To evaluate whether or not the changes in the secretions of IL-17 and IFN-γ can be induced by the immunization with 2nd extracellular loop peptide of muscarinic acetylcholine 3 receptor (M3R) in NOD-scid (nonobese diabetic-severe combined immunodeficiency) mice.
We synthesized the 2nd extracellular loop peptide of M3R and immunized NOD-scid mice subcutaneously with the 1:1 mixture of the peptide and the incomplete Freund's adjuvant (IFA). At day 1,  7,  14,  21 after immunization,  tail blood samples were taken to determine the antibody titer and evaluate the secretions of IL-17 and IFN-γ in sera. Meanwhile,  we recorded the fluid intake amount per mouse every week. At day 21,  all of the NOD-scid mice were killed to measure the concentrations of IL-17 and IFN-γ in cell supernatants. Immunofluorescence staining of lacrimal glands was performed to observe the changes in the secretions of IL-17 and IFN-γ.
Compared with the control group,  the sera titers of anti-2nd extracellular loop peptide antibodies were significantly higher in 2nd extracellular loop peptide immunized NOD-scid mice at day 14 (P<0.05). The concentrations of IL-17 and IFN-γ increased significantly in sera of the 2nd extracellular loop peptide immunized NOD-scid mice at day 7 and 14 (P<0.01). The concentration of IL-17 maintained at a certain level in the supernatants of spleen cells co-cultured with 2nd extracellular loop peptide,  while it decreased significantly in the control  groups (P<0.01). Immunofluorescence staining demonstrated that the production of IL-17 and IFN-γ increased in the lacrimal glands of NOD-scid mice immunized with the 2nd extracellular loop peptide. However,  no changes in fluid intake was observed in NOD-scid mice immunized with the 2nd extracellular loop peptide(P>0.05).
Immunization with 2nd extracellular loop peptide of M3R can induce the production of anti-2nd extracellular loop peptide antibodies and the secretions of IL-17 and IFN-γ in NOD-scid mice.