title: Clinical associations of autoantibodies to human muscarinic acetylcholine receptor 3(213-228) in primary Sjogren's syndrome.
abstract: OBJECTIVE
  The authors have previously identified a peptide of the human muscarinic acetylcholine receptor-3 (m3AChR) as a suitable antigen for the immunodetection of antimuscarinic acetylcholine receptor autoantibodies in primary Sjögren's syndrome (pSS). The aim of this study was to assess the clinical correlations and disease specificity of these antibodies.
  
  
  METHODS
  Seventy-three pSS, 40 rheumatoid arthritis (RA), 19 systemic lupus erythematosus (SLE), 14 secondary Sjögren's syndrome (sSS) patients, 22 subjects in whom pSS was suspected but in whom the diagnosis not could eventually be established (suspSS) and 40 healthy subjects were investigated. An enzyme-linked immunosorbent assay system developed by the authors using a 16-mer peptide of the m3AChR (m3AChR(213-228)) in a recombinant fusion peptide form was used as the antigen.
  
  
  RESULTS
  Anti-m3AChR(213-228) antibody positivity was observed in 66 (90%) of the pSS patients. The antibody levels correlated positively with the number of extraglandular organ manifestations. Both the mean antibody levels and the occurrence of anti-m3AChR(213-228) positivity were significantly higher in pSS than in the comparison groups. The test discriminated the pSS patients from the various comparison groups with specificities of 65, 68, 71 and 50% for RA, SLE, sSS and suspSS, respectively.
  
  
  CONCLUSIONS
  The presence of m3AChR(213-228) antibodies is a common feature in pSS. Although it is significantly more common in pSS than in the comparison groups, anti-m3AChR(213-228) positivity is not exclusive to pSS.
authors.affiliation: Department of Rheumatology, University of Szeged, Pécs, Hungary. kovl@in1st.szote.u-szeged.hu
authors.forename: L
authors.initials: L
authors.lastname: Kovács
authors.forename: I
authors.initials: I
authors.lastname: Marczinovits
authors.forename: A
authors.initials: A
authors.lastname: György
authors.forename: G K
authors.initials: GK
authors.lastname: Tóth
authors.forename: L
authors.initials: L
authors.lastname: Dorgai
authors.forename: J
authors.initials: J
authors.lastname: Pál
authors.forename: J
authors.initials: J
authors.lastname: Molnár
authors.forename: G
authors.initials: G
authors.lastname: Pokorny
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008875:Middle Aged; D043587:Receptor, Muscarinic M3 / Q000276:immunology*; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000175:diagnosis / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D043587:Receptor, Muscarinic M3