title: Physiological T cell activation starts and propagates in lipid rafts.
abstract: Lipid rafts are plasma membrane compartments enriched in key signaling molecules. We have previously shown that in T lymphocytes anti-CD3 stimulation is insensitive to cholesterol extraction by methyl-beta-cyclodextrin (MbetaCD), suggesting that anti-CD3 induced signal transduction is independent of raft integrity. Here we show that, in contrast to T cell stimulation by anti-CD3 antibodies, T cell activation by a physiological ligand is mediated by signaling events taking place in lipid raft. Indeed, cholesterol depletion by MbetaCD resulted in reduced T cell activation in response to Epstein Barr Virus (EBV)-transformed B cells pulsed with a bacterial superantigen. Moreover, T cell stimulation by pulsed EBV-B cells, but not by anti-CD3 antibodies, induced recruitment of active Lck in detergent-resistant membranes, where the signal transduction is organized and amplified.
authors.affiliation: Department of Biomedical Sciences, University of Padova, via G Colombo 3, 35121 Padova, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Pizzo
authors.forename: Emanuele
authors.initials: E
authors.lastname: Giurisato
authors.forename: Anna
authors.initials: A
authors.lastname: Bigsten
authors.forename: Maristella
authors.initials: M
authors.lastname: Tassi
authors.forename: Regina
authors.initials: R
authors.lastname: Tavano
authors.forename: Andrey
authors.initials: A
authors.lastname: Shaw
authors.forename: Antonella
authors.initials: A
authors.lastname: Viola
mesh_terms: D000906:Antibodies / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000276:immunology / Q000502:physiology*; D021962:Membrane Microdomains / Q000276:immunology / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*
chemical_list: D000906:Antibodies; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D002784:Cholesterol; D002118:Calcium