Recent advances in the diagnosis of antiphospholipid syndrome.

Antiphospholipid antibodies are autoantibodies directed against anionic phospholipids or protein-phospholipid complexes measured in solid-phase immunoassays such as anticardiolipin (aCL) antibody or detected in phospholipid-dependent clotting tests as lupus anticoagulant (LA). The term "antiphospholipid syndrome (APS)" was first coined to denote the clinical association between antiphospholipid antibodies and a syndrome of episodes of thrombosis in arteries and/or veins, pregnancy loss, and thrombocytopenia. The diagnosis of APS is based on the finding of "moderate-to-high" aCL antibody titer and/or an LA test with any one of the characteristic clinical features presented. Recently, the diagnostic criteria of APS was revised and several newer assays that use phosphatidylserine, a mixture of negatively charged phospholipids or beta2-glycoprotein 1 (beta2-GP1) have been proposed for more specific measurements of antibodies present in APS. In this section, recent progress in the laboratory diagnosis of antiphopholipid syndrome will be discussed.