title: A New Immunodot Assay for Multiplex Detection of Autoantibodies in a Cohort of Italian Patients With Idiopathic Inflammatory Myopathies.
abstract: BACKGROUND
  Autoantibody detection has been assessed as tool for the diagnosis and the definition of idiopathic inflammatory myopathies (IIM). The aim of the study was to characterize the autoantibody profiling of a cohort of Italian patients with IIM.
  
  
  METHODS
  Sera of 53 adult patients with definite IIM, according to Bohan-Peter criteria, were tested for anti-nuclear autoantibodies (ANA), using indirect immunofluorescence (IIF) method, and for myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs), using two new commercial immunodot assays.
  
  
  RESULTS
  MSAs and/or MAAs were detected in 29 of 53 (54.7%) patients with IIM. Twenty-three patients (43.4%) were positive for at least one MSAs: 13 (24.5%) had anti-histidyl-tRNA synthetase autoantibodies (Jo1), 4 (7.5%) had other anti-aminoacyl-tRNA synthetases autoantibodies (anti-ARS), 1 (1.8%) had anti-transcription intermediary factor 1 gamma autoantibodies (anti-TIF1γ), 2 (3.7%) had anti-nuclear helicase protein Mi-2 autoantibodies (anti-Mi-2), 4 (7.5%) had anti-small ubiquitin like modifier activating enzyme heterodimer autoantibodies (anti-SAE). Moreover, 17 patients (32%) were positive for at least one MAAs. Coexisting MSAs and MAAs were observed in 9 of 53 (16.9%) patients, anti-Jo1/SS-A autoantibodies in most cases. Overall sensitivity of immunodot assays was 54.7%, the specificity was almost absolute. At cut-off value of 1:160, the sensitivity of ANA-IIF was 52.8%, increasing to 66% if cytoplasmatic fluorescence reaction was reported. Notably, two (5.7%) ANA-IIF negative patients had MSAs, detected only by immunodot assays.
  
  
  CONCLUSIONS
  It was possible to identify MSAs otherwise undetectable because of the use of new assays. Immunodot can reveal MSAs even when IIF results are inconclusive or, in some cases, ANA negative.
authors.affiliation: Laboratory of Clinical Pathology, University Hospital of Bari, Bari, Italy. mtampoia@libero.it.
authors.forename: Marilina
authors.initials: M
authors.lastname: Tampoia
authors.affiliation: Interdisciplinary Department of Medicine, Rheumatology Unit, University Hospital of Bari, Bari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Notarnicola
authors.affiliation: Laboratory of Clinical Pathology, University Hospital of Bari, Bari, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Abbracciavento
authors.affiliation: Laboratory of Clinical Pathology, University Hospital of Bari, Bari, Italy.
authors.forename: Antonietta
authors.initials: A
authors.lastname: Fontana
authors.affiliation: Interdisciplinary Department of Medicine, Rheumatology Unit, University Hospital of Bari, Bari, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Giannini
authors.affiliation: Laboratoire Luxembougeois d'Immuno-Pathologie, Esch/Alzette, Luxembourg.
authors.forename: Renè
authors.initials: R
authors.lastname: Louis Humbel
authors.affiliation: Interdisciplinary Department of Medicine, Rheumatology Unit, University Hospital of Bari, Bari, Italy.
authors.forename: Florenzo
authors.initials: F
authors.lastname: Iannone
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000604:Amino Acyl-tRNA Synthetases / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006643:Histidine-tRNA Ligase / Q000276:immunology; D006801:Humans; D007159:Immunologic Tests / Q000379:methods*; D007558:Italy; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000097:blood* / Q000175:diagnosis / Q000276:immunology*; D009687:Nuclear Proteins / Q000276:immunology*; D012698:Serologic Tests
chemical_list: D001323:Autoantibodies; D009687:Nuclear Proteins; D000604:Amino Acyl-tRNA Synthetases; D006643:Histidine-tRNA Ligase
keywords: idiopathic inflammatory myopathies; indirect immunofluorescence method; multiplex assays; myositis-associated autoantibodies; myositis-specific autoantibodies