title: Comparison of radioimmunoprecipitation versus antigen-specific assays for identification of myositis-specific autoantibodies in dermatomyositis patients.
abstract: BACKGROUND
  To confirm the antigen specificities of autoantibodies that precipitate 140-kDa (anti-p140) or 155/140-kDa polypeptides (anti-p155/140) previously identified by radioimmunoprecipitation in Korean patients with dermatomyositis (DM) and to look into the relationship between each MSA and clinical features of DM.
  
  
  METHODS
  Seventeen serum samples of classic DM patients who had been found to have either anti-p140 antibodies (n = 9) or anti-p155/140 (n = 8) antibodies in our previous study were examined using enzyme-linked immunosorbent assay (for anti-MDA5 antibodies) and immunoblotting (for anti-MJ/NXP-2 and anti-TIF-1γ antibodies).
  
  
  RESULTS
  Seven out of nine anti-p140 antibody positive patients were found to have anti-MDA5 antibodies. Two out of nine had anti-MJ/NXP-2 antibodies with no interstitial lung disease (ILD). All eight anti-p155/140 antibody positive patients were found to have anti-TIF-1γ antibodies. Anti-TIF-1γ and anti-MDA5 antibodies were simultaneously detected in one patient with anti-p155/140 antibody, who suffered HIV infection and non-Hodgkin's lymphoma. The associations between anti-MDA5 antibody and rapidly progressive ILD and between anti-TIF-1γ antibody and cancer-associated DM were confirmed to be significant.
  
  
  CONCLUSIONS
  Although radioimmunoprecipitation still looks to be a good screening tool, confirmation with antigen-specific assays seems mandatory. The associations between anti-MDA5 and rapidly progressive ILD and between anti-TIF-1γ and cancer-associated DM were confirmed in Korean patients with DM.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Seoul National University Bundang Hospital , Seongnam , Republic of Korea.
authors.forename: Eun Ha
authors.initials: EH
authors.lastname: Kang
authors.forename: Masataka
authors.initials: M
authors.lastname: Kuwana
authors.forename: Yuka
authors.initials: Y
authors.lastname: Okazaki
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Lee
authors.forename: Yun Jong
authors.initials: YJ
authors.lastname: Lee
authors.forename: Eun Bong
authors.initials: EB
authors.lastname: Lee
authors.forename: Yeong Wook
authors.initials: YW
authors.lastname: Song
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000032:analysis*; D015153:Blotting, Western; D003882:Dermatomyositis / Q000175:diagnosis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015531:Radioimmunoprecipitation Assay; D055815:Young Adult
chemical_list: D001323:Autoantibodies
keywords: antibody specificities; autoantibodies; myositis