Sensitivity of anti PR3 and anti MPO antibodies in patients with AAV
Sensitivity of Anti PR3 and Anti MPO Antibodies
The below table outlines the sensitivity of anti-PR3 and anti-MPO antibodies in AAV.
| Antibody Sensitivity (%) | |||
|---|---|---|---|
| Disease Entity | Anti-PR3 | Anti-MPO | Negative ANCA |
| Granulomatosis with polyangiitis (generalized) | 80–90 | 0–10 | 10 |
| Microscopic polyangiitis | 10–20 | 60–70 | 10–15 |
| Renal-limited vasculitis, pauci-immune glomerulonephritis | 20 | 64 | 15–20 |
| Eosinophilic granulomatosis with polyangiitis | 10 | 50 | 35–50 |
ANCA, Antineutrophil cytoplasmic antibody; MPO , myeloperoxidase; PR3 , proteinase 3.
Although the presence of c-ANCA associated with anti-PR 3 antibodies is quite specific (98%) for GPA, there are other AAV associations with the ANCAs, particularly MPA and RLV with pauci-immune necrotizing/crescentic GN. Interestingly, the glomerular lesions of these three disorders (GPA, MPA, RLV) are indistinguishable and are characterized by scant or no deposition of Ig (pauci-immune). Thus, these c-ANCA-associated pauci-immune disorders are a distinct category of autoimmune disease and can be clearly distinguished on biopsy (see Question 16) from immune complex disease (e.g., SLE) and antibasement membrane antibody disease (Goodpasture syndrome), which can also affect the kidneys (and lungs).
