Experimental conduction block induced by serum from a patient with anti‐GM1 antibodies

TLDR

High anti‑GM1 antibody titers are associated with lower motor neuron disease and motor neuropathy, often accompanied by conduction block. The study aimed to investigate how anti‑GM1 antibodies cause conduction block by injecting patient serum into rat sciatic nerve. Serum from a patient with anti‑GM1 antibodies was injected into rat sciatic nerve to assess its effect. Injection of the serum with fresh human complement produced conduction block with temporal dispersion, immunoglobulin deposits at the nodes of Ranvier, and 6.5 % demyelination; pre‑absorption with GM1 eliminated these effects, confirming the antibodies’ role.

Abstract

Abstract Increased titers of antibodies to GM1 ganglioside in humans are associated with lower motor neuron disease and predominantly motor neuropathy with or without conduction block. To investigate the possible mechanism of these antibodies, we injected the serum of a patient with anti‐GM1 antibodies who had motor neuron disease and multifocal motor conduction block, into rat sciatic nerve. When injected with fresh human complement, the serum‐induced conduction block with temporal dispersion and deposits of immunoglobulin were detected at the nodes of Ranvier. Electron microscopic studies revealed demyelination in 6.5% of the fibers. After preabsorbtion with GM1, the serum had no effect, suggesting that the anti‐GM1 antibodies were responsible for the conduction abnormalities.