Oxidized low-density lipoprotein β2-glycoprotein I complexes and autoantibodies to oxLig-1 β2-glycoprotein I in patients with systemic lupus erythematosus and antiphospholipid syndrome

Oxidized low-density lipoprotein (oxLDL) interacts with beta(2)-glycoprotein I (beta(2)-GPI) via oxLDL-derived specific ligands (oxLig-1)forming complexes. The prevalence and significance of oxLDL/beta(2)-GPI complexes and antibodies to oxLig-Ybeta(2)-GPI were evaluated in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The oxLDL/beta(2)-GPI complex was 69% positive (above mean + 3 SD of control subjects) in 97 consecutive patients with SLE, % in 40 patients with SLE with secondary APS, and 60% in 50 control patients with SLE without APS. IgG anti-oxLig-1/beta(2)-GPI antibody was positive in 31 (32%) of 97 consecutive patients with SLE, in 26 (65%) of 40 patients with SLE with secondary APS, and in 6 (19%) of 32 control patients with SLE. Anti-oxLig1/beta(P)2-GPI antibodies were 93.7% specific with a positive predictive value of 90.0% for APS, better than anticardiolipin antibodies (80.0% specific, 71.4% predictive value). These results confirm that oxLDL/beta(2)GPI complexes are common in SLE and suggest a possible immunogenic role in APS. In contrast, IgG anti-oxLig-1/beta(2)-GPI antibodies not only are associated with but also are clinically useful risk factors for APS.