title: Chemical residues of ganglioside molecules involved in interactions with lymphocyte surface targets leading to CD4 masking and inhibition of mitogenic proliferation.
abstract: Human lymphocyte CD4 becomes undetectable in the presence of exogenous gangliosides (CD4 masking), as originally described by Offner et al. (J. Immunol. 1987. 139: 3295). CD4 masking is apparently due to in situ rearrangement of the glycoprotein; since no direct binding of ganglioside to CD4 could be demonstrated, it was suggested that the effect could be mediated by interactions with other, as yet unidentified, surface structures. To gain insight into the structural requirements of the interaction(s) that leads to CD4 masking, we assayed the effects of a battery of gangliosides and of ganglioside derivatives on (a) CD4 masking; (b) cholera toxin binding (as a well known ganglioside-protein interaction) and (c) inhibition of lymphocyte mitogenic proliferation (as a second ganglioside interaction with a lymphocyte surface target). Our results indicate that the three interactions are distinctly different, since ganglioside chemical groups which are essential for one of the interactions are irrelevant for the others, and lead to the conclusion that gangliosides can interact with lymphocyte surface targets in a number of ways, causing a number of independent biological effects.
authors.affiliation: Dipartimento di Biologia Genetica per le Scienze Mediche, Università di Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Grassi
authors.forename: L
authors.initials: L
authors.lastname: Lopalco
authors.forename: P
authors.initials: P
authors.lastname: Lanza
authors.forename: F
authors.initials: F
authors.lastname: Ciccomascolo
authors.forename: F
authors.initials: F
authors.lastname: Cazzola
authors.forename: A
authors.initials: A
authors.lastname: Di Martino
authors.forename: G
authors.initials: G
authors.lastname: Kirschner
authors.forename: L
authors.initials: L
authors.lastname: Callegaro
authors.forename: L
authors.initials: L
authors.lastname: Chieco-Bianchi
authors.forename: A G
authors.initials: AG
authors.lastname: Siccardi
mesh_terms: D015704:CD4 Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D055598:Chemical Phenomena; D002621:Chemistry; D002772:Cholera Toxin / Q000378:metabolism; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005677:G(M1) Ganglioside / Q000494:pharmacology; D005732:Gangliosides / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation / Q000187:drug effects; D013329:Structure-Activity Relationship
chemical_list: D015704:CD4 Antigens; D005732:Gangliosides; D003208:Concanavalin A; D005677:G(M1) Ganglioside; D002772:Cholera Toxin