Annexin V | Autoantibodies

General Information

Annexin V

This is a protein involved in cell membrane processes and the regulation of blood clotting. Autoantibodies to annexin V may be associated with antiphospholipid syndrome, thrombosis, and recurrent pregnancy loss.

Annexin V autoantibodies are antibodies directed against the Annexin V protein. Their determination is used in the evaluation of antiphospholipid syndrome, thrombotic complications, and recurrent pregnancy loss.

The test is often ordered in conjunction with other antiphospholipid antibodies, and interpretation of the results must be done in conjunction with clinical data and additional laboratory tests.

Annexin A-5 autoantibodies study as a second-line diagnostic method for antiphospholipid syndrome.

Antiphospholipid syndrome is an autoimmune disease clinically characterized by episodes of thrombosis and the presence of circulating antiphospholipid antibodies.

The presence of antiphospholipid antibodies may accompany rheumatoid arthritis, lupus erythematosus, or be a primary condition. Antiphospholipid antibodies are immunoglobulins directed against phospholipids on the membrane of platelets and endothelial cells and/or plasma proteins associated with these phospholipids.

The presence of at least one clinical and one laboratory criterion is necessary to confirm the antiphospholipid syndrome. Laboratory criteria include detection of the following antiphospholipid antibodies:

• Lupus anticoagulant (LA) – requires at least 2 determinations 12 weeks apart
• Cardiolipin autoantibodies (CA) – IgM and IgG >40 GPL/MPL with a titer requiring at least 2 determinations 12 weeks apart
• Anti-β2-glycoprotein antibodies – with increasing IgM and IgG titers, require at least 2 determinations with an interval of 12 weeks

It is necessary to detect all three types of antibodies simultaneously. If no type of autoantibody is detected, the presence of antiphospholipid syndrome is unlikely. The coexistence of different antibodies is often associated with a severe course of the disease.

There are frequent cases when the data of repeated serological research are negative, however, the clinical condition indicates antiphospholipid syndrome. In such situations, determination of second-line serological markers is used, one of which is anti-annexin antibodies.

The annexin family consists of 12 proteins that have the ability to bind to anionic phospholipids.

Annexin 5 has natural anticoagulant properties and is found mainly in trophoblastic and endothelial cells. It prevents the development of the coagulation cascade, thus causing an anticoagulant effect.