[National external quality assessment in auto-immunity: antineutrophil cytoplasmic antibodies]

The French Health Products Safety Agency organized in 2007, for the scheme of the national external quality assessment, a survey on antineutrophil cytoplasmic antibodies (ANCA) including detection and identification of the antibodies. This survey allowed to assess the quality of the different methods of these assays. The detection of ANCA by the indirect immunofluorescence technique was satisfactory. However, the methods of identification gave a high rate of false negative results for the anti-myeloperoxidase antibodies (anti-MPO), especially with the immunodot technique. Concerning the titer of anti-MPO antibodies obtained by ELISA, the broad dispersion of results between reagents pointed out a lack of standardisation of the detection of these antibodies.