beta 2 glycoprotein-I inhibits factor XII activation on triglyceride rich lipoproteins: the effect of antibodies from plasma of patients with antiphospholipid syndrome

Thromb Haemost. 1996 Aug;76(2):220-5.


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, beta 2 glycoprotein-I (beta 2 GPI), for binding to phospholipids, and recently beta 2 GPI has been identified as the antigenic target for some aPAs. beta 2 GPI possesses in vitro anticoagulant properties and modulation of beta 2 GPI function may therefore result in altered haemostatic regulation. In the present study, the influence of plasma derived aPAs and beta 2 GPI 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 beta 2 GPI 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 beta 2 GPI 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 beta 2 GPI function may contribute to the pathogenic mechanism for thrombosis in some patients with aPAs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies / blood*
  • Antibodies, Anticardiolipin / blood
  • Antiphospholipid Syndrome / blood*
  • Case-Control Studies
  • Factor XIIa / biosynthesis*
  • Female
  • Glycoproteins / physiology*
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin G / physiology
  • Lipoproteins, VLDL / blood
  • Lipoproteins, VLDL / chemistry*
  • Male
  • Middle Aged
  • Triglycerides / blood*
  • beta 2-Glycoprotein I


  • Antibodies
  • Antibodies, Anticardiolipin
  • Glycoproteins
  • Immunoglobulin G
  • Lipoproteins, VLDL
  • Triglycerides
  • beta 2-Glycoprotein I
  • Factor XIIa