Association of IgA anti-ß2 glycoprotein i with clinical and laboratory manifestations of systemic lupus erythematosus

Objective: IgA isotypes of anticardiolipin and anti-ß₂ glycoprotein I (anti-ß₂-GPI) are omitted from the revised antiphospholipid syndrome (APS) classification criteria. Multiple studies have found a high prevalence of IgA anti-ß₂-GPI in systemic lupus erythematosus (SLE). We determined the frequency and associations of IgA anti-ß₂-GPI in a cohort of patients with SLE. Methods: Anti-ß₂-GPI was measured in 796 patients with SLE (93% women, 53% white, 38% African American, mean age 45 yrs). IgA anti-ß₂- GPI (> 20 phospholipid units) was found in 20%. Using a cohort database, associations with cumulative thrombotic and other manifestations were determined. Results: Of patients with SLE who demonstrated IgA anti-ß²-GPI positivity, about 6% had transient ischemic attack (p = 0.070), 4% had superficial thrombophlebitis (p = 0.647), 20% had deep venous thrombosis (p = 0.003), 4% had other venous thrombosis (p = 0.827), 12% had stroke (p = 0.050), and 1% had myocardial infarction (p = 0.397). Conclusion: IgG anti-ß₂-GPI has the strongest association with thrombosis in SLE. However, IgA anti-ß₂-GPI was more strongly associated with deep venous thrombosis and with stroke than was IgM. These results indicate that assessment of IgA anti-ß₂-GPI is associated with thrombosis in SLE, and that the classification criteria for APS should be revised to include IgA anti-ß₂-GPI in patients with SLE.