Résumé
This review discusses the immunology of gangliosides from the perspective of tumor, neuronal and general immunology. Antiganglioside antibodies in human sera are invariably IgM and are found in healthy individuals. Their titers decline with age. Persistent high titer of IgM is associated with several diseases, particularly neuropathies. Membrane-bound gangliosides are important tumor-associated antigens and targets for immune attack. Cells enriched with gangliosides can be used as cancer vaccines. Efficacy of these vaccines depends on the viability of whole cells, integrity of the cell membranes, adjuvants and topography of the tumor-associated antigens. The role of antiganglioside IgM is to eliminate the immunosuppressive gangliosides shed from tissues during ageing, degeneration of neural and extraneural tissues, and tumor growth and necrosis. In addition, in vitro observations with human and murine monoclonal antibodies suggest that they are capable of complement dependent cytotoxicity and apoptosis.
Sujets)
Animaux , Antigènes/composition chimique , Autoanticorps/sang , Marqueurs biologiques , Séquence glucidique , Gangliosides/composition chimique , Humains , Immunoglobuline M/sang , Souris , Données de séquences moléculairesRésumé
Sugar-specific binding of bovine brain 14 kDa galactose-binding lectin (BBL) to individual endogenous gangliosides (GM1, GM2, GD1a, GD1b and GT1b) was studied using affinity electrophoresis of ganglioside-lectin mixture in polyacrylamide gel at pH 8.3. Unbound (free) lectin moved ahead while ganglioside-lectin complex moved very little. Sugar-specificity of binding was confirmed by reversal of the interaction by (i) presence of lactose along with the lectin and (ii) pretreatment of gangliosides with another galactose-binding lectin, Ricinus communis agglutinin. Stoichiometry of ganglioside-BBL interaction revealed that GT1b had the highest affinity for the lectin followed by GD1b and GM2, while GM1 and GD1a had the least affinity. Results indicated that a terminal sialic acid moiety covering a galactose moiety may at times enhance BBL recognition of the latter and that changes in ganglioside pattern is a possible modulator of lectin function in vivo.
Sujets)
Animaux , Fixation compétitive , Encéphale/métabolisme , Bovins , Électrophorèse sur gel de polyacrylamide , Galectines , Gangliosides/composition chimique , Hémagglutinines/métabolisme , Lactose/métabolisme , Lectines/métabolisme , Acide N-acétyl-neuraminique/métabolisme , Lectines végétalesRésumé
The aggregative and geometrical properties of gangliosides have been compared and discussed. It is shown that, due to the steric packing features of gangliosides, significative considerations can be made on the primary and secondary structures of their head group, starting from their cooperative behaviour, supporting NMR direct observations.