LUPUS ANTICOAGULANT AND THROMBOSIS - ROLE OF VON-WILLEBRAND-FACTOR MULTIMERIC FORMS

Objective. Patients with lupus anticoagulant (LA) have an increased in cidence of venous and arterial thrombosis whose pathogenesis is still unclear. High molecular weight von Willebrand Factor (vWF) multimers s eem to play a causal role in shear stress-induced platelet aggregation and thrombus formation. We studied whether in patients with LA, alter ations in the vWF multimers might coexist. Methods. The multimeric com position of plasma vWF was analysed by SDS-electrophoresis and immunob lotting in 43 subjects positive for LA. About 2/3 of the patients had had either ischemic stroke, recurrent abortions, deep vein thrombosis (DVT) or a combination of these; the remaining subjects had never had any thrombotic events. Results. An abnormal vWf multimeric pattern was found in 16 patients (37.2%); no correlation was found with the diagn osis, but the presence of abnormal vWF significantly correlated with t he site of the thrombosis: indeed, it was never detected in subjects w ith DVT, but was found in 71.4% of patients with multiple abortions, i n 50% of those with stroke and even in 25% of non-thrombotic patients. Conclusion. The hypothesis is put forward that abnormal VWF may repre sent an additional risk factor to LA for arterial thrombosis.