title: CD4 T cells integrate signals delivered during successive DC encounters in vivo.
abstract: The cellular mode of T cell priming in vivo remains to be characterized fully. We investigated the fate of T cell-dendritic cell (DC) interactions in the late phase of T cell activation in the lymph node. In general, CD4 T cells detach from DCs before undergoing cell division. Using a new approach to track the history of antigen (Ag)-recognition events, we demonstrated that activated/divided T cells reengage different DCs in an Ag-specific manner. Two-photon imaging of intact lymph nodes suggested that T cells could establish prolonged interactions with DCs at multiple stages during the activation process. Importantly, signals that are delivered during subsequent DC contacts are integrated by the T cell and promote sustained IL-2Ralpha expression and IFN-gamma production. Thus, repeated encounters with Ag-bearing DCs can occur in vivo and modulate CD4 T cell differentiation programs.
authors.affiliation: G5 Dynamiques des Réponses Immunes, INSERM 668, Département d'Immunologie, Institut Pasteur, Paris, France.
authors.forename: Susanna
authors.initials: S
authors.lastname: Celli
authors.forename: Zacarias
authors.initials: Z
authors.lastname: Garcia
authors.forename: Philippe
authors.initials: P
authors.lastname: Bousso
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D002450:Cell Communication / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D003713:Dendritic Cells / Q000276:immunology / Q000502:physiology*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D015398:Signal Transduction / Q000276:immunology*
chemical_list: D000941:Antigens; D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse