Gangliosides, GM1 and GQ1b, are respectively major immunological target molecules in Guillain–Barré syndrome and Fisher syndrome. In enzyme-linked immunosorbent assay, the addition of acidic phospholipids increases the activities of anti-GM1 antibodies, but not of anti-GQ1b antibodies, suggesting different physicochemical properties of GM1 and GQ1b. On the axolemma, gangliosides form clusters termed “rafts”, and the environment surrounding the clusters possibly modulates the activity of the autoantibodies.