Coexistence of anti-glomerular basement membrane antibodies and myeloperoxidase-ANCAs in crescentic glomerulonephritis

BACKGROUND: In a substantial proportion of patients with crescentic glomerulonephritis (CGN), both anti-glomerular basement membrane (GBM) antibodies and antineutrophil cytoplasmic antibodies (ANCAs) with specificity for myeloperoxidase (MPO-ANCA) are detected. In the present study, we questioned whether histological and clinical features of patients with both ANCA and anti-GBM antibodies differ from those of patients with either ANCA or anti-GBM alone.

METHODS: We reviewed the Limburg renal biopsy registry (1978 to 2003; n = 1,373) for cases of CGN. The presence of linear fluorescence on renal biopsy and the presence of ANCA and/or anti-GBM antibodies were measured. Subsequently, we assessed patient characteristics and follow-up and compared histological findings among the different groups.

RESULTS: We identified 46 MPO-ANCA-positive, 10 double-positive, and 13 anti-GBM-positive patients. Mean ages were 63, 64, and 52 years (P = 0.04), and serum creatinine levels were 5.0, 10.3, and 9.6 mg/dL (445, 910, and 850 micromol/L), respectively (P = 0.01). Granulomatous periglomerular inflammation was found in either MPO-ANCA- or double-positive patients, but not in anti-GBM-positive patients with CGN without MPO-ANCAs. Patient survival among the 3 groups was different, although not statistically significant (log rank P = 0.17, with 75%, 79%, and 100% alive at 1 year, respectively). Renal survival analysis showed significant differences among the 3 groups (P = 0.04, with 65%, 10%, and 15% off dialysis therapy at 1 year, respectively).

CONCLUSION: In patients with both anti-GBM antibodies and MPO-ANCAs, histological findings differ from those of patients with anti-GBM antibodies only. However, renal survival in these patients is not better than that in anti-GBM-positive patients and is worse compared with patients with MPO-ANCAs only.