Acquired free protein S deficiency is associated with antiphospholipid antibodies and increased thrombin generation in patients with systemic lupus erythematosus

In order to determine whether there is a relationship between acquired free protein S deficiency and increased thrombin generation, we performed a cross-sectional study of patients with systemic lupus erythematosus (SLE). Plasma samples were assayed for free protein S and were correlated to levels of prothrombin fragments (F1 + 2); an elevated level of F1 + 2 was used as a surrogate marker for a prothrombotic state. Assays for anticardiolipin …