Peptide-based ELISAs are not sensitive and specific enough to detect muscarinic receptor type 3 autoantibodies in serum from patients with Sjogren's syndrome.
OBJECTIVE
The detection of autoantibodies to the muscarinic receptor type 3 (M3R) in the serum of patients with Sjögrens syndrome (SS) by ELISA is controversial. A study was undertaken to test whether modification of M3R peptides could enhance the antigenicity and increase the detection of specific antibodies using an ELISA.


METHODS
A series of controlled ELISAs was performed with serum from 71 patients with SS and 37 healthy volunteers (HV) on linear, citrullinated and/or cyclised and multi-antigenic peptides (MAP) of the three extracellular M3R loops to detect specific binding.


RESULTS
Significant differences (p<0.05) in optical density (OD) between serum from patients and HV were detected for a cyclised loop 1-derived peptide and the negative control peptide. Furthermore, there were no statistically significant differences between the frequency of positive patients (defined as OD >2SDs above the mean of the HV) and HV on any of the peptides tested.


CONCLUSIONS
Binding of serum from patients with SS to M3R-derived peptides does not differ from binding to a control peptide in an ELISA and no significant binding to M3R-derived peptides was found in the serum from individual patients compared with HV. These data suggest that peptide-based ELISAs are not sufficiently sensitive and/or specific to detect anti-MR3 autoantibodies.
Roescher
N
N
Kingman
A
A
Shirota
Y
Y
Chiorini
J A
JA
Illei
G G
GG
D001323:Autoantibodies / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D043587:Receptor, Muscarinic M3 / Q000276:immunology*; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000276:immunology*
D001323:Autoantibodies; D043587:Receptor, Muscarinic M3