SERUM ANTIBODIES TO DISTINCT EPITOPES OF THE TISSUE-TYPE PLASMINOGEN-ACTIVATOR (T-PA) IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Defective fibrinolysis due to decreased tissue-type plasminogen activa tor (t-PA) activity is a well established finding in patients with sys temic lupus erythematosus (SLE). The possibility that this decrease in t-PA activity may be related to the presence of autoantibodies direct ed against t-PA, and the possible role of these autoantibodies in the pathophysiology of fibrinolysis in SLE, were investigated, Serum sampl es from 115 SLE patients and 63 normal volunteers were analyzed for th e presence of such antibodies. The search for antibodies to t-PA was p erformed by means of several systems, allowing for the identification of epitopes presented in different conformational physical states of t -PA: free or associated to its inhibitor (PAI-1) in plasma, specifical ly bound to fibrin surface, or passively adsorbed to solid supports, A ntibodies in variable amounts were detected by all systems used; howev er, BPA activity was not inhibited by the IgG fraction of the positive sera in a fibrin-agar fibrinolysis system, Moreover, the demonstratio n of serum anti-t-PA antibodies was not associated with clinical or la boratory abnormalities related to vasoocclusive episodes, These result s indicate that, as in the case of other autoantibodies, their detecti on in serum does not imply their direct participation in the pathophys iology of thrombosis in SLE. (C) 1995 Wiley-Liss, Inc.