Abstract
The diagnosis of antiphospholipid syndrome (APS) relies on the detection of circulating
antiphospholipid antibodies (aPL). Currently, lupus anticoagulant (LA), anticardiolipin
(aCL), and anti-β2-glycoprotein I antibodies (aβ2GPI) IgG or IgM are the laboratory
criteria if persistently present over time. As aCL and aβ2GPI are two out of the three
laboratory criteria, the detection of aPL by solid phase assays is an essential step
in the diagnosis of APS. Advancement has been made to resolve some of the methodological
challenges of aCL and aβ2GPI assays by providing guidelines how to measure aPL, as
well as to gain a better understanding of their diagnostic role. However, solid phase
assays for aCL and aβ2GPI still show substantive inter-assay differences, resulting
in disagreement concerning positive/negative results, but also differences in titer
of antibodies. This hampers the semiquantitative classification into low-medium-high
positivity. The non-criteria aPL, such as antibodies against the domain one of β2GPI
and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have roles in confirming
the risk in APS, and can be useful, especially in patients with incomplete antibody
profiles.
Keywords
antiphospholipid syndrome - anticardiolipin antibodies - anti-β2-glycoprotein I antibodies
- prothrombin - β2-glycoprotein I - interference - classification