What is the pathogenetic role of antiphospholipid antibodies?

The association between antiphospholipid antibodies (aPL) and arterial or venous thrombosis, fetal loss and thrombocytopenia defines the so-called 'antiphospholipid syndrome' (APS). Despite serial studies in recent years, a clear pathogenetic mechanism(s) has not yet been demonstrated. Several authors have investigated the interaction between aPL and the membranes of blood cells (endothelial cells and platelets) involved in coagulation. aPL is also thought to affect the balance between the procoagulant and anticoagulant states by interacting with plasma or tissue cofactors. Finally, the strong association between aPL and experimental animal models of fetal loss supports a direct pathogenetic role for aPL in inducing a poor pregnancy outcome in APS women.