title: Cytosolic 5'-Nucleotidase 1A As a Target of Circulating Autoantibodies in Autoimmune Diseases.
abstract: OBJECTIVE
  Prior investigations demonstrated that autoantibodies recognizing cytosolic 5'-nucleotidase 1A (NT5C1A) are found in 33-76% of patients with inclusion body myositis (IBM) but are observed only rarely in patients with polymyositis (PM). Thus, anti-NT5C1A may help distinguish IBM from PM. Although 4-21% of patients with dermatomyositis (DM) were shown to be anti-NT5C1A antibody positive, the clinical features of anti-NT5C1A-positive patients with DM have not been described. Furthermore, the prevalence of anti-NT5C1A antibodies in other rheumatic conditions has not been reported. This study was undertaken to define the prevalence and clinical features of anti-NT5C1A-positive patients with DM, PM, IBM, or other systemic autoimmune diseases.
  
  
  METHODS
  We screened for anti-NT5C1A autoantibodies in patients with IBM, DM, PM, Sjögren's syndrome (SS), or systemic lupus erythematosus (SLE) and in healthy volunteers. Clinical characteristics were compared between patients who were anti-NT5C1A positive and those who were anti-NT5C1A negative.
  
  
  RESULTS
  Anti-NT5C1A autoantibodies were detected in 71 (61%) of 117 patients with IBM, 2 (5%) of 42 patients with PM, 2 (5%) of 42 healthy volunteers, 24 (15%) of 159 patients with DM, 10 (23%) of 44 patients with SS, and 13 (14%) of 96 patients with SLE. No anti-NT5C1A antibody-positive patients with SS or SLE had muscle involvement. Anti-NT5C1A-positive patients with IBM had a lower prevalence of rimmed vacuoles (62% versus 83% of antibody-negative patients; P = 0.02). No differences in the clinical characteristics of antibody-positive and antibody-negative patients with DM, SS, or SLE were observed.
  
  
  CONCLUSIONS
  Anti-NT5C1A is a common target of circulating autoantibodies, especially in IBM but also in several different autoimmune diseases. In SLE and SS, anti-NT5C1A autoreactivity is not associated with muscle disease.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Lloyd
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Lisa
authors.initials: L
authors.lastname: Christopher-Stine
authors.affiliation: Vall d'Hebron University Hospital, Barcelona, Spain.
authors.forename: Iago
authors.initials: I
authors.lastname: Pinal-Fernandez
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Eleni
authors.initials: E
authors.lastname: Tiniakou
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Michelle
authors.initials: M
authors.lastname: Petri
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Alan
authors.initials: A
authors.lastname: Baer
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Sonye K
authors.initials: SK
authors.lastname: Danoff
authors.affiliation: National Institute of Arthritis and Musculoskeletal and Skin Diseases/NIH, Bethesda, Maryland.
authors.forename: Katherine
authors.initials: K
authors.lastname: Pak
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Livia A
authors.initials: LA
authors.lastname: Casciola-Rosen
authors.affiliation: National Institute of Arthritis and Musculoskeletal and Skin Diseases/NIH, Bethesda, and Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Mammen
mesh_terms: D015720:5'-Nucleotidase / Q000276:immunology*; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003882:Dermatomyositis / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000276:immunology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012698:Serologic Tests
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D015720:5'-Nucleotidase; C552626:NT5C1A protein, human