Abstract
Antiphospholipid syndrome (APS) is a systemic autoimmune disorder caused by the presence
of aPLs (antiphospholipid antibodies, i.e., anti-β2-glycoprotein I and anti-cardiolipin). Everyday practice in terms of laboratory diagnostics
of APS includes determination of aPLs and well-known functional assays assessing for
lupus anticoagulant (LA), in turn using various tests. According to recent guidelines,
the recommended method for LA identification or exclusion is based on the Russell
Viper Venom test and a sensitive activated partial thromboplastin time assay. Despite
the fact that LA can be quantified in laboratory practice in this way, LA is still
used as a binary parameter that is just one of the risk factors of thrombosis in APS.
As of today, there are no other functional assays to routinely assess the risk of
thrombosis in APS. It is well-known that APS patients display a wide range of clinical
outcomes although they may express very similar laboratory findings. One way to solve
this dilemma, could be if antibodies could be further delineated using more advanced
functional tests. Therefore, we review the diagnostic approaches to test the function
of aPLs. We further discuss how thrombin generation assays, and rotational thromboelastometry
tests can be influenced by LA, and how experimental methods, such as flow cytometric
platelet activation, surface plasmon resonance, or nano differential scanning fluorimetry
can bring us closer to the puzzling interaction of aPLs with platelets as well as
with their soluble protein ligand. These novel approaches may eventually enable better
characterization of aPL, and also provide a better linkage to APS pathophysiology.
Keywords
antiphospholipid syndrome - anti-β
2GPI - functional assay
