Thromb Haemost 1996; 75(01): 049-055
DOI: 10.1055/s-0038-1650220
Original Article
Schattauer GmbH Stuttgart

β2-Glycoprotein I Modulates the Anticoagulant Activity of Activated Protein C on the Phospholipid Surface

Tatsuyuki Mori
The Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie, Japan
,
Hiroyuki Takeya
The Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie, Japan
,
Junji Nishioka
The Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie, Japan
,
Esteban C Gabazza
The Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie, Japan
,
Koji Suzuki
The Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie, Japan
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Publikationsverlauf

Received 28. April 1995

Accepted after resubmission 19. September 1995

Publikationsdatum:
10. Juli 2018 (online)

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Summary

The objective of this study was to determine whether (β2-glycoprotein I (β2GPI) has procoagulant activity by inhibiting the anticoagulant activity of activated protein C (APC). β2GPI inhibited significantly the APC-catalyzed inactivation of factor Va in an assay using factor V-deficient plasma and physiological levels of protein S and factor Va. This inhibitory effect was diminished by the addition of increasing concentrations of phospholipids, suggesting that β2GPI competitively inhibits the binding of APC to the phospholipid surface. β2GPI inhibited weakly factor Va- and phospholipid-dependent prothrombinase activity at concentrations similar to those to inhibit APC activity. The depletion of β2GPI from plasma led to only a slight shortening of the diluted Russell’s viper venom-dependent clotting time, but to a strong and significant potentiation of the anticoagulant activity of APC. These results suggest that under certain physiological conditions β2GPI has procoagulant property by inhibiting the phospholipid-dependent APC anticoagulant activity.