AUTOIMMUNE CARDIOLIPIN‐BINDING ANTIBODIES IN ORAL ANTICOAGULANT PATIENTS

Abstract

In a routine clinic of patients taking regular oral anticoagulant therapy (warfarin, n = 140) 14% were found to have elevated levels (> 4 SD above normal) of anticardiolipin antibody (ACA) assessed by a well standardised enzyme linked immunosorbent assay (ELISA). There was a higher incidence of raised ACA in patients being treated for thrombotic episodes (9/47 = 19%) than in cases with heart valve replacements (8/75 = 11%). Furthermore, the highest ACA titres were in younger patients with thromboses scheduled for short-term anticoagulant treatment. Borderline DNA binding studies, together with some positive ANA results, suggested autoimmune etiology in the minority of these cases. Lupus anticoagulant was strongly detectable in only one such patient. The ACA were predominantly IgG (14/17) and did not appear to compromise the conditions of patients while on anticoagulant therapy. Raised ACA may be a highly significant marker for an acquired prothrombotic state.