Vasculitides are disorders in which blood vessels are destroyed by inflammation. The diagnosis of vasculitides is based on histology and laboratory testing. Anti-Neutrophil Cytoplasmic Antibody (ANCA) tests supplement the diagnosis of small-vessel vasculitides.
International consensus states that indirect immunofluorescence assays (IFA) should be carried out on all samples of new patients. An ELISA test is then used to provide confirmation. The combination of these two tests typically provide enough information for a confident diagnosis.
- Allow differentiation to other vasculitides
- Help in confirmation of diagnosis
- Enable early detection
- Quantitative tests help monitor inflammation activity (useful for prediction of relapse)
International consensus states that indirect immunofluorescence assays (IFA) should be carried out on all samples of new patients. An ELISA test is then used to provide confirmation. The combination of these two tests typically provide enough information for a confident diagnosis.
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ANCA screening by ifaEuroimmun's Granulocyte Mosaic 13 is designed for the qualitative or semi-quantitative in-vitro determination of human IgG antibodies against ANCAs.
IFA tests are considered the gold standard for detection of ANCAs. Euroimmun's BIOCHIP technology enables the combination of conventional substrates with defined individual antigens in one test field. This simplifies the interpretation of the IFA patterns considerably. Each BIOCHIP contains three fields:
Laboratories may also select a BIOCHIP with MPO and PR3 antigen dots (FA-1201-32), or with MPO, PR3, and GBM (FA-1201-25). The BIOCHIP is coated with microscopically small droplets of highly purified antigens, and fluorescence is observed if the sample contains antibodies directed against these antigens. Slides may be read automatically on the EUROPattern microscope. |
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A 2014 paper by Lin et al (Westmead Hospital, Australia) published in the American Journal of Clinical Pathology showed that formalin-fixed granulocytes improve the sensitivity and specificity of ANCA testing.
The distinction between typical and atypical pANCA using formalin fixation improved the sensitivity and specificity of ANCA testing. |
The use of formalin-fixed neutrophils overcomes the problem of interference from antinuclear antibodies, which give a pANCA pattern on the ethanol-fixed neutrophil substrate, but are negative on formalin-fixed neutrophils. |
Concomitant staining on formalin fixation of IIF-positive ethanol-fixed ANCA samples improves the interpretation of ANCA testing and is predictive of vasculitis autoantigens MPO and PR3. |
