Introduction
The antiphospholipid (aPL) syndrome is a condition that manifests in patients as vascular
thromboembolism or recurrent pregnancy loss together with laboratory evidence for
the presence of antibodies against anionic phospholipid-protein complexes. For a recent
comprehensive review, the reader is referred to Hughes et al.1 The syndrome was first proposed to be a distinct entity, called anticardiolipin syndrome,
in 1985,2 and was later renamed antiphospholipid syndrome.3 The disorder was classified as “primary” in the absence of a concurrent autoimmune
condition, such as systemic lupus erythematosus, or “secondary” in the presence of
another such autoimmune disorder. Antiphospholipid antibodies are detected by their
reactivity to anionic phospholipids (or protein-phospholipid complexes) in solid phase
immunoassays, or by their inhibition of phospholipid-dependent coagulation reactions,
known as the “lupus anticoagulant” effect. The ever-expanding, yet still insufficiently
integrated, knowledge of this enigmatic disorder makes this area an intriguing subject
for investigation.
The pathophysiologic mechanism of this syndrome has remained obscure, resulting from
the apparent multiplicity of antigenic determinants recognized by the antibodies.
In addition, a large number of effects1 have been described for the antibodies in vitro and in cell culture systems. These
effects, which include the paradoxical lupus anticoagulant (LAC) phenomenon, are a
consequence of the numerous roles played by phospholipids in the hemostasis system
and in a multitude of biologic processes. The purpose of this review is to introduce
the reader to the current state of knowledge of the role of annexin-V in this disorder.
