A Monocentric Cohort of Obstetric Seronegative Anti-Phospholipid Syndrome

The present study was conducted to diagnose obstetric antiphospholipid syndrome (OAPS) in patients with clinical signs suggestive of antiphospholipid syndrome (APS), but persistently negative for conventional anti-phospholipid antibodies (aPL). Sera from 61 obstetrical seronegative APS (SN-APS) patients were analysed for anti-cardiolipin antibodies (aCL) using TLC-immunostaining, for anti-cardiolipin/vimentin antibodies (aCL/Vim), anti-phosphatidylserine/prothrombin antibodies (aPS/PT), IgA anti-β2glycoprotein I antibodies (aβ2GPI) and IgA aCL antibodies by enzyme-linked immunosorbent assay (ELISA). Taken together, our findings show that in 50 out of 61 SN-APS (81.9%) at least one aPL/cofactor antibody was detected using the assays under test. Results revealed that 76% of SN-APS patients resulted positive for aCL by TLC-immunostaining, 54% for aCL/Vim, 12% for aPS/PT, 4% for IgA aβ2GPI and 2% for IgA aCL. Thirty-five out of 61 patients were followed up and the tests were repeated on two occasions, at least 12 weeks apart. Twenty-six out of 35 SN-APS (74.3%) were positive at least one non-conventional test; only 2 patients (5.7%) did not confirm the positivity to the second test. These findings suggest that non-conventional test, mainly aCL/Vim and aCL detected by TLC-immunostaining seem to be the most sensitive approaches for finding out aPL in patients with obstetric SN-APS. Since a diagnosis of APS is required to direct physicians to treatments that significantly improve the birth rate, this work has important therapeutic and prognostic implications.