Axonal degeneration accompanied by conduction block induced by toxin mediated immune reactivity to GM1 ganglioside in rat nerves

Immune mechanisms have been implicated in the pathogenesis of motor neuropathy with conduction blocks and of acute axonal neuropathy, and GM1 ganglioside has been identified as a potential target antigen. In these experiments, the B subunit of cholera toxin (CT-B), which binds to GM1, was used to target an antibody response to GM1 in peripheral nerve. CT-B was injected into the sciatic nerves of rats, in which anti-CT antibodies were previously induced by immunization, so that the circulating anti-CT-B antibodies bound to the CT-B-GM1 complex in the nerve. Electrophysiological studies revealed the presence of conduction block, and in pathological studies there was axonal degeneration with little demyelination. Control animals, in which keyhole limpet hemocyanin was substituted for CT, did not develop conduction block or axonal degeneration. These studies indicate that antibodies directed at GM1 sites in peripheral nerve could cause an axonal neuropathy with conduction block.