Scientist of the European Vasculitis Study (EUVAS) group published the results of a recent study (Csernok et al., Autoimmunity Reviews 2016) testing the performance of two fully automated platforms for multiparametric ANCA IIFT diagnostics which combine cell substrates and monospecific antigen substrates: the EUROPLUS Granulocyte Mosaic (EUROPattern, Euroimmun AG) and CytoBead ANCA (Aklides, Medipan/Generic Assays GmbH).
The study included a panel of 249 samples from patients with ANCA-associated vasculitis (183 patients with granulomatosis with polyangiitis, 66 patients with microscopic polyangiitis) and 912 control samples. Automatically generated results were compared to those retrieved by manual immunofluorescence tests (IIFT), performed in two reference centers, and by monospecific ELISA (Anti-PR3-hn-hr-ELISA, Anti-MPO-ELISA, Euroimmun AG).
The results revealed that identification of c- and pANCA by EUROPattern was much more sensitive than by Aklides (sensitivity: 89% vs. 72%) at comparable specificities (90% vs. 89%). Furthermore, EUROPattern achieved a higher sensitivity (89% vs. 84%) and particularly (90% vs. 79%) a higher specificity (90% vs. 79%) than manual IIFT performed by a Danish reference center (Statens Serum Institut, Copenhagen) on just ethanol-fixed cells.
According to the authors’ conclusion the combination of ethanol- and formalin-fixed granulocytes, as it is applied in the reference center Bad Bramstedt and in the biochip mosaic, is better suited to identify vasculitis-associated ANCA patterns. The comparison of the automated platforms showed that EUROPattern is more efficient for this purpose. Furthermore, the authors confirmed that multiparametric diagnostics e.g. in the EUROPLUS mosaics, improves sensitivity and specificity of ANCA IIFT in vasculitis diagnostics.