Thromb Haemost 1996; 76(02): 220-225
DOI: 10.1055/s-0038-1650558
Original Article
Schattauer GmbH Stuttgart

β2 Glycoprotein-I Inhibits Factor XII Activation on Triglyceride Rich Lipoproteins: The Effect of Antibodies from Plasma of Patients with Antiphospholipid Syndrome

T McNally
The Department of Haematology, University College London Medical School London, UK
,
I J Mackie
The Department of Haematology, University College London Medical School London, UK
,
D A Isenberg
1   The Department of Rheumatology, University College London Medical School London, UK
,
S J Machin
The Department of Haematology, University College London Medical School London, UK
› Author Affiliations
Further Information

Publication History

Received 03 October 1995

Accepted after resubmission 12 April 1996

Publication Date:
10 July 2018 (online)

Summary

It is now well recognised that antiphospholipid antibodies are associated with thrombosis and recurrent fetal loss. Some antiphospholipid antibodies (aPAs) have been shown to require a cofactor, β2 glyco-protein-I (β2GPI), for binding to phospholipids, and recently β2GPI has been identified as the antigenic target for some aPAs. β2GPI possesses in vitro anticoagulant properties and modulation of β2GPI function may therefore result in altered haemostatic regulation. In the present study, the influence of plasma derived aPAs and β2GPI on factor XII activation on the surface of very low density lipoprotein (VLDL) was investigated. Factor XIIa generation was dependent on lipoprotein lipase treatment of VLDL and β2GPI inhibited the factor XIIa generation in a concentration dependent manner. No consistent effects on factor XIIa generation were demonstrated with the IgG fractions from patients with aPAs. Inhibition of the β2GPI activity was demonstrated by some antibodies, and study with cardiolipin affinity purified antibody indicated that antibody concentration is critical. These results suggest that perturbation of β2GPI function may contribute to the pathogenic mechanism for thrombosis in some patients with aPAs. .