patient cause the levels of Factor Va to be 50% higher than normal. We believe that these significantly higher levels of the procoagulant Factor Va may lead to an increased tendency to form blood clots. Removal of the ACA by our Tolerance Technology may correct the delay in Factor Va seen in APS patients and prevent the inappropriate blood clot formation seen with these patients.


  1.  Galli, M., Ruggeri, L., Barbui, T., Differential Effects of Anti-b2-Glycoprotein I and Antiprothrombin Antibodies on the Anticoagulant Activity of Activated Protein C . Blood, 1998, 91: No 6, 19992004.
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