Isolated elevation of IgA anti-β2glycoprotein I antibodies with manifestations of antiphospholipid syndrome: A case series of five patients

Current diagnostic classification criteria recommend elevated titres of anti-cardiolipin (aCL) and/or anti-β₂GPI antibody by ELISA IgG or IgM and/or lupus anticoagulant (LA) to confirm antiphospholipid syndrome (APS). Although IgA aPL antibodies have been shown to be pathogenic in animal models of APS, their clinical significance has remained elusive. We report four cases of exclusive IgA anti-β₂GPI antibody sero-positivity with concomitant clinical manifestations associated with APS. Four of the five patients were LA negative. 1) Thirty-eight-year-old African-American female with SLE presented with resolving digital ulcers. Serum IgA anti-β₂GPI antibody titres were 118.5 SAU (normal range: 0-20 SAU). 2) Twenty-seven-year-old African-American woman with SLE was evaluated for recent onset of severe headaches, unresponsive to analgesics and anti-migraine medications. MRI of the brain revealed hyper-intensities in the white matter in the frontal lobes. Serum IgA anti-β₂GPI antibody titres were 29.1 Standard A Units (SAU). 3) Thirty-two-year-old Hispanic female with history of two unexplained miscarriages and negative serologies for SLE. Serum IgA anti-β₂GPI antibody titres were 102.0 SAU. 4) Twenty-five-year-old white female with history of recent unexplained miscarriage in the 11th week of gestation and associated complaints of numbness and tingling in her hands. Her IgA anti-β₂GPI antibody titre was 62.0 SAU. 5) Twenty-five-year-old African-American woman with SLE, positive for anti-Ro antibodies with a history of ischemic fingers, a pregnancy loss and recent pregnancy complicated due to pre-eclampsia. Her LA was positive and her IgA anti-β₂ GPI antibody titer was 186.0 SAU. This case series supports that elevated IgA anti-β₂GPI antibody titres may identify additional patients who have clinical features of APS but who do not meet current diagnostic criteria.