title: A case of C3 glomerulonephritis successfully treated with eculizumab.
abstract: BACKGROUND
  C3 glomerulonephritis (C3GN) is a rare form of glomerulopathy that is characterized by predominant C3 deposits. Eculizumab, a humanized monoclonal C5 antibody, has recently emerged as a treatment option for C3GN. We report a C3GN patient successfully treated with eculizumab.
  
  
  METHODS
  A 5-year-old boy who presented with proteinuria, hematuria, high ASO titers, and low C3 levels was initially diagnosed with post-streptococcal GN. His first kidney biopsy confirmed this diagnosis, but complement investigations identified three alternative pathway dysregulation factors: C3 nephritic factor, complement factor I heterozygous mutation (I398L), and anti-factor H autoantibodies (4,500 AU/ml). A second biopsy performed 11 months after initial presentation (nephrotic range proteinuria) showed a C3GN suggestive of isolated C3 deposits. Despite the use of intensive immunosuppressive therapy (rituximab, corticosteroids, mycophenolate), nephrotic-range proteinuria persisted and a third kidney biopsy showed the same C3GN pattern with more endocapillary proliferation. The serum C5b-9 level was elevated. Eculizumab was initiated and resulted in a significant decline of proteinuria (5.3 to 1.3 g/day) and an improvement in pathologic features. A transient interruption of eculizumab resulted in a rapid rise in proteinuria to 9.3 g/day, which decreased to 0.8 g/day after resumption of treatment.
  
  
  CONCLUSIONS
  The administration of anti-C5 antibodies may represent a valuable therapeutic option in patients with C3GN.
authors: Department of Pediatrics, Division of Nephrology, CHU Sainte Justine and University of Montreal, 3175 Côte Sainte Catherine, H3T1C5, Montreal, QC, Canada.
authors: Alexis
authors: A
authors: Payette
authors: Natalie
authors: N
authors: Patey
authors: Marie-Agnès
authors: MA
authors: Dragon-Durey
authors: Véronique
authors: V
authors: Frémeaux-Bacchi
authors: Françoise
authors: F
authors: Le Deist
authors: Anne-Laure
authors: AL
authors: Lapeyraque
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D002675:Child, Preschool; D003176:Complement C3 / Q000276:immunology* / Q000378:metabolism; D005921:Glomerulonephritis / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007678:Kidney Glomerulus / Q000187:drug effects* / Q000276:immunology / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D011507:Proteinuria / Q000188:drug therapy / Q000276:immunology; D012074:Remission Induction; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D015415:Biomarkers; C038245:C3 protein, human; D003176:Complement C3; D007166:Immunosuppressive Agents; C481642:eculizumab