Vaccination with a MHC class II peptide attenuates cellular and humoral responses against tAChR and suppresses clinical EAMG

An animal model of myasthenia gravis (MG), termed experimental autoimmune MG (EAMG), can be induced in C57BL/6 (B6, H-2^b) mice by immunization with Torpedo californica acetylcholine receptor (tAChR). We have investigated the effect of vaccination with MHC class II peptide I-Aβ^b62-76 on clinical EAMG and on T cell and antibody (Ab) responses against tAChR. B6 mice were vaccinated with the peptide (25 μg/mouse) four times prior to two injections with tAChR. The incidence of clinical EAMG in vaccinated mice was 14% (3 out of 22 mice) compared to 48% (17 out of 35 mice) in control non-vaccinated or PBS-immunized mice. The T cells of the vaccinated group showed lower proliferative responses to tAChR and to T-cell epitope-containing tAChR α-chain peptides than the T cells of controls. In addition, the Ab responses in the vaccinated group was also lower against tAChR and some of the B-cell epitope-containing tAChR α-chain peptides.