Acute canine idiopathic polyneuropathy (ACIP) serum demyelinates peripheral nerve in vivo

Animal models of autoimmune neuropathy

The peripheral nervous system (PNS) comprises the cranial nerves, the spinal nerves with their roots and rami, dorsal root ganglia neurons, the peripheral nerves, and peripheral components of the autonomic nervous system. Cell-mediated or antibody-mediated immune attack on the PNS results in distinct clinical syndromes, which are classified based on the tempo of illness, PNS component(s) involved, and the culprit antigen(s) identified. Insights into the pathogenesis of autoimmune neuropathy have been provided by ex vivo immunologic studies, biopsy materials, electrophysiologic studies, and experimental models. This review article summarizes earlier seminal observations and highlights the recent progress in our understanding of immunopathogenesis of autoimmune neuropathies based on data from animal models.

In vitro demyelination by serum antibody from patients with Guillain-Barré syndrome requires terminal complement complexes

Serum from 7 patients who had acute-phase Guillain-Barré syndrome with high anti-peripheral nerve myelin antibody activity (54 to 210 units/ml) was compared with serum from 3 patients in the recovery phase (0 to 17 units/ml) and serum from 7 disease control subjects (0 to 24 units/ml) and 7 normal control subjects (0 to 7 units/ml) for its ability to demyelinate rodent dorsal root ganglion cultures. The demyelinating capacity of each serum was quantitated by counting the percent of damaged internodal segments in each of four cultures. All sera from patients in the acute phase GBS caused 50 to 78% demyelination, in contrast with 6 to 19% by the sera from all 3 patients in the recovery phase and all other control subjects. The degree of demyelination correlated with anti-peripheral nerve myelin antibody activity of the sera and demyelination was complement-dependent. Further, cultures were treated with an immunoglobulin M (IgM) fraction of an acute-phase Guillain-Barré syndrome plasma plus normal human serum depleted of complement component C7. Only those cultures treated with IgM and C7-depleted human serum reconstituted with purified C7 resulted in 50.8% demyelination, which was significantly greater than the 14.2 to 16.2% demyelination observed in the presence of heat-inactivated, C7-depleted human serum plus purified C7 or in the absence of C7 or antibody. In summary, our work suggests that anti-peripheral nerve myelin antibody in Guillain-Barré syndrome mediated complement dependent-demyelination of rodent dorsal root ganglion cultures. Further, this in vitro demyelination required generation of activation complexes of the terminal complement cascade.

Demyelination in vivo by Guillain-Barré syndrome and other human serum

Serum from patients with acute inflammatory polyneuropathy (the Guillain-Barré syndrome, GBS) demyelinates peripheral nerves in vivo more intensely than control human serum. To clarify the processes leading to demyelination we injected rat sciatic nerves with serum from GBS and control subjects in the presence of complement and examined the sequential morphologic changes over 7 days. One day after injection, five of six GBS sera but none of seven control sera caused vesicular demyelination; 3-5 days after injection both GBS and control sera produced macrophage-mediated demyelination. These observations suggest that GBS serum can initiate acute myelin injury through a humoral mechanism that is disease associated. This response appears to be distinct from delayed cell-mediated serum-induced demyelination that is not disease specific.