title: Anti-heart and anti-intercalated disk autoantibodies: evidence for autoimmunity in idiopathic recurrent acute pericarditis.
abstract: BACKGROUND
  Idiopathic recurrent acute pericarditis (IRAP) is a rare disease of suspected, yet unproved, immune-mediated origin. The finding of serum heart-specific autoantibodies in IRAP would strengthen the autoimmune hypothesis and provide aetiology-specific non-invasive biomarkers. Objective To assess frequency of serum anti-heart (AHA), anti-intercalated-disk (AIDA) and non-cardiac-specific autoantibodies and their clinical and instrumental correlates in patients with IRAP. Patients 40 consecutive patients with IRAP, 25 male, aged 37+/-16 years, representing a large single-centre cohort collected at a referral centre over a long time period (median 5 years, range 1-22 years). Control groups included patients with non-inflammatory cardiac disease (NICD) (n=160), ischaemic heart failure (n=141) and normal subjects (n=270).
  
  
  METHODS
  AHA (organ-specific, cross-reactive 1 and 2 types) and AIDA were detected in serum samples from patients, at last follow-up, and control subjects by indirect immunofluorescence (IIF) on human myocardium and skeletal muscle. Non-cardiac-specific autoantibodies were detected by IIF, and anti-Ro/SSA, anti-La/SSB by ELISA.
  
  
  RESULTS
  The frequencies of cross-reactive 1 AHA and of AIDA were higher (50%; 25%) in IRAP than in NICD (4%; 4%), ischaemic (1%; 2%) or normal subjects (3%; 0%) (p=0.0001). AHA and/or AIDA were found in 67.5% patients with IRAP. Of the non-cardiac-specific antibodies, only antinuclear autoantibodies at titre > or =1/160 were more common in IRAP (5%) versus normal (0.5%, p<0.04). AIDA in IRAP were associated with a higher number of recurrences (p=0.01) and hospitalisations (p=0.0001), high titre (1/80 or higher) AHA with a higher number of recurrences (p=0.02).
  
  
  CONCLUSIONS
  The detection of AHA and of AIDA supports the involvement of autoimmunity in the majority of patients with IRAP.
authors.affiliation: Division of Cardiology, Department of Cardiological, Thoracic and Vascular Sciences, Centro V Gallucci,University of Padova-Policlinico, Via Giustiniani, 2, Padova 35128, Italy. alida.caforio@unipd.it
authors.forename: A L P
authors.initials: AL
authors.lastname: Caforio
authors.forename: A
authors.initials: A
authors.lastname: Brucato
authors.forename: A
authors.initials: A
authors.lastname: Doria
authors.forename: G
authors.initials: G
authors.lastname: Brambilla
authors.forename: A
authors.initials: A
authors.lastname: Angelini
authors.forename: A
authors.initials: A
authors.lastname: Ghirardello
authors.forename: S
authors.initials: S
authors.lastname: Bottaro
authors.forename: F
authors.initials: F
authors.lastname: Tona
authors.forename: C
authors.initials: C
authors.lastname: Betterle
authors.forename: L
authors.initials: L
authors.lastname: Daliento
authors.forename: G
authors.initials: G
authors.lastname: Thiene
authors.forename: S
authors.initials: S
authors.lastname: Iliceto
mesh_terms: D000208:Acute Disease; D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000276:immunology*; D015551:Autoimmunity; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000276:immunology*; D032383:Myocytes, Cardiac / Q000276:immunology; D010493:Pericarditis / Q000276:immunology*; D012008:Recurrence; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D015415:Biomarkers