title: Development of a standardized ELISA for the determination of autoantibodies against human M-type phospholipase A2 receptor in primary membranous nephropathy.
abstract: BACKGROUND
  Autoantibodies against the M-type phospholipase A2 receptor (PLA2R1) are specific markers for primary membranous nephropathy (pMN) and anti-PLA2R1 serum levels may be useful to monitor disease activity. So far, a recombinant cell-based indirect immunofluorescence assay (RC-IFA) using recombinant PLA2R1 as a substrate has been widely available but lacks a finely graduated assessment of antibody concentrations.
  
  
  METHODS
  In order to setup a standardized ELISA, the extracellular domain of human PLA2R1 was expressed in HEK293. The purified protein was used to form the solid-phase in an ELISA which was then employed to analyze sera from 200 patients with primary MN, 27 patients with secondary MN, 230 patients with other glomerular diseases, 316 patients with systemic autoimmune diseases, and from 291 healthy blood donors.
  
  
  RESULTS
  At a set specificity of 99.9% the sensitivity of the anti-PLA2R1 IgG ELISA was found to be 96.5%. A similar sensitivity (98.5%) was obtained when binding of only subclass IgG4 was analyzed. The calibrated assay showed a good class correlation with the results of the RC-IFA, was robust and could be stored for several months without any loss of quality.
  
  
  CONCLUSIONS
  The results demonstrate that the new test system is qualified for routine use and that it has an almost perfect agreement with both, the clinical characterization of the patients and the results generated with RC-IFA.
authors.affiliation: EUROIMMUN AG, Lübeck, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Dähnrich
authors.forename: Lars
authors.initials: L
authors.lastname: Komorowski
authors.forename: Christian
authors.initials: C
authors.lastname: Probst
authors.forename: Barbara
authors.initials: B
authors.lastname: Seitz-Polski
authors.forename: Vincent
authors.initials: V
authors.lastname: Esnault
authors.forename: Jack F
authors.initials: JF
authors.lastname: Wetzels
authors.forename: Julia M
authors.initials: JM
authors.lastname: Hofstra
authors.forename: Elion
authors.initials: E
authors.lastname: Hoxha
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Stahl
authors.forename: Gérard
authors.initials: G
authors.lastname: Lambeau
authors.forename: Winfried
authors.initials: W
authors.lastname: Stöcker
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schlumberger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D005260:Female; D015870:Gene Expression; D015433:Glomerulonephritis, Membranous / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017434:Protein Structure, Tertiary; D054507:Receptors, Phospholipase A2 / Q000097:blood* / Q000737:chemistry / Q000276:immunology; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D054507:Receptors, Phospholipase A2