Annexin V | Autoantibodies

General Information

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.

Antiphospholipid antibodies prevent binding of phospholipids to annexin5, which accelerates coagulation reactions and thrombotic processes. Annexin is actively produced by the placenta and is a necessary component to maintain its integrity.

An elevated titer of anti-annexin antibodies is observed in 20-30% of cases of systemic lupus erythematosus. Also, these antibodies are associated with antiphospholipid syndrome, in which repeated thrombosis and cases of pregnancy termination occur.

When is the survey conducted?

• Determination of anti-annexin 5 antibodies is important in seronegative antiphospholipid syndrome when first-line autoantibodies are not detected.
• Recurrent thromboses in young people when other causes are excluded.
• Repeated termination of pregnancy at 10 weeks or more, with normal fetal morphology; Termination of more than 3 pregnancies before 10 weeks; as well as one or more premature births in the anamnesis;
• In the presence of systemic diseases - especially systemic lupus erythematosus
• In unexplained thrombocytopenia

Patient preparation –  It is not necessary

study material –  Venous blood

Referral norm – Antibodies against annexin 5 - negative

When receiving a positive response to antibodies against annexin 5, it is necessary to repeat the study in 12 weeks. Research data should be interpreted in correlation with the clinical picture.