title: Autoantibodies to transcription intermediary factor TIF1β associated with dermatomyositis.
abstract: BACKGROUND
  Myositis specific autoantibodies are associated with unique clinical subsets and are useful biomarkers in polymyositis/dermatomyositis (PM/DM). A 120 kD protein recognized by certain patients with DM was identified and clinical features of patients with this specificity were characterized.
  
  
  METHODS
  The 120 kD protein recognized by a prototype serum was purified and identified by mass spectrometry and immunological methods. Autoantibody to this 120 kD protein was screened in sera from 2,356 patients with various diagnoses from four countries, including 254 PM/DM, by immunoprecipitation of 35S-methionine labeled K562 cell extracts. Clinical information of patients with this specificity was collected.
  
  
  RESULTS
  The 120 kD protein, which exactly comigrated with PL-12, was identified as transcription intermediary factor TIF1β (TRIM28) by mass spectrometry and validated by immunoassays. By immunofluorescence, anti-TIF1β positivity showed a fine-speckled nuclear staining pattern. Four cases of anti-TIF1β were identified; all are women, one each in a Japanese, African American, Caucasian, and Mexican individual. Three had a diagnosis of DM and one case was classified as having an undifferentiated connective tissue disease with an elevated CPK but without significant muscle symptoms. This individual also had a history of colon cancer, cervical squamous metaplasia and fibroid tumors of the uterus. Myopathy was mild in all cases and resolved without treatment in one case. The anti-TIF1β specificity was not found in other conditions.
  
  
  CONCLUSIONS
  Anti-TIF1β is a new DM autoantibody associated with a mild form of myopathy. Whether it has an association with malignancy, as in the case of anti-TIF1γ, or other unique features will need to be evaluated in future studies.
authors.affiliation: Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Florida, P,O,Box 100221, 1600 SW Archer Rd, Gainesville, FL 32610-0221, USA. minoru.satoh@medicine.ufl.edu
authors.forename: Minoru
authors.initials: M
authors.lastname: Satoh
authors.forename: Jason Y F
authors.initials: JY
authors.lastname: Chan
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ross
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Yoshioki
authors.initials: Y
authors.lastname: Yamasaki
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Yamada
authors.forename: Monica
authors.initials: M
authors.lastname: Vazquez-del Mercado
authors.forename: Marcelo H
authors.initials: MH
authors.lastname: Petri
authors.forename: Luis J
authors.initials: LJ
authors.lastname: Jara
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Saavedra
authors.forename: Claudia
authors.initials: C
authors.lastname: Cruz-Reyes
authors.forename: Eric S
authors.initials: ES
authors.lastname: Sobel
authors.forename: Westley H
authors.initials: WH
authors.lastname: Reeves
authors.forename: Angela
authors.initials: A
authors.lastname: Ceribelli
authors.forename: Edward K L
authors.initials: EK
authors.lastname: Chan
mesh_terms: D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000096:biosynthesis*; D015415:Biomarkers / Q000097:blood; D003882:Dermatomyositis / Q000175:diagnosis* / Q000276:immunology*; D005260:Female; D006801:Humans; D020014:K562 Cells; D008969:Molecular Sequence Data; D009135:Muscular Diseases / Q000175:diagnosis / Q000276:immunology; D012042:Registries; D012097:Repressor Proteins / Q000276:immunology*; D000076183:Tripartite Motif-Containing Protein 28
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D012097:Repressor Proteins; C101116:TRIM28 protein, human; D000076183:Tripartite Motif-Containing Protein 28