title: A TSHr-LH/CGr chimera that measures functional TSAb in Graves' disease.
abstract: BACKGROUND
  Stimulating thyrotropin receptor (TSHr) autoantibodies (TSAb) are the cause of hyperthyroidism in Graves' disease. In a patient's serum, TSAb can coexist with antagonist TSHr autoantibodies that block TSAb stimulatory activity (TSBAb); both can vary in amount and time.
  
  
  OBJECTIVE
  The objective of the study was to create a functional assay that detects only TSAb, thus having an increased accuracy for diagnosing Graves' disease.
  
  
  METHODS
  A TSHr chimera (Mc4) that retains an agonist-sensitive TSAb epitope but replaces a TSBAb epitope was stably transfected in cells to establish the Mc4 assay.
  
  
  METHODS
  The study was conducted at the Chieti University (Outpatient Endocrine Clinic) and the University of Pisa (the Department of Endocrinology).
  
  
  METHODS
  The assay was validated using sera from 170 individuals with Graves' disease, Hashimoto's thyroiditis, and nonautoimmune hyperthyroidism and normal subjects from Chieti University. A second blinded study evaluated sera from 175 patients with autoimmune thyroid disease (mainly Graves' disease) from the University of Pisa.
  
  
  METHODS
  Interventions included the assessment of patients' sera using human wild-type TSHr (WT-TSHr), Mc4 chimera, and binding (TRAb) assays.
  
  
  METHODS
  The Mc4 assay has the best accuracy for diagnosing Graves' disease.
  
  
  RESULTS
  The Mc4 assay has a better diagnostic accuracy than WT-TSHr and second-generation TRAb assays. Indeed, the sensitivity of the WT-TSHr, TRAb, and Mc4 assays was 97.3, 86.5, and 100%, respectively, whereas the specificity was 93.1, 97, and 98.5%, respectively.
  
  
  CONCLUSIONS
  The Mc4 assay is a functional assay with improved sensitivity and specificity for the detection of TSAb and is clinically useful in diagnosing Graves' disease.
authors.affiliation: Unit of Endocrinology, Department of Medicine and Sciences of Aging, University "G. D'Annunzio" and Aging Research Center, Centro Scienze dell'Invecchiamento, "Gabriele D'Annunzio" University Foundation, 66013 Chieti-Pescara, Italy.
authors.forename: Cesidio
authors.initials: C
authors.lastname: Giuliani
authors.forename: Dominique
authors.initials: D
authors.lastname: Cerrone
authors.forename: Norikazu
authors.initials: N
authors.lastname: Harii
authors.forename: Mark
authors.initials: M
authors.lastname: Thornton
authors.forename: Leonard D
authors.initials: LD
authors.lastname: Kohn
authors.forename: Nilesh M
authors.initials: NM
authors.lastname: Dagia
authors.forename: Emilio
authors.initials: E
authors.lastname: Fiore
authors.forename: Ines
authors.initials: I
authors.lastname: Bucci
authors.forename: Tyler
authors.initials: T
authors.lastname: Chamblin
authors.forename: Paolo
authors.initials: P
authors.lastname: Vitti
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Monaco
authors.forename: Giorgio
authors.initials: G
authors.lastname: Napolitano
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001323:Autoantibodies / Q000032:analysis / Q000097:blood; D016466:CHO Cells; D016022:Case-Control Studies; D002478:Cells, Cultured; D006224:Cricetinae; D005260:Female; D006111:Graves Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating / Q000032:analysis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D008907:Mink; D011974:Receptors, LH / Q000032:analysis* / Q000737:chemistry / Q000502:physiology; D011989:Receptors, Thyrotropin / Q000032:analysis* / Q000737:chemistry / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000032:analysis; D013960:Thyroid Function Tests / Q000379:methods
chemical_list: D001323:Autoantibodies; D018828:Immunoglobulins, Thyroid-Stimulating; D011974:Receptors, LH; D011989:Receptors, Thyrotropin; D011993:Recombinant Fusion Proteins; C118905:thyroid stimulation-blocking antibody