BETA(2)-GLYCOPROTEIN-I AND ANTICARDIOLIPIN ANTIBODY-BINDING TO RESTING AND ACTIVATED CULTURED HUMAN ENDOTHELIAL-CELLS

Objective. To examine beta(2)-glycoprotein I (beta(2)-GPI) binding and its ability to augment Ige anticardiolipin (aCL) antibody binding to resting and cytokine activated endothelial cells in vitro. To evaluate the ability of Ige aCL antibody positive sera to induce endothelial c ell activation in vitro. Methods, IgG with aCL activity was isolated b y affinity purification from 6 patients with systemic lupus erythemato sus (SLE) and 3 patients with primary antiphospholipid antibody syndro me (APS). Human umbilical vein endothelial cells (HUVEC) were cultured in serum-free conditions and examined in a resting state or after act ivation with tumor necrosis factor alpha (TNF-alpha). HUVEC were expos ed to beta(2)-GPI alone, IgG alone or Ige plus beta(2)-GPI, Finally, w e examined the ability of sera from the same patients with SLE and pri mary APS to activate HUVEC in culture. Results, Neither beta(2)-GPI, I gG aCL, nor IgG aCL plus beta(2)-GPI bound to resting or cytokine acti vated endothelial cells. In addition, sera from the same patients did not induce in vitro activation of endothelial cells as assessed by enh anced surface expression of intercellular adhesion molecule, vascular cell adhesion molecule, and E-selectin. Conclusion. Results suggest th at beta(2)-GPI deposition on either resting or activated endothelial c ells and modulation of its proposed in vivo anticoagulant activity thr ough subsequent aCL antibody binding does not account for the thrombot ic manifestations of APS.