title: Anti-β-adrenoceptors autoimmunity causing 'idiopathic' arrhythmias and cardiomyopathy.
abstract: BACKGROUND
  To determine the prevalence of anti-β-adrenoceptors autoantibodies (aβAA) in patients with idiopathic arrhythmias (IA) and to assess whether aβAA are predictive markers for concealed cardiomyopathy in such patients.
  
  
  RESULTS
  Sixty-seven patients (group 1) with IA [25 supraventricular (SVA) and 42 ventricular (VA)]; 14 patients (group 2) with suspected cardiomyopathy, 12 patients with definite cardiomyopathy (group 3); and 19 healthy controls (group 4) were tested with an enzyme immunoassay, using synthetic peptides corresponding to the second extracellular loop of the human β1-and β2-adrenoceptors. Endomyocardial biopsy was performed in 29 patients. As compared with group 4 [3/19 (15.7%)], anti-β1-adrenoceptor autoantibodies (aβ1AA) were more frequent in group-1 patients [38/67 (56.7%; P<0.01): 27/42 (64.2%; P<0.001) with VA and 11/25 (44%; P<0.05) with SVA]. 3 of the group 1 patients also had anti-β2-adrenoceptor autoantibodies (aβ2AA). 4 were positive for aβ2AA only. Biopsy performed in 11/67 group 1 patients was abnormal in all. Of them, 7/8 (87.5%) with VA and 3/3 (100%) with SVA were positive for aβ1AA. PCR analysis from paraffin blocks of the 11 group 1 biopsied patients was negative for EV, EBV, HCV, AV, PVB19, INF A/B,HSV1/2, HHV6 and HHV8 viral genomes.
  
  
  CONCLUSIONS
  The second extracellular loop of the β-adrenoceptor is the molecular target of specific autoantibodies. Positivity for aβ1AA predicts abnormal histological findings in 90% of IA patients and suggests that autoimmunity might play an arrhythmogenic role.
authors.affiliation: Centro di Biomagnetismo - Fisiologia Clinica, Università Cattolica del Sacro Cuore, Roma, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Brisinda
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Sorbo
authors.forename: Angela
authors.initials: A
authors.lastname: Venuti
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Ruggieri
authors.forename: Raffaele
authors.initials: R
authors.lastname: Manna
authors.forename: Peter
authors.initials: P
authors.lastname: Fenici
authors.forename: Gerd
authors.initials: G
authors.lastname: Wallukat
authors.forename: Johan
authors.initials: J
authors.lastname: Hoebeke
authors.forename: Andrea
authors.initials: A
authors.lastname: Frustaci
authors.forename: Riccardo
authors.initials: R
authors.lastname: Fenici
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D001323:Autoantibodies / Q000032:analysis*; D015551:Autoimmunity; D001706:Biopsy; D009202:Cardiomyopathies / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D018604:Epitope Mapping; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000276:immunology* / Q000473:pathology; D011487:Protein Conformation; D018342:Receptors, Adrenergic, beta-1 / Q000737:chemistry / Q000276:immunology*; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry / Q000276:immunology*; D055815:Young Adult
chemical_list: C547787:ADRB1 protein, human; C553443:ADRB2 protein, human; D001323:Autoantibodies; D018342:Receptors, Adrenergic, beta-1; D018343:Receptors, Adrenergic, beta-2