title: Clinical implications of autoantibody screening in patients with autoimmune myositis.
abstract: OBJECTIVE
  To evaluate the clinical usefulness of serum autoantibody profiling in patients with autoimmune myositis.
  
  
  METHODS
  We retrospectively studied 74 consecutive patients: 68 had definite or probable myositis according to Bohan-Peter criteria, six suffered from antisynthetase syndrome with subclinical myopathy. Myositis specific antibodies (MSA) (anti-ARS, -SRP, -Mi-2) were determined by RNA immunoprecipitation or immunoblot, myositis associated antibodies (MAA) (anti-RoRNP, -U1RNP, -PM/Scl, -Ku) by immunoblot.
  
  
  RESULTS
  Forty-three patients (58%) were positive for MSA: anti-Jo-1 in 15/27 polymyositis (PM) (55%), 4/33 dermatomyositis (DM) (12%), 1/8 overlap (12%) and 2/6 antisynthetase syndrome (33%); anti-ARS non-Jo-1 in 1/27 PM (4%), 2/33 DM (6%) and 4/6 antisynthetase syndrome (67%); anti-Mi-2 in 1/27 PM (4%) and 11/33 DM (33%); anti-SRP in 3/27 PM (11%) and 1/33 DM (3%). One patient was anti-Jo-1/Mi-2 positive, one anti-Jo-1/SRP positive. Moreover, 27 patients (36%) were positive for MAA: anti-Ro/SSA in 8/27 PM (30%), 7/33 DM (21%), 1/8 overlap (12%), and 3/6 antisynthetase syndrome (50%); anti-U1RNP in 1/27 PM (3.7%), 1/33 DM (3%), and 2/8 overlap (25%); anti-PM/Scl in 2/8 overlap (25%), anti-Ku in 2/8 overlap (25%). Anti-Jo-1 was predominantly associated with PM, anti-Mi-2 was almost exclusively found in DM patients. Anti-ARS antibodies were closely associated with interstitial lung disease and polyarthritis; notably, anti-ARS non-Jo-1 was more frequent in patients without overt muscle alterations. Anti-Ro/SSA antibody was not associated with any disease subset, but significantly more frequent in antisynthetase syndrome.
  
  
  CONCLUSIONS
  Searching for MSA and MAA in patients with autoimmmune myositis is recommended because of its diagnostic and clinical value. Anti-ARS non-Jo-1 antibodies seem to preferentially target patients with pulmonary fibrosis without overt myopathy.
authors.affiliation: University of Padova, Division of Rheumatology, Department of Clinical and Experimental Medicine, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Ghirardello
authors.forename: S
authors.initials: S
authors.lastname: Zampieri
authors.forename: E
authors.initials: E
authors.lastname: Tarricone
authors.forename: L
authors.initials: L
authors.lastname: Iaccarino
authors.forename: R
authors.initials: R
authors.lastname: Bendo
authors.forename: C
authors.initials: C
authors.lastname: Briani
authors.forename: R
authors.initials: R
authors.lastname: Rondinone
authors.forename: P
authors.initials: P
authors.lastname: Sarzi-Puttini
authors.forename: S
authors.initials: S
authors.lastname: Todesco
authors.forename: A
authors.initials: A
authors.lastname: Doria
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000974:Antibodies, Antinuclear / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000276:immunology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000175:diagnosis* / Q000276:immunology; D012189:Retrospective Studies
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies