ギラン・バレー症候群における糖脂質抗体の展開—フィッシャー症候群関連病態とCa2＋依存性糖脂質抗体

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

糖脂質抗体研究を軸に，ギラン・バレー症候群の病態解明は進んだ。単独抗原の検討から始まった糖脂質抗体研究は，2つの糖脂質の複合抗原に対する抗体の発見により，その領域をさらに拡大した。最近，ガングリオシドGQ1bとの反応にCa^2＋を必要とする抗体（Ca^2＋依存性GQ1b抗体）が，フィッシャー症候群関連病態で発見された。Ca^2＋はGQ1bのジシアロシル基と相互作用し，抗体はそのCa^2＋が結合した構造を認識していると考えられる。

Abstract

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.