Humoral autoimmunity against endothelium : theory or reality?

Despite the discovery of anti-endothelial cell antibodies (AECA) in a heterogeneous group of disorders characterized by endothelial damage, their pathogenic role is still debated. Experimental in vitro models indicate that they can either damage endothelial cells or trigger cell signaling by reacting with as yet undefined surface molecules. However, clinical studies suggest that, in addition to AECA, other pathogenic mechanisms are involved in the vasculitic process. Recently, antibodies specific for beta 2 glycoprotein I, the phospholipid-binding protein targeted by anti-phospholipid antibodies, have been shown to display anti-endothelial activity. These autoantibodies recognize beta 2 glycoprotein I adhered to the endothelium and induce a cell perturbation that might underlie the thrombophilic state of the anti-phospholipid syndrome.