Antiphospholipid antibodies are not present in the membrane of gel-filtered platelets of patients with IgG anticardiolipin antibodies, lupus anticoagulant and thrombosis.

To explore the possibility of an interaction between platelets and antiphospholipid antibodies and its relationship with thromboembolic events, platelets from six patients with IgG anticardiolipin antibodies, lupus anticoagulant and thrombosis were isolated by gel filtration. Five patients had primary antiphospholipid syndrome and one had a form secondary to systemic lupus erythematosus. Two patients had mild thrombocytopenia. The six platelet membrane eluates contained less than 1.09 GPL units of anticardiolipin antibodies and displayed no lupus anticoagulant activity. Similarly, lysates of disrupted platelets did not show anticardiolipin or lupus anticoagulant activity. These results suggest that antiphospholipid antibodies do not interact with circulating platelets, at least in patients on oral anticoagulant treatment with no evidence of acute thrombosis.