[Immune-mediated neuropathy and anti-glycolipid antibodies].

Antibodies to glycolipids likely play a pathogenic role in the development of immune-mediated neuropathy. Guillain-Barre syndrome (GBS), an acute immune-mediated polyradiculoneuropathy, often has IgG antibodies to gangliosides, sialic acid-containing glycolipids. The heterogeneity of ganglioside expression in the peripheral nervous system (PNS) may underlie the differential clinical manifestation of GBS variants. Recent studies show that anti-ganglioside antibody-mediated complement activation plays a key role in the development of GBS and related disorders. Futher, complement-independent nerve dysfunction has been suggested by in vitro studies that anti-ganglioside antibodies directly inhibit voltage-gated Ca2+ channel currents and change the integrity of lipid rafts. These pathogenic actions of anti-ganglioside antibodies may be governed by the avidity of the antibodies, which is influenced by the specific localization of target gangliosides in the PNS, the glycolipid environment around the target antigens, the large amount of targeted gangliosides in specific regions, the steric microstructure of sialic acids in the gangliosides, or conformation of the glycoepitopes that are dependent upon the length of ceramide fatty acids. The recent discovery of antibodies to ganglioside complexes (GSC) consisting of 2 different gangliosides improves the detection rate of autoantibodies in GBS, as well as provides a new concept in antibody-antigen interactions through clustered carbohydrate epitopes, thereby expediting the understanding of the mechanisms underlying antibody-mediated nerve dysfunction in GBS and its variants. In chronic immune-mediated neuropathy, antibodies to GSCs such as GM1/LM1 or GD1b/LM1 have been identified, although their pathophysiological roles remain to be determined.