The Influence of β2-Glycoprotein I on Tissue Factor Activity

Masahiro Ieko; Taro Yasukouchi; Ken-Ichi Sawada; Takao Koike

doi:10.1055/s-2007-995844

Seminars in Thrombosis and Hemostasis, Table of Contents

Semin Thromb Hemost 1998; 24(3): 211-215
DOI: 10.1055/s-2007-995844

The Influence of β2-Glycoprotein I on Tissue Factor Activity

Masahiro Ieko^* , Taro Yasukouchi^† , Ken-Ichi Sawada^‡ , Takao Koike^‡

From the *Department of Internal Medicine,
†Research Institute of Medical Science, Health Science University of Hokkaido, and
‡Department of Internal Medicine II, Hokkaido University School of Medicine, Japan

Abstract

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Abstract

The β2-glycoprotein I (β2-GPI) is known for its procoagulant as well as anticoagulant properties. The influence of β2-GPI on tissue factor (TF) activity was investigated by chromogenic assays for both factor Xa generation and factor VIIa activity. When 1.36 mg/mL β2-GPI was added to phospholipids prior to the addition of TF and factor VIIa, the TF activity was moderately inhibited by β2-GPI in a concentration-dependent manner. Inhibition of TF activity by β2-GPI required incubation for at least 20 min. When β2-GPI was added to the mixture of phospholipids and TF followed by the addition of factor VIIa, the TF activity was little affected by the addition of β2-GPI. The TF activity was inhibited when β2-GPI was added after forming a complex with TF and factor VIIa. The results suggest that β2-GPI inhibits both the reconstitution of TF with phospholipids and factor Xa generation by the TF factor-VIIa complex but does not affect the formation of a TF factor-VIIa complex.

Keywords:

Tissue factor - β2-glycoprotein I - chromogenic assay

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