Anti-GD1a antibodies from an acute motor axonal neuropathy patient selectively bind to motor nerve fiber nodes of Ranvier.

Acute motor axonal neuropathy (AMAN) is associated with high titer anti-GD1a antibodies. We have found that very high titer IgG anti-GD1a antibodies (Ab) from one AMAN patient selectively bind to motor, but not sensory, nerve nodes of Ranvier. Binding is abolished by preadsorption with GD1a. Sera negative for Ab do not immunostain motor and sensory nerve roots. We have also found that botulinum toxin A (BTA), which binds to GD1a, stains both motor and sensory nerve nodes of Ranvier. Our results strongly support the pathogenetic role of anti-GD1a antibodies in AMAN. Why BTA also binds to sensory fibers still remains to be elucidated, although the different size of BTA and its specificity to other gangliosides present in sensory axons might represent important factors.