IgA Antiphospholipid Antibodies and Anti-Domain 1 of Beta 2 Glycoprotein 1 Antibodies are Associated with Livedo Reticularis and Heart Valve Disease in Antiphospholipid Syndrome.

Abstract

Antiphospholipid syndrome (APS) is an autoimmune disease associated with venous or arterial thrombosis and pregnancy loss, but also infrequently with non-criteria APS manifestations such as thrombocytopenia, livedo reticularis and heart valve disease. The occurrence of antiphospholipid antibodies is necessary to diagnose APS and includes the presence of lupus anticoagulant and anticardiolipin as well as anti-β2-glycoprotein Iantibodies, both in IgM and/or IgG isotype. The aim of this study was to evaluate the associations between antiphospholipid antibodies including IgA isotype and IgG anti-domain Iof β2-glycoprotein I(β-2GPI-D1) and non-criteria-related manifestations ofAPS. Thirty-three consecutive APS patients (26women, 7men, aged 44.1±15years), including 23 (69.7%) subjects with primary APS, were enrolled. Together with standard antiphospholipid antibodies, IgA anticardiolipin, IgA anti-β2-glycoprotein Iand IgG anti-β-2GPI-D1 antibodies in serum samples were evaluated by chemiluminescence using the QUANTA Flash® System. Livedo reticularis (n=8, 24.2%) was associated with increased levels of IgG anti-β-2GPI-D1 (p=0.005), IgA anticardiolipin (p=0.001) and IgA anti-β2-glycoprotein I(p=0.002) antibodies. Heart valve disease (n=9, 27.3%) was observed in patients with higher IgG anti-β-2GPI-D1 (p=0.01). The associations of HVD with increased levels of IgA aCL and IgA anti-β-2GPI tended to be significant (p=0.07). None of antiphospholipid antibodies showed association with thrombocytopenia (n=6, 18.2%). Our study suggests that increased IgA antiphospholipid antibodies and IgG anti-β-2GPI-D1 antibodies may be involved in the development of livedo reticularis and heart valve disease in APS patients.