title: Critical comparative analyses of anti-alpha-actinin and glomerulus-bound antibodies in human and murine lupus nephritis.
abstract: OBJECTIVE
  Although anti-double-stranded DNA (anti-dsDNA) antibodies are important in lupus nephritis, the question regarding which glomerular structures (alpha-actinin, nucleosomes, or others) are recognized by nephritogenic anti-dsDNA antibodies is still controversial. In this study, we determined which glomerular structures are recognized by monoclonal and in vivo-bound nephritogenic antibodies.
  
  
  METHODS
  Western blotting was used to analyze the ability of nephritogenic anti-dsDNA antibodies to recognize glomerular and nucleosomal structures. Sera from patients with lupus nephritis, sera from random antinuclear antibody-positive patients, and paired antibodies from sera and kidney eluates from nephritic (NZB x NZW)F(1) mice were analyzed for activity against proteins identified by monoclonal nephritogenic antibodies, and against alpha-actinin, dsDNA, nucleosomes, histone H1, heparan sulfate, DNase I, and type IV collagen. Immunoelectron microscopy was used to determine the glomerular localization of alpha-actinin and in vivo-bound autoantibodies in nephritic (NZB x NZW)F1 mouse kidneys.
  
  
  RESULTS
  Anti-alpha-actinin antibodies were observed in human and murine lupus nephritis sera and in sera from patients without systemic lupus erythematosus and were not detected in kidney eluates from nephritic mice. Antibodies to dsDNA and histone H1 were detected in all eluates. Western blot analyses revealed that nephritogenic anti-dsDNA antibodies recognized a 32-kd band, identified as histone H1. Competitive enzyme-linked immunosorbent assay demonstrated that nephritogenic monoclonal antibodies, and dominant antibodies eluted from nephritic kidneys, cross-reacted with dsDNA and H1. This cross-reactive anti-H1 specificity was largely absent in sera from those mice. Immunoelectron microscopic analysis of nephritic (NZB x NZW)F1 mouse kidneys revealed that antibodies eluted from kidneys, but not anti-alpha-actinin antibodies, bound to distinct nephritis-associated electron-dense structures linked to glomerular basement membranes.
  
  
  CONCLUSIONS
  Cross-reactive anti-dsDNA/anti-histone H1 antibodies, but not anti-alpha-actinin antibodies, are central among those deposited in nephritic glomeruli.
authors.affiliation: University of Tromsø, Tromso, Norway.
authors.forename: Manar
authors.initials: M
authors.lastname: Kalaaji
authors.forename: Gunnar
authors.initials: G
authors.lastname: Sturfelt
authors.forename: Janne Erikke
authors.initials: JE
authors.lastname: Mjelle
authors.forename: Hans
authors.initials: H
authors.lastname: Nossent
authors.forename: Ole Petter
authors.initials: OP
authors.lastname: Rekvig
mesh_terms: D000185:Actinin / Q000276:immunology*; D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001323:Autoantibodies / Q000032:analysis*; D001485:Basement Membrane / Q000276:immunology; D015153:Blotting, Western; D003429:Cross Reactions; D004247:DNA / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006657:Histones / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D007678:Kidney Glomerulus / Q000276:immunology*; D008181:Lupus Nephritis / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008814:Mice, Inbred NZB; D008854:Microscopy, Electron; D008875:Middle Aged
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D006657:Histones; D000185:Actinin; D004247:DNA