title: [MHC class I antigens, CD4 and CD8 expressions in polymyositis and dermatomyositis].
abstract: OBJECTIVE
  To analyze the frequencies of the expression of major histocompatibility complex class I (MHC-I) antigens, and CD4 and CD8 cells in skeletal muscle in polymyositis (PM) and dermatomyositis (DM).
  
  
  METHODS
  This was a retrospective study of 34 PM cases, 8 DM cases, and 29 control patients with non-inflammatory myopathies.
  
  
  RESULTS
  MHC-I antigens were expressed in the sarcolemma and/or sarcoplasm in 79.4% of PM cases, 62.5% of DM cases, and 27.6% of controls (CD4 expression was observed in 76.5%, 75%, and 13.8%, respectively). There was a high suspicion of PM/DM (mainly PM) in patients in whom MHC-I antigens and CD4 were co-expressed. In 14.3% of PM/DM cases, we observed MHC-I antigens expression alone, without inflammatory cells.
  
  
  CONCLUSIONS
  MCH-I antigens expression and CD4 positivity might add to strong diagnostic suspicion of PM/DM. No cellular infiltration was observed in 14.3% of such cases.
authors.affiliation: Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, SP, Brasil. Electronic address: cgraca@hotmail.com.
authors.forename: Carla Renata
authors.initials: CR
authors.lastname: Graça
authors.affiliation: Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, SP, Brasil.
authors.forename: João Aris
authors.initials: JA
authors.lastname: Kouyoumdjian
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015704:CD4 Antigens / Q000032:analysis / Q000096:biosynthesis*; D016827:CD8 Antigens / Q000032:analysis / Q000096:biosynthesis*; D002648:Child; D003882:Dermatomyositis / Q000276:immunology / Q000378:metabolism*; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000032:analysis / Q000096:biosynthesis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000737:chemistry; D017285:Polymyositis / Q000276:immunology / Q000378:metabolism*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I
keywords: Antígenos de complexo principal de histocompatibilidade classe I (MHC‐I); Biópsia muscular; Imuno‐histoquímica muscular; Inflammatory myopathies; Major histocompatibility complex class I antigens (MHC‐I); Miopatias inflamatórias; Muscle biopsy; Muscle immunohistochemistry; Muscle pathology; Patologia muscular