Vasculitis

AAV diagnostics relies predominantly on the monospecific detection of antibodies against proteinase 3 (PR3) and myeloperoxidase (MPO), as well as the detection of ANCA using IIFT. According to the international consensus of 2017, the use of high-quality monospecific assays is particularly recommended for the detection of PR3 and MPO in the context of GPA, MPA and EGPA diagnostics.

With the innovative Anti-PR3-hn-hr ELISA, consisting of a mixture of human native (hn) and human recombinant (hr) PR3, as well as the Anti-MPO ELISA with highly purified human MPO, EUROIMMUN offers high-quality test systems to support the diagnosis in suspected AAV. Especially the Anti-PR3-hn-hr ELISA is characterised by a very good specificity (99 %) and a significantly higher sensitivity (94%) compared to ELISAs using native antigens (88 % and 78 %, respectively).

EUROIMMUN offers BIOCHIPs consisting of ethanol (EOH)- and formaldehyde (HCHO)-fixed human granulocytes, which represent the standard substrate for IIFT diagnostics. Further EUROIMMUN-exclusive BIOCHIPs, e. g. HEp-2 cells with sedimented granulocytes, further increase the diagnostic certainty. The EUROPLUS technique allows the combination of conventional cell culture substrates with defined, purified single antigens (PR3, MPO, GBM) on one test field. This considerably simplifies the interpretation of the immunofluorescence patterns.

By means of IIFT, two ANCA types can be displayed: One is the cytoplasmic type (cANCA), which is associated with GPA and is almost always directed against PR3, and the other is the perinuclear type (pANCA), which indicates a spectrum of different diseases. The main target antigen of pANCA is mainly MPO in MPA and EGPA. In addition, there are atypical ANCA (also called xANCA or DNA-ANCA), which are particularly associated with chronic inflammatory bowel diseases (CIBD) and liver diseases (primary biliary cholangitis (PBC) or primary sclerosing cholangitis (PSC)). Prominent representatives of these ANCA include those directed against DNA-linked lactoferrin, cathepsin G, lysozyme or BPI. Positive IIFT results should always be interpreted in combination with a monospecific anti-PR3 and anti-MPO test (e. g. ChLIA or ELISA). Since not all cANCA and pANCA are positive in the monospecific test, only a combination of IIFT and ChLIA/ELISA achieves high specificity and sensitivity for ANCA detection. EUROIMMUN offers ELISA, EUROLINE, ChLIA and IIFT test systems for the detection of ANCA and antibodies against PR3, MPO and GBM.