Lupus anticoagulant

Lupus anticoagulants (LA) are a heterogeneous class of immunoglobulins which has a paradoxical effect on coagulation: in vivo they are associated with recurrent thrombosis and in vitro they increase the phospholipid dependant clotting time (known as lupus anticoagulant activity) (1)

• lupus anticoagulant is an immunoglobulin, IgG or IgM, which binds to phospholipids and prevents coagulation reactions from taking place on the platelet surface
• associated with arterial and venous thrombosis, and recurrent spontaneous abortions

The LA anti-phospholipid often occurs in association with anti-cardiolipin antibodies (aCL) - 59% of patients with SLE having LA also have aCL, and 45% with SLE and aCL, also have LA.

• LA may be found in other autoimmune diseases, in response to drugs such as phenothiazine, and in patients with infectious diseases such as AIDS. Often, no underlying condition may be found.

Clinically theses antibodies are important:

• two systemic reviews have demonstrated that there is a strong association between lupus anticoagulant activity and thrombotic and obstetrics complications of the syndrome (1).
• LA is strongly associated with
  • venous thrombosis - both in SLE and in general population, this is much stronger in people <50 years
  • stroke - both in SLE and in general population, effect is much stronger in people <50 years
  • fetal loss at greater than 10 weeks' gestation (1)

Reference:

• (1) Cohen D et al. Diagnosis and management of the antiphospholipid syndrome. BMJ. 2010;340:c2541