Risky business: the interpretation, use, and abuse of antiphospholipid antibody tests in clinical practice.
Antiphospholipid antibodies (aPL) are best considered as risk factors. aPL are not diagnostic tests and considering them as such can be misleading and may direct attention away from the more important clinical issue of risk modification and management. When considering aPL as risk factors, quantitative aPL tests such enzyme-linked immunosorbent assay (ELISA) for anticardiolipin (aCL) and anti-beta(2)-glycoprotein I (anti-beta(2)GPI) antibodies, should be interpreted carefully. Risk for clinical manifestations appears to be associated with moderate to high levels of these autoantibodies. Lower levels may be statistically abnormal compared with a control population, but may not be associated with the risk of thrombosis or pregnancy loss. Lupus anticoagulants (LA) are generally thought to be more strongly associated with the risk of clinical manifestation of antiphospholipid syndrome (APS) than aCL and anti-beta(2)GPI antibodies. One reason for the stronger association may be related to patients' antibody titers. LA assays are not very analytically sensitive, i.e. a relatively high concentration of antibodies is required to prolong the clotting time in these tests. Thus, the presence of LA indicates a high titer of aPL and this, rather than the intrinsic functional characteristics of LA antibodies, may explain the high risk of clinical manifestations associated with LA.
Roubey
R A S
RA
Thurston Arthritis Research Center and Division of Rheumatology, Allergy, and Immunology, The University of North Carolina at Chapel Hill, NC 27599-7280, USA. roubey@med.unc.edu
D017153:Antibodies, Anticardiolipin / Q000276:immunology; D017152:Antibodies, Antiphospholipid / Q000276:immunology*; D016736:Antiphospholipid Syndrome / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000276:immunology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000209:etiology / Q000276:immunology; D012307:Risk Factors; D012308:Risk Management; D013927:Thrombosis / Q000209:etiology / Q000276:immunology; D053482:beta 2-Glycoprotein I / Q000276:immunology
D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D016682:Lupus Coagulation Inhibitor; D053482:beta 2-Glycoprotein I