[Antiphospholipid antibodies--antiphospholipid syndrome. Cause or consequence of thrombosis]

Antiphospholipid antibodies (APA) are heterogeneous immunoglobulines of G, M or A classes with specificity directed towards anionic phospholipids. The APA are associated with a wide variety of diseases. They have been found to represent risk factor for development of arterial and/or veinous thrombosis. The APA would perturbed the biological activities of anionic phospholipid surface in a manner that could decrease the natural anti-coagulant pathway in order to lead to thrombosis. In the latter hypothesis APA would appear as a secondary response to the exposure of phospholipid "self antigens" by activated or damaged blood vascular cells by known stimuli able to induce thrombosis. In these cases APA would therefore constitute a marker of risk of thrombosis. The question which remains to be solved is if APA possess their own pathogenic potential or if they appear as the result of an up-stream pathological event known to be favourable to the development of thrombosis or if both mechanism are involved.