An ANCA panel is a blood test that detects antineutrophil cytoplasmic antibodies (ANCAs), which are autoantibodies associated with certain autoimmune diseases, primarily vasculitis. The test includes both indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA) to identify specific ANCA patterns and types.
The ANCA panel uses two primary methods to detect ANCAs:
First, blood is drawn and centrifuged to separate serum. The serum is then applied to slides containing neutrophils for IFA or to ELISA plates coated with PR3 or MPO. Fluorescent dye or enzyme reactions reveal the presence and pattern of ANCAs.
The ANCA panel typically includes several components:
| Test Component | Purpose |
|---|---|
| Indirect immunofluorescence assay (IFA) | Identifies c-ANCA and p-ANCA patterns |
| Proteinase 3 (PR3) ELISA | Quantifies PR3-ANCA, associated with granulomatosis with polyangiitis (GPA) |
| Myeloperoxidase (MPO) ELISA | Quantifies MPO-ANCA, associated with microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA) |
Each component provides distinct information about the type and severity of autoimmune activity.
The ANCA panel is primarily used to diagnose and monitor vasculitis, a group of autoimmune diseases that cause inflammation of blood vessels. Common conditions include:
According to the American College of Rheumatology, ANCA testing is essential for differentiating between these conditions and guiding treatment decisions.
For example, a patient with suspected vasculitis might first undergo an ANCA screen. If positive, an ANCA panel would follow to determine whether the patient has PR3-ANCA or MPO-ANCA, guiding further treatment.