Endothelial cells as target for antiphospholipid antibodies. Human polyclonal and monoclonal anti-beta 2-glycoprotein I antibodies react in vitro with endothelial cells through adherent beta 2-glycoprotein I and induce endothelial activation

Arthritis Rheum. 1997 Mar;40(3):551-61. doi: 10.1002/art.1780400322.


Objective: To investigate the ability of human anti-beta 2-glycoprotein I (anti-beta 2 GPI) antibodies to recognize the cofactor adherent on endothelial cells (EC) and to modulate endothelial functions.

Methods: Six human affinity-purified polyclonal anti-beta 2 GPI IgG and 2 IgM monoclonal antibodies (MAb) were obtained from patients with the antiphospholipid syndrome. The antibodies were tested for their ability to 1) bind to endothelial monolayers through the adherent beta 2 GPI and 2) modulate endothelial adhesion molecule expression and interleukin-6 (IL-6) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) secretion.

Results: The affinity-purified IgG and the MAb with anti-beta 2 GPI activity, but not the respective controls, displayed EC binding, which declined on cells incubated in serum-free medium and was restored in a dose-dependent manner by exogenous human beta 2 GPI. After EC binding, both polyclonal and monoclonal antibodies up-regulated adhesion molecule expression. Anti-beta 2 GPI MAb also significantly increased IL-6 and 6-keto-PGF1 alpha secretion.

Conclusion: These findings support the hypothesis that anti-beta 2 GPI antibodies bind and activate EC through the adherent cofactor beta 2 GPI, likely leading to a procoagulant state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Ketoprostaglandin F1 alpha / biosynthesis
  • Adult
  • Antibodies, Antiphospholipid / physiology*
  • Antibodies, Monoclonal / metabolism
  • Antiphospholipid Syndrome / blood
  • Apolipoproteins / blood
  • Apolipoproteins / immunology
  • Cell Adhesion / immunology
  • Cell Adhesion Molecules / biosynthesis
  • Cells, Cultured
  • Chromatography, Affinity
  • Endothelium, Vascular / cytology*
  • Endothelium, Vascular / immunology
  • Endothelium, Vascular / metabolism
  • Epitopes
  • Female
  • Glycoproteins / blood
  • Glycoproteins / immunology
  • Humans
  • Immunoglobulin G / isolation & purification
  • Interleukin-6 / biosynthesis
  • Male
  • Protein Binding
  • Umbilical Veins / cytology
  • beta 2-Glycoprotein I


  • Antibodies, Antiphospholipid
  • Antibodies, Monoclonal
  • Apolipoproteins
  • Cell Adhesion Molecules
  • Epitopes
  • Glycoproteins
  • Immunoglobulin G
  • Interleukin-6
  • beta 2-Glycoprotein I
  • 6-Ketoprostaglandin F1 alpha