title: Identification of a novel myositis-associated antibody directed against cortactin.
abstract: OBJECTIVE
  The aim of this study is to describe a novel myositis-associated autoantibody (anti-cortactin antibody) and assess related clinical and immunological manifestations and its clinical significance.
  
  
  METHODS
  Adult patients with myositis (dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and inclusion body myositis), as well as patients with other autoimmune diseases and non-inflammatory myopathies were analyzed for the presence of anti-cortactin antibody using in-house developed ELISA and immunoblotting techniques with a commercial source of purified cortactin. The cut-off for positive status was determined in a group of healthy volunteers.
  
  
  RESULTS
  Antibody against cortactin was positive in 7/34 (20%) polymyositis patients, 9/117 (7.6%) dermatomyositis, 2/7 (26%) immune-mediated necrotizing myopathy, and none of the 4 patients with inclusion body myositis. The antibody also tested positive in 3/101 patients with other autoimmune diseases (2 systemic sclerosis and 1 systemic lupus erythematosus), and in 1/29 patients with non-inflammatory myopathy. No relevant association with specific clinical features was found in patients with these antibodies. Anti-cortactin antibody was more frequently positive in patients with polymyositis and immune-mediated necrotizing myopathy than in the remaining myositis patients, and was the only myositis autoantibody found in sera of 3 patients from these groups.
  
  
  CONCLUSIONS
  Our data indicate that cortactin is a novel target antigen in patients with autoimmune diseases, especially patients with polymyositis or immune-mediated necrotizing myopathy. Anti-cortactin can be considered a new myositis-associated antibody.
authors.affiliation: Internal Medicine Department, Vall d'Hebron General Hospital, Universitat Autonoma de Barcelona, Barcelona, Spain. Electronic address: mlabrador@vhebron.net.
authors.forename: Moisés
authors.initials: M
authors.lastname: Labrador-Horrillo
authors.affiliation: Immunology Department, Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Martínez
authors.affiliation: Internal Medicine Department, Vall d'Hebron General Hospital, Universitat Autonoma de Barcelona, Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Selva-O'Callaghan
authors.affiliation: Internal Medicine Department, Vall d'Hebron General Hospital, Universitat Autonoma de Barcelona, Barcelona, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Trallero-Araguás
authors.affiliation: Muscle Research Unit, Internal Medicine Service, Hospital Clínic de Barcelona, Universitat de Barcelona, Fundación Cellex, Barcelona, Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Grau-Junyent
authors.affiliation: Internal Medicine Department, Vall d'Hebron General Hospital, Universitat Autonoma de Barcelona, Barcelona, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Vilardell-Tarrés
authors.affiliation: Immunology Department, Hospital de la Santa Creu i Sant Pau, Universitat Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Candido
authors.initials: C
authors.lastname: Juarez
mesh_terms: D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology; D051356:Cortactin / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D009220:Myositis / Q000276:immunology*
chemical_list: D001323:Autoantibodies; C495868:CTTN protein, human; D051356:Cortactin
keywords: Anti-CTTN antibody; Cortactin; MAA; Myositis-associated autoantibody