title: Contribution of CD3 gamma to TCR regulation and signaling in human mature T lymphocytes.
abstract: CD3 proteins may have redundant as well as specific contributions to the intracellular propagation and final effector responses of TCR-mediated signals at different checkpoints during T cell differentiation. We report here on the participation of CD3 gamma in the activation and effector function of human mature T lymphocytes at the antigen recognition checkpoint. Following TCR-CD3 engagement of human CD3 gamma-deficient T cell lines, and despite their lower TCR-CD3 surface levels compared to normal controls, mature T cell responses such as protein tyrosine phosphorylation and the regulation of expression of several cell surface molecules, including the TCR-CD3 itself, were either normal or only slightly affected. In contrast, other physiological responses like the specific adhesion and concomitant cell polarization on ICAM-1-coated dishes were selectively defective, and activation-induced cell death was increased. Our data indicate that CD3 gamma contributes essential specialized signaling functions to certain mature T cell responses. Failure to generate appropriate interactions may abort cytoskeleton reorganization and initiate an apoptotic response.
authors.affiliation: Inmunología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Pilar S
authors.initials: PS
authors.lastname: Torres
authors.forename: David A
authors.initials: DA
authors.lastname: Zapata
authors.forename: Alberto
authors.initials: A
authors.lastname: Pacheco-Castro
authors.forename: José L
authors.initials: JL
authors.lastname: Rodríguez-Fernández
authors.forename: Carlos
authors.initials: C
authors.lastname: Cabañas
authors.forename: José R
authors.initials: JR
authors.lastname: Regueiro
mesh_terms: D017209:Apoptosis / Q000502:physiology; D017252:CD3 Complex / Q000276:immunology* / Q000502:physiology; D002460:Cell Line; D015536:Down-Regulation / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D037102:Lectins / Q000502:physiology; D010703:Phorbol Esters / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D017252:CD3 Complex; C452842:CD3 antigen, gamma chain; D037102:Lectins; D010703:Phorbol Esters; D011948:Receptors, Antigen, T-Cell