Objectives. 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 (m3AChR213-228) in a recombinant fusion peptide form was used as the antigen. Results. Anti-m3AChR213-228 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-m3AChR213-228 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 m3AChR213-228 antibodies is a common feature in pSS. Although it is significantly more common in pSS than in the comparison groups, anti-m3AChR213-228 positivity is not exclusive to pSS.
- Antimuscarinic acetylcholine receptor-3 autoantibody
- Disease specificity
- Muscarinic acetylcholine receptor-3
- Primary Sjögren's syndrome
ASJC Scopus subject areas
- Pharmacology (medical)