title: Myositis in mixed connective tissue disease: a unique syndrome characterized by immunohistopathologic elements of both polymyositis and dermatomyositis.
abstract: OBJECTIVE
  To characterize the inflammatory cells, the expression pattern of adhesion molecules (ICAM-1 and VCAM-1), membrane attack complex (C5b-9), and major histocompatibility complex (MHC) antigens in muscle biopsy of mixed connective tissue disease (MCTD).
  
  
  METHODS
  We studied 14 patients with MCTD, and compared to 8 polimyositis (PM) patients, 5 dermatomyositis (DM) and 4 dystrophies. Inflammatory cells were examined for CD4+, CD8+, memory and naive T cells, natural killer cells, and macrophages. Expression of MHC-I and -II, ICAM-1, VCAM-1 and C5b -9 were characterized on muscle fibers and vessels.
  
  
  RESULTS
  Morphological analysis displayed a pattern of PM. Immunohistochemical study revealed a decreased number of capillaries, predominance of CD4+ and B cells in perivascular regions and predominance of CD8+ and CD45RO+ in endomysial regions. The expression of MHC-I on vessels and on degenerated muscle fibers, MHC-II expression on vessels and perifascicular muscle fibers, and the expression of ICAM-1 / VCAM-1 on endothelial cells indicated both vascular and cellular-immune mediated processes causing the muscular lesion.
  
  
  CONCLUSIONS
  Our findings revealed a mixed mechanism in MCTD, both vascular involvement as DM, and cell-mediated like PM.
authors.affiliation: Division of Rheumatology, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Maria Angela A G
authors.initials: MA
authors.lastname: Vianna
authors.forename: Claudia T L
authors.initials: CT
authors.lastname: Borges
authors.forename: Eduardo F
authors.initials: EF
authors.lastname: Borba
authors.forename: Maria Teresa C
authors.initials: MT
authors.lastname: Caleiro
authors.forename: Eloisa
authors.initials: E
authors.lastname: Bonfá
authors.forename: Suely K N
authors.initials: SK
authors.lastname: Marie
mesh_terms: D000328:Adult; D017677:Age Distribution; D015703:Antigens, CD / Q000276:immunology; D001323:Autoantibodies / Q000097:blood; D016516:CD4-CD8 Ratio; D015938:Complement Membrane Attack Complex / Q000276:immunology; D003882:Dermatomyositis / Q000276:immunology / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology*; D008285:Major Histocompatibility Complex / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008947:Mixed Connective Tissue Disease / Q000276:immunology / Q000473:pathology; D011287:Prejudice; D011446:Prospective Studies; D019010:Vascular Cell Adhesion Molecule-1 / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D001323:Autoantibodies; D015938:Complement Membrane Attack Complex; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1