Myasthenogenicity of a human acetylcholine receptor alpha-subunit peptide: morphology and immunology.

Each of 10 rats inoculated with a synthetic peptide comprising residues 125-147 (without a disulfide bond) of human acetylcholine receptor (AChR) alpha-subunit (H alpha) had deposits of IgG and C3 (immune complexes) and showed morphological changes in the fine structure at the motor end-plates 5 weeks after a single immunization. Antibody to the H alpha peptides was elevated 1 week after immunization, but, antibody levels to solubilized human or rat AChR were very low in 8 of the 10 rats. These results suggest that the immune response to peptide H alpha is the myasthenogenic site, which induces morphological change at the end-plates.