Antiphospholipid antibodies and thrombosis. A consequence, coincidence, or cause?

Antiphospholipid antibodies have been identified as a potential risk factor for both arterial and venous thromboembolic events. Whether these antibodies are causative or a consequence of a previous clinical event remains controversial. A variety of laboratory assays have been introduced to detect the two primary members of the antiphospholipid antibody family: (1) lupus anticoagulants and (2) anticardiolipin antibodies. There is considerable variability in the laboratory tests that have been utilized. A number of potential pathogenic mechanisms have been proposed for antiphospholipid antibodies. These mechanisms involve the interaction of antiphospholipid antibodies with endothelial cells, platelets, and various plasma regulatory proteins. Although venous thromboembolic events are more common, recent evidence suggests a high frequency of arterial events. The cerebral circulation is most commonly involved, followed by involvement of the coronary arteries. An interesting subset of young patients have peripheral vascular disease that often is relatively refractory to surgical treatment with a high incidence of graft occlusion.