Renal Neutrophils Infiltration in Antineutrophil Cytoplasmic Antibodies-Negative Pauci-Immune Crescentic Glomerulonephritis

Introduction: This study aims to investigate the evidence of neutrophil infiltration in renal tissue from patients with antineutrophil cytoplasmic antibodies (ANCA)-negative pauci-immune crescentic glomerulonephritis (CrGN), and a comparison with their ANCA-positive counterparts was performed. Methods: Renal biopsy specimens from 31 patients with pauci-immune CrGN were collected. Twelve patients were ANCA negative, and 19 patients were ANCA positive. Neutrophil infiltration was investigated by staining of 2 markers, CD15 and myeloperoxidase (MPO), using immunohistochemistry. Results: Positive-stained cells of CD15 (CD15(+)) and MPO (MPO+) were mainly located in glomeruli with cellular crescents and segmental fibrinoid necrotic lesions and in periglomerular area of cellular crescents, especially at the area of ruptured Bowman capsule. Scanty positive staining was found in normal renal tissue. The number of CD15(+) cells in the glomeruli and periglomerular area was significantly higher in ANCA-negative group than in ANCA-positive group (in glomeruli: 2.70 +/- 1.61 versus 1.38 +/- 0.85, P = 0.019; in periglomerular area: 4.35 +/- 4.36 versus 1.48 +/- 1.67, P = 0.047). The number of MPO+ cells in the periglomerular area was also significantly higher in ANCA-negative group than that in ANCA-positive group. Conclusions: Renal neutrophil infiltration might play a pathogenic role in ANCA-negative pauci-immune CrGN, and the neutrophil infiltration might be more severe in ANCA-negative pauci-immune CrGN than in ANCA-positive one.