Abstract
We investigated the effects of liposomes on the factor VIII activation by thrombin. The liposome consisting of phosphatidylserine and phosphatidylcholine (20:80, molar ratio) inhibited thrombin-activation of factor VIII in a dose-dependent manner with maximum 12% of the control, while PC liposome had no effect on the activation. Addition of PS/PC liposome apparently attenuated factor VIII activation rate during 20min time course. However, the thrombin cleavages of factor VIII heavy and light chains were comparable either in the presence of PS/PC liposome or PC liposome. Addition of PS/PC liposome after maximum activation of factor VIII led to rapid inactivation of factor VIII when compared to the addition of the control PC liposome. These results indicates that phosphatidylserine-containing liposome unstabilizes thrombin-activated factor VIII by a non-proteolytic mechanism.
