Ca(2+)-dependent anti-GQ1b antibody in GQ1b-seronegative Fisher syndrome and related disorders.
Although serum IgG anti-ganglioside GQ1b antibody is the most specific biomarker for Fisher syndrome and its related disorders (FS-RD), 10%-30% of the patients are still negative in conventional assays ("GQ1b-seronegative") and the relationship between GQ1b-seropositive and -seronegative patients has been unclear. Some molecules require Ca(2+) cations to interact with their ligands (Ca(2+)-dependency). Here we have investigated whether Ca(2+)-dependency is also present in anti-GQ1b antibodies in FS-RD, especially in the GQ1b-seronegative patients and show that IgG antibodies against GQ1b-related antigens (isolated GQ1b and GQ1b-containing complexes) are detected Ca(2+)-dependently in the majority of GQ1b-seronegative patients with FS-RD. The Ca(2+)-dependent antibodies might react specifically with GQ1b-Ca(2+) conformation. This is the first demonstration of disease-related Ca(2+)-dependent antibodies in neurological field. GQ1b-related pathology would be involved in FS-RD more extensively than previously revealed.
Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
Ayumi
A
Uchibori
Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
Atsuko
A
Gyohda
Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan. Electronic address: achiba-tky@umin.ac.jp.
Atsuro
A
Chiba
D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood*; D002118:Calcium / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005732:Gangliosides / Q000097:blood* / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019846:Miller Fisher Syndrome / Q000097:blood* / Q000150:complications; D012720:Severity of Illness Index; D055815:Young Adult
D000888:Antibodies, Anti-Idiotypic; D005732:Gangliosides; C048844:anti-IgG; C039129:GQ1b ganglioside; D002118:Calcium
Anti-GQ1b antibody; C-type lectin; Ca(2+)-dependent antibody; Fisher syndrome; Ganglioside complex