[A New Aspect of Anti-Glycolipid Antibodies in Guillain-Barré Syndrome: Ca2+-Dependent Antibody in Fisher Syndrome-Related Disorders].

Anti-glycolipid antibodies are key to revealing the pathomechanisms of Guillain-Barré syndrome (GBS). There are correlations between the antigen specificities of the antibodies, clinical features, and preceding infectious agents. It has also been found that some glycoantigens are localized in human peripheral nervous tissues, corresponding to the clinical features. Antibody-detection methods are still evolving. The discovery of antibodies against glycolipid complexes expanded the horizon of anti-glycolipid research in GBS, which had started from isolated antigens. Recently, IgG antibodies against ganglioside GQ1b-related antigens that required Ca2+ cations in the antigen-antibody reaction (Ca2+-dependent anti-GQ antibody) have also been detected in patients with Fisher syndrome, or other related disorders, who were GQ1b-seronegative in conventional assays without adding Ca2+. It is suggested that Ca2+ interacts with disialosyl groups [NeuAc (a2-8) NeuAc (a2-)] in gangliosides, and that the Ca2+-dependent antibodies recognize the Ca2+-bound conformation of GQ1b.