β-2 Glycoprotein-I IgA

Anti-phospholipid antibodies (aPL) are a group of immunoglobulins associated with binding of negatively charged phospholipids including cardiolipin and phosphatidyl serine. High serum levels of anti-phospholipid antibodies are frequently found in patients with recurrent arterial and venous thromboembolism , recurrent foetal loss and thrombocytopenia, the main features of anti-phospholipid syndrome (APS). These symptoms are also often present in cases of Systemic Lupus Erythematosis (SLE), when elevated levels of aPL are detected.

It has been reported that β-2-Glycoprotein I (β2-GPI), a 50 kD plasma protein, is required for binding of anti-cardiolipin and anti-phospholipid antibodies and was more recently found to be the target for a specific group of aPL. The conformational epitope for anti-β-2GPI antibodies is thought to develop when β2-GPI interacts with a lipid membrane composed of negatively charged phospholipids or, more recently reported, when it is adsorbed to the surface of a polystyrene microtitre plate.

Antibodies targeting β-2-GPI specifically have been found to be the dominant autoanitbody type in anti-phospholipid positive sera and is widely accepted as a clear diagnostic indicator of APS and of SLE associated with APS.

To increase the efficiency of clinical laboratory testing for APS, anti-cardiolipin IgM and IgG, β-2-GPI IgM and IgG ELISAs are also available from Hycor Biomedical.