The role of phospholipids

In antiphospholipid syndrome, your body mistakenly produces antibodies against proteins that bind phospholipids, a type of fat present in your blood that plays a key role in clotting (coagulation). Antibodies are specialized proteins that normally attack body invaders, such as viruses and bacteria. When antibodies attack your phospholipid-binding proteins, your blood may clot abnormally.


There are two main classifications of antiphospholipid syndrome:

  • Primary. If there's no known underlying reason, such as an autoimmune disorder, you have primary antiphospholipid syndrome.
  • Secondary. If you have systemic lupus erythematosus or another autoimmune disorder, certain infections, or have taken certain medications, your antiphospholipid syndrome is secondary. The cause of your antiphospholipid syndrome is considered to be the underlying condition or medication.

Some factors are associated with developing antiphospholipid antibodies — though not necessarily with developing the syndrome. They include:

  • Infections. People with certain infections, including syphilis, HIV infection, hepatitis C and Lyme disease, among others, have a higher incidence of having antiphospholipid antibodies.
  • Medications. The high blood pressure medication hydralazine, the heart rhythm-regulating medication quinidine, the anti-seizure medication phenytoin (Dilantin) and the antibiotic amoxicillin may lead to an increased risk of developing antiphospholipid antibodies.
  • Genetic predispositions. Although the disorder isn't considered hereditary, research indicates that relatives of people with antiphospholipid syndrome are more likely to have the antibodies.
April 15, 2014