The C-ANCA (Cytoplasmic Anti-Neutrophil Cytoplasmic Antibody) test, more specifically known as the PR3-ANCA test, is a type of blood test used to detect autoimmune antibodies against Proteinase 3 (PR3) in the cytoplasm of neutrophils. This test is particularly used in diagnosing and monitoring systemic vasculitis diseases such as Granulomatosis with Polyangiitis (GPA or Wegener’s disease).
The C-ANCA pattern (diffuse cytoplasmic fluorescence) is observed using the Indirect Immunofluorescence (IIF) method. However, to confirm its specificity, the ELISA (Enzyme-Linked Immunosorbent Assay) method is used to detect anti-PR3 antibodies.
A positive result on this test, especially in combination with clinical symptoms such as vascular inflammation, respiratory, renal, or skin problems, can indicate disease activity. However, a positive PR3-ANCA result is rarely seen in other conditions such as Microscopic Polyangiitis or infections.
Interpretation of the results should be performed alongside clinical assessment, imaging, and sometimes tissue biopsy. This test plays a crucial role in early diagnosis, monitoring treatment response, and predicting disease relapse.
