Antibodies to ganglioside complexes consisting of asialo-GM1 and GQ1b or GT1a in Fisher and Guillain-Barré syndromes.

To determine the epitopes of ganglioside complexes (GSCs) containing GQ1b or GT1a, we investigated their reactivity to GSCs consisting of asialo-GM1 (GA1) and GQ1b or GT1a using IgG anti-GQ1b- or anti-GT1a-positive sera. Nine anti-GQ1b-positive sera had higher activity to GA1/GQ1b than to GQ1b, only five of which reacted with GM1/GQ1b and GD1b/GQ1b. Five of 14 sera positive for GA1/GT1a and GM1/GT1a were negative for GA1/GQ1b and GM1/GQ1b. Sialic acids attached to the internal galactose of gangliotetraose can influence the reactivity of anti-GSC antibodies. Screening for antibodies to GSCs containing GA1 is useful for elucidation of the antibody-mediated pathophysiology.