title: Diagnostic value and clinical laboratory associations of antibodies against recombinant ribosomal P0, P1 and P2 proteins and their native heterocomplex in a Caucasian cohort with systemic lupus erythematosus.
abstract: BACKGROUND
  In this study, we sought to determine the diagnostic value and clinical laboratory associations of autoantibodies against recombinant ribosomal P0, P1 and P2 proteins and their native heterocomplex in systemic lupus erythematosus (SLE).
  
  
  METHODS
  Autoantibodies against recombinant ribosomal P proteins (aRibPR0, aRibPR1 and aRibPR2) and antibodies against native ribosomal P heterocomplex (aRibPNH) were determined in sera from patients with SLE (n = 163), systemic sclerosis (n = 66), Sjögren's syndrome (n = 54), rheumatoid arthritis (n = 90) and healthy donors (n = 100) using enzyme-linked immunosorbent assay. Test results were correlated to medical records, including the American College of Rheumatology criteria, the Systemic Lupus Erythematosus Disease Activity Index 2000, laboratory data and medications of all SLE patients.
  
  
  RESULTS
  Sensitivities of 22.0% for aRibPR0, 14.9% for aRibPR2, 14.3% for aRibPNH and 10.7% for aRibPR1 were obtained at a specificity of 99%. The assay for aRibPR0 detection demonstrated the best performance in receiver-operating characteristics analysis, with aRibPR0 detectable in 10% of anti-Smith antibody and anti-double-stranded DNA-negative sera at a specificity of 100%. ARibPR0 positivity was associated with lymphocytopenia. ARibPR1+ patients had significantly higher γ-glutamyl transpeptidase (GGT) levels than their aRibPR1- counterparts. No specific damage occurred in aRibP+ lupus patients compared with a group of age-, sex- and nephritis-matched aRibP- lupus patients within 3 years.
  
  
  CONCLUSIONS
  The determination of antibodies against ribosomal P proteins improves the diagnosis of SLE and should therefore be implemented in upcoming criteria for the diagnosis or classification of SLE. High titers of aRibPR0 can be associated with lymphocytopenia, and high titers of aRibPR1 can be associated with elevated GGT levels. So far, there is no evidence for a prognostic value of aRibPs for damage.
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin Berlin, Chariteplatz 1, Berlin D-10117, Germany.
authors.forename: Fidan
authors.initials: F
authors.lastname: Barkhudarova
authors.forename: Cornelia
authors.initials: C
authors.lastname: Dähnrich
authors.forename: Anke
authors.initials: A
authors.lastname: Rosemann
authors.forename: Udo
authors.initials: U
authors.lastname: Schneider
authors.forename: Winfried
authors.initials: W
authors.lastname: Stöcker
authors.forename: Gerd-Rüdiger
authors.initials: GR
authors.lastname: Burmester
authors.forename: Karl
authors.initials: K
authors.lastname: Egerer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schlumberger
authors.forename: Falk
authors.initials: F
authors.lastname: Hiepe
authors.forename: Robert
authors.initials: R
authors.lastname: Biesen
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens / Q000276:immunology; D015415:Biomarkers / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D010750:Phosphoproteins / Q000276:immunology*; D012269:Ribosomal Proteins / Q000276:immunology*; D012680:Sensitivity and Specificity; D044465:White People; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; D010750:Phosphoproteins; D012269:Ribosomal Proteins; C031937:phosphoprotein P2, ribosomal; C035690:ribosomal phosphoprotein P1; C054675:ribosomal protein P0