Antibodies to tissue-type plasminogen activator in plasma from patients with primary antiphospholipid syndrome

A reduction in flbrinolysis has been described in association with thrombos is in the primary antiphospholipid syndrome (PAPS), In this study, we measu red antitissue-type plasminogen activator (t-PA) antibodies and anti-fibrin -bound t-PA antibodies as possible causes of hypofibrinolysis in 39 patient s with PAPS. We also evaluated the differences in anti t-PA antibodies betw een patients without previous thrombosis (20 patients) and patients with pr evious episodes of thrombosis (19 patients: deep vein thrombosis in nine, i schaemic stroke in six, arterial leg thrombosis in one, hepatic vein thromb osis in one, thrombophlebitis in one and cerebral venous thrombosis in one) . Anti-t-PA antibodies were measured by an enzyme-linked immunosorbent assa y (ELISA), and anti-t-PA fibrin-bound antibodies were measured by a solid-p hase fibrin immunoassay (SOFIA) in 39 patients with PAPS and in 39 controls matched for gender and age. High levels of IgG anti-t-PA were found in thr ee out of 39 patients with PAPS, and ail three patients had a history of th rombosis; four other patients, one of whom had a history of thrombotic even ts, had high titres of antibodies directed against fibrin-bound t-PA. In ad dition, patients with ischaemic stroke had significantly higher levels of I gG anti-t-PA than patients without: thrombosis (P = 0.029). In conclusion, our data showed that, in patients with PAPS, the highest levels of anti-t-P A antibodies were present in subjects with previous thrombotic events. The discrepancy in the results obtained with two methods of detection of anti-t -PA antibodies, ELISA and SOFIA, indicates a different interaction of the a ntibodies with the t-PA molecules, which are directly bound to polystyrene plates in ELISA and bound to fibrin as a bridging molecule in SOFIA.