Inhibition of heparin/antithrombin III cofactor activity by anticardiolipin antibodies: a mechanism for thrombosis

Anticardiolipin antibodies (aCL) are autoantibodies which react with negatively charged phospholipids and are associated with thrombotic disease and recurrent fetal loss. We have found that 11% of aCL are cross-reactive with the glycosaminoglycans heparin and heparan sulphate. One of these antibodies was studied in detail and was found to inhibit the heparin dependent activation of antithrombin III by up to 80%. The inhibition of heparin dependent antithrombin III activation represents a new mechanism by which anticardiolipin antibodies may induce thrombosis or fetal loss in some patients with these antibodies.