Phospholipid-dependent anti-beta 2-glycoprotein I (beta 2-GPI) antibodies and antiphospholipid syndrome

A portion of anticardiolipin antibodies is defined as phospholipid-dependent anti-beta 2-glycoprotein I (beta 2-GPI) antibodies and recognizes the conformationally altered beta 2 GPI which interacts with anionic phospholipids. We studied the clinical significance of IgG phospholipid-dependent anti-beta 2-GPI antibodies in patients with antiphospholipid syndrome (APS). The subjects consisted of 60 APS patients. IgG phospholipid-dependent anti-beta 2-GPI antibodies were detected by ELISA in 32 of the 60 patients (53%). Significantly higher incidences of prolonged APTT and lupus anticoagulants were found in patients with these anti-beta 2-GPI antibodies. Moreover, significantly lower incidences of malar rash, serositis, LE cell preparation and anti-Sm antibodies were found in patients with these anti-beta 2-GPI antibodies. It was found that 88% of the patients with these anti-beta 2-GPI antibodies satisfied less than five of the revised criteria items for the classification of SLE. These findings indicate the clinical characteristics of APS patients with IgG phospholipid-dependent anti-beta 2-GPI antibodies.