Antineutrophil cytoplasmic antibody-associated glomerulonephritis with immunoglobulin deposition.
BACKGROUND
Antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis is commonly classified as pauci-immune glomerulonephritis; however, some cases have granular immunoglobulin deposition along the glomerular capillary. The pathogenesis of immune deposits is poorly studied.


METHODS
Of 66 patients diagnosed with ANCA-associated glomerulonephritis on renal biopsy, cases with immunoglobulin deposition along the glomerular capillary were identified and their clinicopathological characteristics were analyzed. We also performed myeloperoxidase (MPO) and double immunofluorescence (IF) stainings to determine the presence of immune complex antigens.


RESULTS
Granular IgG deposition, IgG plus IgM deposition, and IgM deposition were observed in 15 (22.1%), 8 (11.2%), and 17 (25.0%) cases, respectively. In cases with granular IgG deposition, MPO-IgG double IF staining revealed co-localization of MPO and IgG. In cases with granular IgM deposition, MPO-IgM double IF staining did not co-localize. By electron microscopy, subepithelial deposition as well as intramembranous, subendothelial, and mesangial deposition was detected in the patients with IgG deposition. In addition, renal survival curves were not significantly different between the immunoglobulin deposition and non-deposition groups.


CONCLUSIONS
Granular IgG and/or IgM deposition was observed in 60.6% of patients with ANCA-associated glomerulonephritis. In cases with IgG deposition, electron-dense deposits (EDDs) were observed at various sites in the glomerulus, and MPO and IgG immunocomplex deposition was frequently observed along the glomerular capillary. With IgM deposition, EDDs were not obvious in the glomerular basement membrane, and MPO and IgM immunocomplex was not detected. These data suggest differential mechanism between IgG deposition and IgM deposition.
Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Orie
O
Hirose
Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan. m-itaba@fb4.so-net.ne.jp.
Mitsuyo
M
Itabashi
Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Takashi
T
Takei
Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan.
Kazuho
K
Honda
Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Kosaku
K
Nitta
D000328:Adult; D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D002196:Capillaries / Q000276:immunology / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005455:Fluorescent Antibody Technique; D050533:Glomerular Basement Membrane / Q000276:immunology / Q000473:pathology; D005921:Glomerulonephritis / Q000145:classification / Q000175:diagnosis / Q000276:immunology* / Q000628:therapy; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007075:Immunoglobulin M / Q000032:analysis*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D053208:Kaplan-Meier Estimate; D007678:Kidney Glomerulus / Q000187:drug effects / Q000276:immunology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009195:Peroxidase / Q000032:analysis; D017582:Renal Replacement Therapy; D013997:Time Factors; D016896:Treatment Outcome
D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D005938:Glucocorticoids; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007166:Immunosuppressive Agents; D009195:Peroxidase
ANCA; Histopathology; Immunocomplex; Immunoglobulin; MPO