Do neurofascin antibodies disrupt nerve-signal conduction?

Mechanistic pathways of node disruption

• Isoform-specific targeting: Autoantibodies directly target neurofascin-155 (NF155) at the glial paranodal junction and neurofascin-186 (NF186) at the axonal node of Ranvier. Normally, NF155 complexes with axonal contactin-1 and Caspr1 to organize the axo-glial junction, which isolates voltage-gated sodium channels at the node and potassium channels at the juxtaparanode.
• Paranodal dissection and channel mislocalization: Antibodies targeting NF155 (predominantly the IgG4 subclass) cause a steric blockade that results in "paranodal dissection"—the physical detachment of terminal myelin loops from the axon. This breaks the axo-glial barrier, allowing potassium channels (Kv1) to invade the node and destabilize sodium (Nav) channel clusters.
• Complement-mediated injury: Conversely, IgG1 and IgG3 antibodies targeting NF186 initiate complement-dependent nodal injury, directly declustering sodium channels at the node of Ranvier without requiring paranodal disruption.

Physiological and clinical implications

• Conduction failure: Both pathogenic pathways compromise the electrical safety factor required for saltatory conduction. The loss of molecular compartmentalization leads directly to conduction slowing, prolonged distal latencies, and conduction block.
• Reversible pathophysiology: Because this immune reactivity target-specifically disrupts nodal architecture rather than causing classic macrophage-mediated demyelination, removing these pathogenic antibodies can rapidly restore nerve-signal conduction.

Bottom line

• Neurofascin antibodies disrupt nerve-signal conduction by driving localized immune reactivity—either via IgG4-mediated steric detachment of myelin loops or IgG1/IgG3 complement-mediated nodal damage—which mislocalizes the ion channels necessary for saltatory conduction.