title: Reactivity in ELISA with DNA-loaded nucleosomes in patients with proliferative lupus nephritis.
abstract: Autoantibodies against nucleosomes are considered a hallmark of systemic lupus erythematosus (SLE). We compared in patients with proliferative lupus nephritis the diagnostic usefulness of a dsDNA-loaded nucleosome ELISA (anti-dsDNA-NcX) with ELISAs in which dsDNA or nucleosomes alone were coated. First, we analysed whether DNA loading on nucleosomes led to masking of epitopes by using defined monoclonal anti-DNA, anti-histone and nucleosome-specific autoantibodies to evaluate the accessibility of nucleosomal epitopes in the anti-dsDNA-NcX ELISA. Second, autoantibody levels were measured in these 3 ELISAs in 100 patients with proliferative lupus nephritis (LN) before immunosuppressive treatment and in 128 non-SLE disease controls. In patients with LN inter-assay comparisons and associations with clinical and serological parameters were analysed. The panel of monoclonal antibodies revealed that all epitopes were equally accessible in the anti-dsDNA-NcX ELISA as in the two other ELISAs. Patients with proliferative lupus nephritis were positive with dsDNA-loaded nucleosomes in 86%, with DNA in 66% and with nucleosomes in 85%. In the non-lupus disease control group these frequencies were 1.6% (2 out of 128) for both the anti-dsDNA-NcX and the anti-dsDNA ELISA and 0% in the anti-nucleosome ELISA. The levels in the anti-dsDNA-NcX ELISA were high in a group of patients with LN that showed absent reactivity in the anti-DNA or low levels in the anti-nucleosome ELISA. Anti-dsDNA-NcX positivity was associated with higher SLEDAI scores within this group. Within nucleosome-based ELISAs, we propose the anti-dsDNA-NcX ELISA as the preferred test system.
authors.affiliation: Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Dieker
authors.affiliation: Euroimmun, Medizinische Labordiagnostika AG, Lübeck, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schlumberger
authors.affiliation: Royal National Hospital for Rheumatic Diseases, Bath, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: McHugh
authors.affiliation: Royal National Hospital for Rheumatic Diseases, Bath, United Kingdom.
authors.forename: Philip
authors.initials: P
authors.lastname: Hamann
authors.affiliation: Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: van der Vlag
authors.affiliation: Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address: jo.berden@radboudumc.nl.
authors.forename: Jo H
authors.initials: JH
authors.lastname: Berden
mesh_terms: D000293:Adolescent; D000328:Adult; D000974:Antibodies, Antinuclear / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology; D016022:Case-Control Studies; D004247:DNA / Q000737:chemistry / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000706:statistics & numerical data*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005260:Female; D006657:Histones / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D008181:Lupus Nephritis / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009707:Nucleosomes / Q000737:chemistry / Q000276:immunology*
chemical_list: D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D000939:Epitopes; D006657:Histones; D007166:Immunosuppressive Agents; D009707:Nucleosomes; D004247:DNA
keywords: Anti-DNA-loaded nucleosome; Anti-dsDNA; Anti-nucleosome; Lupus; Lupus nephritis