Figure 1: Effect of serum, IgG and IgG anti M3 autoantibodies from patients with primary Sjögren syndrome (pSS) evaluated by enzyme immunoassay (ELISA). UPPER PANEL: Dose-response curve of different serum dilution (A), different concentration of pSS IgG (B) and different concentration of pSS IgG anti M3 (C) autoantibodies of pSS patients (●) against M3 mAChR synthetic peptide. The values of normal sera and normal IgG and normal IgG anti M3 (■) is also shown. *P<0.0001 versus serum,IgG and IgG anti M3 of normal individuals. MIDDLE PANEL: Scatterogram showing immunoreactivity of pSS serum (D), pSS IgG (E) and pSS IgG anti M3 (F) of SS patients (●) and normal individuals (■) against M3 synthetic peptide. The individual optical density (OD) values for each serum sample or pSS IgG or pSS IgG anti M3 were taken from 30 normal individuals and 30 patients with pSS. OD values more than 2 SD above the normal mean, were taken as positive. Cut off value of OD: D=0.25 ± 0.05, E= 0.24 ± 0.06 and F= 0.18 ± 0.03 respectively. LOWER PANEL: Influence of 1x10-6 M atropine (unspecific mAChR antagonist), 1x10-8 M J104129 (specific M3 mAChR antagonist) and 5x10-7 M anti M3 synthetic peptide on the maximal dilution or concentration of serum (G), pSS IgG (H) and pSS IgG anti M3 (I) respectively.The values of normal sera and normal IgG and normal IgG anti M3 is also shown. Values are mean ± SEM from a pool of 30 pSS patients and 30 normal individuals.*P< 0.0001 versus normal (n) serum or IgG; **P<0.001 versus pSS serum or pSS IgG. All the experiments were performed by duplicates.