title: Early-childhood membranous nephropathy due to cationic bovine serum albumin.
abstract: BACKGROUND
  The M-type phospholipase A(2) receptor (PLA(2)R) was recently identified as a candidate antigen in 70% of cases of idiopathic membranous nephropathy, a common form of the nephrotic syndrome. The nature of antigens involved in other idiopathic and secondary membranous nephropathies remains unclear.
  
  
  METHODS
  We searched for antibodies against bovine serum albumin and circulating bovine serum albumin by means of enzyme-linked immunosorbent assay and Western blotting in serum specimens obtained from 50 patients with membranous nephropathy and 172 controls. The properties of immunopurified circulating bovine serum albumin obtained from serum specimens were analyzed with the use of two-dimensional sodium dodecyl sulfate-polyacrylamide-gel electrophoresis. We detected bovine serum albumin in glomerular deposits and analyzed the reactivity of eluted IgG.
  
  
  RESULTS
  Eleven patients, including four children, had high levels of circulating anti-bovine serum albumin antibodies, of both the IgG1 and IgG4 subclasses. These patients also had elevated levels of circulating bovine serum albumin, without an increase in circulating immune complex levels. Bovine serum albumin immunopurified from the serum specimens of these four children migrated in the basic range of pH, whereas the bovine serum albumin from adult patients migrated in neutral regions as native bovine serum albumin. Bovine serum albumin was detected in subepithelial immune deposits only in the children with both high levels of cationic circulating bovine serum albumin and bovine serum albumin-specific antibodies, and it colocalized with IgG in the absence of PLA(2)R. IgG eluted from such deposits was specific for bovine serum albumin.
  
  
  CONCLUSIONS
  Some patients with childhood membranous nephropathy have both circulating cationic bovine serum albumin and anti-bovine serum albumin antibodies. Bovine serum albumin is present in immune deposits, suggesting that cationic bovine serum albumin is pathogenic through binding to the anionic glomerular capillary wall and in situ formation of immune complexes, as shown in experimental models.
authors.affiliation: INSERM, Unite Mixte de Recherche Scientifique 702, Université Pierre et Marie Curie, Paris 6, Assistance Publique-Hôpitaux de Paris, Tenon Hospital, Paris, France. hanna.debiec@upmc.fr
authors.forename: Hanna
authors.initials: H
authors.lastname: Debiec
authors.forename: Florence
authors.initials: F
authors.lastname: Lefeu
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Kemper
authors.forename: Patrick
authors.initials: P
authors.lastname: Niaudet
authors.forename: Georges
authors.initials: G
authors.lastname: Deschênes
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Remuzzi
authors.forename: Tim
authors.initials: T
authors.lastname: Ulinski
authors.forename: Pierre
authors.initials: P
authors.lastname: Ronco
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002412:Cations; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D015433:Glomerulonephritis, Membranous / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008892:Milk / Q000276:immunology; D012710:Serum Albumin, Bovine / Q000009:adverse effects / Q000032:analysis / Q000276:immunology*
chemical_list: D002412:Cations; D007074:Immunoglobulin G; D012710:Serum Albumin, Bovine