Hybrid gangliosides for the detection of anti-ganglioside complex antibodies

Gangliosides are glycosphingolipids that are concentrated in the outer leaflet of neuronal membranes with exposure of their oligosaccharides on the cell surface. Guillain-Barre´ syndrome (GBS) is acute autoimmune neuropathy, often subsequent to an infection. Antiganglioside antibodies are often closely associated with clinical phenotype and specific symptoms of GBS. Recent studies demonstrated that some GBS patients had serum antibodies that specifically recognize the novel glycoepitopes formed by two individual ganglioside molecules and named such antibodies as ‘anti-ganglioside complex (GSC) antibodies’. Those antibodies can be used as diagnostic markers of GBS. Conventional measurement of antiganglioside antibodies has been done for purified single ganglioside antigens using enzyme-linked immunosorbent assays (ELISAs) or thin-layer chromatogram (TLC)-immunostaining. The availability of several hybrid gangliosides, containing two or more oligosaccharide chains and the availability of simple analytical approaches opens new perspectives for the understanding and therapy of several neuropathies. For this purpose we prepared the dimeric hybrid GM1-GD1a ganglioside derivative that contains two structural different oligosaccharide chains. A mixture of the two natural gangliosides was described to be recognized by the sera from patients with specific and clinical characterized GBS. We prepared the GM1-GM1 and GD1a-GD1a dimers to be used as controls. After removal of the acyls and reconstitution of the original acetylated sugars, the lyso-gangliosides, were connected with adipic acid to form the hybrid compound, a same-how mimic of the heterogeneous plasma membrane cluster of gangliosides. The dimeric hybrid GM1-GD1a was very well recognized by the GBS serum. However no reactivity was observed with the patient serum and the dimeric GM1 and dimeric GD1a. This suggests that both the GM1 and GD1a chain are necessary for a strong interaction and to maintain stable the antibody-antigen complex.