Standards and reference materials for the anticardiolipin and anti-β2glycoprotein I assays: a report of recommendations from the APL Task Force at the 13th International Congress on Antiphospholipid Antibodies.

BACKGROUND: The confirmation of diagnosis of the Antiphospholipid Syndrome (APS) relies on laboratory tests. Current classification criteria for definite APS mandate the use of three "standardized" laboratory assays to detect antiphospholipid antibodies (aPL) [viz: anticardiolipin (aCL) IgG and IgM, anti-β(2)glycoprotein I (anti-β(2)GPI) antibodies IgG and IgM and/or a lupus anticoagulant (LAC)], when at least one of the two major clinical manifestations (thrombosis or pregnancy losses) are present. Several attempts have been made to standardize the aCL and anti-β(2)GPI tests, though, a considerable degree of inconsistencies still exist, limiting the clinical and diagnostic value of aPL tests. Among the areas of concern are the type and source of calibrant material, the lack of proper validated reference material and of universal units of measurement, particularly for anti-β(2)GPI antibodies. CONTENT: A Task Force of scientists and leaders in the field from different countries - discussed and analyzed those critical questions in an evidence-based manner and further discussed and made recommendations at a workshop that was conducted during 13th International Congress on Antiphospholipid Antibodies (APLA 2010, April 13-16, 2010, Galveston, TX).
SUMMARY: This concise report summarizes the findings, conclusions and recommendations of the task force and preconference workshop. The group recommended to ensure the availability of properly prepared and validated polyclonal and monoclonal antibody reference materials for both assays, to continue reporting the aCL assay in GPL/MPL units and to establish consensus international units of measurement for anti-β(2)GPI antibodies.