Some recent developments with lupus anticoagulants.
Lupus anticoagulants (LA) have been defined as phospholipid-interfering antibodies. Testing for them has become a frequently requested procedure in coagulation laboratories and new methods have recently become available. Activated partial thromboplastin time (aPTT) reagents with reduced levels or different types of phospholipid provide high sensitivity. Correction procedures resistant to heparin and based on aPTT and dilute Russell's viper venom time (DRVVT) tests with added hexagonal phase phospholipids have improved the specificity of testing. Simplified tests based on venom activators of factor X and prothrombin improve the reliability of LA testing and may facilitate the further categorization of circulating anticoagulants. Recent studies on the mechanism of LA derived from various patients have confirmed their heterogeneity, principally in the protein cofactors involved in their interactions with phospholipids. Perhaps one-third of LA require beta 2-glycoprotein 1 to exert an anticoagulant effect. The remainder may require human prothrombin as suggested from studies with reconstituted clotting factor systems.
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Haemostasis Reference Laboratory, Westmead Hospital, Sydney, NSW, Australia.
D017152:Antibodies, Antiphospholipid / Q000097:blood; D001053:Apolipoproteins / Q000032:analysis; D001777:Blood Coagulation / Q000187:drug effects*; D001780:Blood Coagulation Tests; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D053482:beta 2-Glycoprotein I
D017152:Antibodies, Antiphospholipid; D001053:Apolipoproteins; D006023:Glycoproteins; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I