Mechanisms of activity of lupus anticoagulants

Lupus anticoagulants comprise a heterogenous group of circulating immunoglobulins that are associated with an increased risk of thrombosis. It was believed earlier that these antibodies were directed against anionic phospholipids. Recent findings, however, establish that the autoantibodies in lupus anticoagulants are not directed against "native" anionic phospholipids but rather to modified phospholipids, lipid-protein adducts, and certain phospholipid binding proteins. Despite a marked increase in the number of citations in recent years on laboratory and clinical manifestations of lupus anticoagulants, the pathogenetic mechanisms involved remain unknown. This review focuses on antigen specificities of autoantibodies in lupus anticoagulants and the mechanisms by which these antibodies contribute to an increased thrombotic risk in patients with lupus anticoagulant.