Which antineutrophil cytoplasmic antibody (ANCA) pattern and target antigen are most commonly associated with granulomatosis with polyangiitis (Wegener granulomatosis)?

Question

Accepted Answer

A. c-ANCA with anti-PR3. ## ANCA Patterns in Granulomatosis with Polyangiitis (GPA)

**Key Point:** GPA is classically associated with **c-ANCA (cytoplasmic ANCA) targeting proteinase-3 (PR3)**, found in ~90% of generalized cases.

### ANCA Patterns and Target Antigens

| ANCA Pattern | Immunofluorescence | Target Antigen | Associated Vasculitis |
|---|---|---|---|
| **c-ANCA** | Cytoplasmic, central | **PR3 (proteinase-3)** | **GPA (Wegener)** |
| **p-ANCA** | Perinuclear, rim-like | **MPO (myeloperoxidase)** | **MPA, EGPA** |

### Pathophysiology
- **PR3** is a serine protease present in neutrophil azurophilic granules
- Anti-PR3 antibodies activate neutrophils → release of proteolytic enzymes → necrotizing vasculitis
- **c-ANCA pattern** results from the cytoplasmic distribution of PR3 antigen

**High-Yield:** 
- **GPA = c-ANCA/PR3** (remember: "GPA goes central")
- **MPA/EGPA = p-ANCA/MPO** (remember: "perinuclear for peripheral vasculitis")

**Mnemonic:** **CAGE**
- **C**-ANCA → **G**ranulomatosis with **P**olyangiitis (GPA)
- **P**-ANCA → **M**icroscopic **P**olyangiitis or **E**osinophilic **G**ranulomatosis with **P**olyangiitis (EGPA)

**Clinical Pearl:** c-ANCA/PR3 positivity is found in ~90% of generalized GPA (with pulmonary and renal involvement) but only ~50% of limited disease (e.g., upper respiratory only).

![Vasculitis Syndromes diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/2950.webp)

Answer

B. p-ANCA with anti-PR3

Answer

C. c-ANCA with anti-MPO

Answer

D. p-ANCA with anti-MPO

Which antineutrophil cytoplasmic antibody (ANCA) pattern and target antigen are most commonly associated with granulomatosis with polyangiitis (Wegener granulomatosis)?

Explanation

ANCA Patterns in Granulomatosis with Polyangiitis (GPA)

ANCA Patterns and Target Antigens

Pathophysiology

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ANCA Pattern	Immunofluorescence	Target Antigen	Associated Vasculitis
c-ANCA	Cytoplasmic, central	PR3 (proteinase-3)	GPA (Wegener)
p-ANCA	Perinuclear, rim-like	MPO (myeloperoxidase)	MPA, EGPA