Autoimmune MRL-1 pr/1pr mice are an animal model for the secondary antiphospholipid syndrome

Patients with systemic lupus erythematosus often develop thrombosis, recurrent abortion, thrombocytopenia and neurological disease, in association with serum antibodies against phospholipids, termed the secondary antiphospholipid syndrome. In our search for an animal model for the human antiphospholipid syndrome, we examined the MRL-1pr/pr mouse, which develops a lupus-like illness. These mice were found to have significantly elevated levels of serum antiphospholipid antibodies (aPL) and thrombocytopenia compared to normal mice. By immunodiffusion, these antibodies are similar to human aPL. We observed histologic evidence of central nervous system thromboses as well as perivascular infiltrates of the choroid plexus. The high titers of serum aPL, thrombocytopenia, and thrombosis establish this strain as an animal model for the secondary antiphospholipid syndrome.