Anti-phospholipid syndrome

Anti-phospholipid syndrome (APS) is a systemic autoimmune disease in which circulating anti-phospholipid antibodies (APLA) play a central role. The disease is characterised by arterial, venous or microvascular thrombosis and pregnancy complications such as pre-eclampsia, premature birth or spontaneous abortion. APS can also have non-thrombotic manifestations, such as valvular heart disease or thrombocytopenia.

According to the current ACR/EULAR classification criteria of the American College of Rheumatology (ACR) and the European Alliance of Associations for Rheumatology (EULAR) of 2023 (Barbhaiya et al. 2023), classification as APS requires that the entry criteria, which include clinical manifestation and positive APLA within three years, are met. For APS classification, an additional 3 points must be accumulated from each of the different clinical manifestations and from the different serological tests.  These laboratory tests include the lupus anticoagulant (LA) test and the detection of APLA: anti-β2 glycoprotein-1 (β2GP1) antibodies and anti-cardiolipin antibodies (ACA) of the immunoglobulin classes G and M. The international consensus guidelines (Lakos et al., 2012) recommend that IgA should also be tested if an IgG and IgM test for ACA or anti-β2GP1 is negative. Antibodies against phosphatidylserine have also been shown to be significantly associated with APS (Khogeer et al., 2015). These and other APLA are part of ongoing studies and further research into their clinical relevance in APS (Devreese KMJ., 2024).