Standardization of antiphospholipid antibody assays. Where do we stand?

The laboratory criteria (lupus anticoagulants (LA), and/or anti-cardiolipin (aCL) antibodies and/or anti-β2-glycoprotein I antibodies (aβ2GPI)) that define patients with antiphospholipid syndrome (APS) were set in the Sapporo and Sydney criteria published in 1999 and 2006, respectively, and led to a substantial improvement in the recognition of APS. In addition, guidelines for LA detection were published by the Scientific Standardisation Subcommittee (SSC) of the International Society of Thrombosis and Haemostasis (ISTH) in 2009. However, a number of questions on this respect remain unresolved. Recommendations for the aCL and aβ2GPI assays intended to ameliorate the performance of these solid-phase assays. Despite efforts over the years, standardization has not been reached. This review will focus on methodological issues of the three antiphospholipid antibody (aPL) subtypes that are the subject of debate. The use of an international standard for aPL detection might help solve many of the problems caused by a lack of standardization of these assays.