ERM-DA483/IFCC: A new certified reference material for autoimmune antibodies
JRC releases a new serum protein certified reference material which has been developed in collaboration with the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) for the standardisation of measurements of immunoglobulin G proteinase 3 anti-neutrophil cytoplasmic autoantibodies (IgG PR3 ANCA). These antibodies represent the cornerstones of the diagnosis and monitoring of small vessel-associated vasculitis together with IgG MPO ANCA.
Small-vessel associated vasculitis includes three distinct forms; granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA). Despite their common characteristics, they cannot be diagnosed with the same biomarker.
IgG PR3 ANCA are found in about 80% of patients with GPA. The newly developed CRM (ERM®-DA483/IFCC) serves as a biomarker mostly for this disease subform and it was developed so as to complete the gap that was left after the release of our previous CRM against IgG MPO ANCA (a biomarker mostly for the detection of MPA and EGPA).
Despite the importance of autoimmune antibodies in laboratory medicine and their routine analysis, the diversity in the measurement results from different methods remains vast. The immunoassays used for such measurements can be sensitive and specific, and are convenient in a clinical setting. However, the measurement signal is depending on a large number of factors such as antibody specificity, reaction kinetics and equilibria, multimeric state of the proteins, matrix effects, etc. Therefore the quantification with immunoassays requires the use of a well-designed and carefully characterised calibrant.
The EU Directive on In Vitro Diagnostic Medical Devices (IVD-MD) (Directive 98/79/EC) requires traceability of calibrants and control materials to reference measurement procedures and/or reference materials of higher order. There are already materials designated for calibration, but they are not fully characterised and often inconsistently used. This generates large variability in the measurement results and a potential delay in the diagnosis and subsequent follow-up of the disease.
The new reference material ERM®-DA483/IFCC was processed, characterised and certified in accordance to ISO Guide 34:2009. An inter-laboratory comparison exercise was performed with adherence to the quality requirements of ISO/IEC 17025. Details about material sampling, processing, characterisation and certification are described in the certification report, available together with the certificate in our online catalogue.