Standardisation Of Pr3-Anca And Mpo-Anca: Evaluation Of Certified Reference Materials

Antineutrophil cytoplasmic antibodies (ANCAs) are important laboratory markers to support the diagnosis of ANCA-associated vasculitis. A 2017 international consensus states that high-quality immunoassays for proteinase-3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA can be used as the primary screening method for patients suspected of having granulomatosis with polyangiitis or microscopic polyangiitis.1\n\nEfforts have been undertaken to standardise PR3-ANCA and MPO-ANCA measurements. More than 10 years ago, PR3-ANCA and MPO-ANCA reference standards have been prepared (from single patients) under the umbrella of the International Union of Immunological Societies (IUIS) and are available through the Autoantibody Standardization Committee (www.AutoAb.org). Several companies are using these reference standards (assigned value: 100 IU/mL) to calibrate their assays, such as Svar Life Science (ELISA), Thermo Fisher Scientific (fluoroenzyme immunoassay (FEIA)), Medipan (CytoBead assay) and Inova Diagnostics (chemiluminescence assay (CLIA)).\n\nThe Institute for Reference Materials and Measurements (IRMM) recently released certified reference materials for MPO-ANCA (ERM-DA476/IFCC) and for PR3-ANCA (ERM-DA483/IFCC).2 3 Both reference materials are based on plasmapheresis samples from single patients. We evaluated whether using the IRMM-certified reference materials aligns results for PR3-ANCA and MPO-ANCA across assays.\n\nA random selection of 98 serum samples covering low, medium and high PR3-ANCA or MPO-ANCA levels from the Leuven and the Maastricht cohort included in the international EUVAS study4 were distributed to five manufacturers, together with the PR3-ANCA and …