ANTIPLATETLET ANTIBODIES IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS AND THE PRIMARY ANTIPHOSPHOLIPID ANTIBODY SYNDROME - THEIR RELATIONSHIP WITH THE OBSERVED THROMBOCYTOPENIA

The role of antiphospholipid antibodies in the pathogenesis of the thr ombocytopenia observed during primary antiphospholipid antibody syndro me (APAS) and systemic lupus erythematosus (SLE) remains controversial , We have used the MAIPA test to examine the frequency and specificity of anti-platelet antibodies directed against the major platelet membr ane glycoproteins (GP IIb-IIIa, GP Ib-IX, GP Ia-IIa and GP TV) in pati ents where SLE and APAS were associated or not with thrombocytopenia. Results were compared with a series of 26 ITP patients, 46% of whom we re shown to possess anti-platelet antibodies directed against one or m ore of the platelet surface glycoproteins. When APAS was associated wi th thrombocytopenia, 7/10 patients possessed antibodies against GP IIb -IIIa and/or GP Ib-M. For SLE patients with thrombocytopenia, 6/10 pat ients were shown to have antiplatelet antibodies against GP IIb-IIIa, GP Ib-IX or GP IV. In contrast, for APAS (n=11) and SLE patients (n=11 ) without thrombocytopenia, only one patient had an antibody directed against GP IIb-IIIa and one patient had an antibody to GP IV. Our resu lts suggest that antibodies directed against major platelet membrane g lycoproteins may play a role in the thrombocytopenia that is seen duri ng SLE and APAS.