RESUMO
BACKGROUND: Anti-neutrophil cytoplasmic antibodies (ANCA) are classified into perinuclear (P)-ANCA and cytoplasmic-ANCA by an indirect immunofluorescence (IIF) test with ethanol-fixed neutrophils. Circulating P-ANCA with specificity for myeloperoxidase (MPO) are frequently found in patients with pauci-immune necrotizing glomerulonephritis. P-ANCA without a specificity for MPO are also found in a minority of patients with this form of glomerulonephritis, but their clinicopathological features remain poorly delineated. METHODS: The clinical data, the renal pathology, and the outcome were compared between 48 patients with MPO-specific P-ANCA-associated glomerulonephritis (MPO-specific group) and five patients with MPO-nonspecific P-ANCA-associated glomerulonephritis (MPO-nonspecific group). In the MPO-nonspecific group, antibodies against bactericidal/permeability-increasing protein were detected in one patient, but the other known antibodies that can produce a P-ANCA pattern on the IIF test were not detected in the remaining patients. All patients in the two groups were treated with steroids with or without cyclophosphamide. RESULTS: There were no remarkable differences in the degree of hematuria and serum levels of C-reactive protein and creatinine between the two groups. In contrast, proteinuria levels and the rate of glomerular crescent formation were higher in the MPO-nonspecific group than in the MPO-specific group. While the patient survival rate was similar between the two groups, the renal survival rate was lower in the MPO-nonspecific group. CONCLUSIONS: This pilot analysis suggests that there are clinicopathological differences between patients with MPO-specific and -nonspecific P-ANCA-associated pauci-immune necrotizing glomerulonephritis. Renal lesions appear to be more active in patients with MPO-nonspecific P-ANCA than in patients with MPO-specific P-ANCA.
