Sayako Hotta, Takumi Nagaoka, Yoshihiko Nakatani, Toshie Kambe, Kenji Abe, Yutaka Masuda, Iku Utsunomiya and Kyoji Taguchi
Guillain-Barré syndrome with antibodies against ganglioside N-acetylgalactosaminyl GD1a (GalNAc-GD1a) is
characterized by a rapid onset of predominantly distal pure motor neuropathy. However, the pathogenic role of anti-
GalNAc-GD1a antibody and calcium channels in neuromuscular junctions (NMJs) remains unclear. We investigated
the effects of IgM anti-GalNAc-GD1a monoclonal antibody (IgM anti-GalNAc-GD1a mAb) on spontaneous muscle
action potentials (SMAP) in a rat spinal cord–muscle co-culture system and the localization of IgM anti-GalNAc-
GD1a mAb and calcium channel binding in the rat hemi-diaphragm. Immunohistochemistry of the rat hemidiaphragm
showed that IgM anti-GalNAc-GD1a mAb binding overlapped with anti-neurofilament 200 antibody and α-
bungarotoxin staining, demonstrating that IgM anti-GalNAc-GD1a mAb was localized at the motor nerve terminal.
Moreover, IgM anti-GalNAc-GD1a mAb binding overlapped with anti-Cav2.1 antibody in the nerve terminal. We
suggest that the inhibitory effect of IgM anti-GalNAc-GD1a mAb on SMAP is related to the GalNAc-GD1a epitope on
P/Q-type calcium channels in motor nerve terminals at NMJs.