Mechanisms of Action of Antiphospholipid Antibodies in the Antiphospholipid Syndrome

Antiphospholipid antibody syndrome (APS) is characterized by autoantibodies against negatively charged phospholipids in the serum, and clinically by multiple thromboses, thrombocytopenia, and recurrent fetal loss. The mechanism(s) by which the antibodies cause the clinical picture are not clear. We review the possible mechanisms of action of antiphospholipid (aPL) antibodies. Apparently, aPL antibodies act by interfering with coagulation, involving both endothelial cells, platelets, and humoral components, and affect pregnancy outcome by interfering with embryo implantation and fetal development.