Abstract

This report describes the production and certification of ERM-DA483/IFCC, a serum protein reference material intended for the standardisation of measurements of immunoglobulin G proteinase 3 anti-neutrophil cytoplasmic autoantibodies (IgG PR3 ANCA). The material was produced according to ISO Guide 34:2009 and is certified in accordance with ISO Guide 35:2006. The raw material used to prepare ERM-DA483/IFCC was a plasmapheresis material containing a high concentration of IgG PR3 ANCA. After a prior commutability study lyophilised serum was selected as the best format for the reference material. The processing of the serum was based on the procedure used for the reference material ERM-DA470k/IFCC . The plasma was converted into serum which was then delipidated. After the addition of preservatives the processed serum was diluted with plasmapheresis buffer containing albumin, prior to the transfer of 1 mL aliquots to glass vials. The serum was then lyophilised and the vials were closed with rubber stoppers and screw caps under argon atmosphere prior to storage at -70 °C. The between unit-homogeneity was quantified and stability during dispatch and storage was assessed in accordance with ISO Guide 35:2006. The material was characterised by an inter-laboratory comparison exercise performed by laboratories of demonstrated competence, using a purified IgG PR3 ANCA preparation as calibrant. This was achieved by applying a value transfer protocol previously used in the characterisation of ERM-DA470k/IFCC. Technically invalid results were removed, but no outliers were eliminated on statistical grounds alone. The uncertainty of the certified value was estimated in accordance to the Guide to the Expression of Uncertainty in Measurement (GUM) and included components relating to possible lack of homogeneity, stability and the property value measured during characterisation. The main purpose of this material is to be used for the calibration of immunoassay-based in vitro diagnostic devices or control products for IgG PR3 ANCA measurements. As any reference material, it can also be used for control charts or validation studies. The CRM is available in glass vials containing approximately 0.1 g of dried powder. The minimum sample intake to be used after reconstitution of the material is 5 μL. The CRM was accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium.