| ANTIPHOSPHOLIPID
SYNDROME |
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Antiphospholipid antibodies and lupus
anticoagulant have been associated with retinal
vascular thrombosis. The antiphospholipid syndrome occurs
due to the presence of heterogeneous autoantibodies
that bind to negatively charged phospholipids. Manifestations
include venous and arterial thrombosis, fetal loss, and thrombocytopenia.
The mechanism by which vascular thrombosis occurs in some patients
with these antibodies is not completely understood, but the antibodies
may block endothelial cell thrombomodulin-mediated protein C activation.
The presence of antiphospholipid antibodies is most frequently
detected by a false positive test for syphilis, positive lupus
anticoagulant, and the presence of IgG anticardiolipin. The lupus
anticoagulant causes increased aPTT and Russel viper venom time. |
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