title: Deposition of the lectin pathway of complement in renal biopsies of lupus nephritis patients.
abstract: OBJECTIVE
  Lupus nephritis (LN) is one of the most serious manifestations of SLE occurring in 66-90% of these patients. The complement system is part of the innate immunity and modulator of inflammation and the adaptative immune response. Mannan-binding lectin (MBL) and Ficolin-2 (FCN-2) are important members of the lectin pathway of complement activation. Despite the significant participation of complement in the pathogenesis of the LN, there are few reports demonstrating "in situ" deposition of complement components in renal biopsy specimens in this disorder. The present study investigated the deposition of complement components in kidney specimens of LN patients.
  
  
  METHODS
  Renal biopsies of 11 patients with SLE and LN were evaluated for immunofluorescence staining for IgG, IgA, IgM, C3, and C1q. Additionally, MBL, FCN-2 and C5b-9 were researched using monoclonal antibodies.
  
  
  RESULTS
  All the biopsies were positive for IgG, C3, and C1q, eight were positive IgM and five had IgA deposition in glomerular tissue. The terminal complex of complement C5b9 was positive in all cases, MBL in nine (82%) cases; seven (63.6%) of them presenting concomitantly FCN-2 deposition. Patients presenting MBL deposition had higher mean of urinary proteins (9.0 g/day) than patients with negative MBL deposition (mean of 2.3g/day).
  
  
  CONCLUSIONS
  In this study, we demonstrated in situ the participation of complement in the renal injury, including MBL and FCN-2 of the lectin pathway; also the strong role of C5b-9 in the pathogenesis of LN.
authors: Laboratory of Molecular Immunopathology and Department of Medical Pathology, Federal University of Paraná, Curitiba, Brazil.
authors: Renato M
authors: RM
authors: Nisihara
authors: Fernanda
authors: F
authors: Magrini
authors: Valmir
authors: V
authors: Mocelin
authors: Iara J
authors: IJ
authors: Messias-Reason
mesh_terms: D000328:Adult; D000936:Antigen-Antibody Complex / Q000276:immunology / Q000378:metabolism; D001706:Biopsy; D037582:Complement Pathway, Mannose-Binding Lectin / Q000276:immunology*; D003165:Complement System Proteins / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D007132:Immunoglobulin Isotypes / Q000276:immunology / Q000378:metabolism; D007668:Kidney / Q000276:immunology / Q000473:pathology; D007678:Kidney Glomerulus / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008181:Lupus Nephritis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008856:Microscopy, Fluorescence; D055815:Young Adult
chemical_list: D000936:Antigen-Antibody Complex; D007132:Immunoglobulin Isotypes; D003165:Complement System Proteins