Do some antiphospholipid antibodies target endothelial cells?
Anti-endothelial cell activity is partly due to antiphospholipid antibodies (aPLA) because: a) the two types of antibodies are present in patients with connective tissue diseases and cardiolipin-binding monoclonal antibodies recognize endothelial cells (EC); b) anionic phospholipids are detectable on the outer face of the EC membrane lipid bilayer and an anti-beta 2-glycoprotein I (beta 2-GPI) monoclonal antibody binds to EC; c) the binding of aPLA to EC and the functional affinity of this binding are dependent on the presence of beta 2-GPI; d) anti-EC antibodies trigger the expression of anionic phospholipids on the outer leaflet of the EC membrane.