title: T-cell priming by dendritic cells in lymph nodes occurs in three distinct phases.
abstract: Primary T-cell responses in lymph nodes (LNs) require contact-dependent information exchange between T cells and dendritic cells (DCs). Because lymphocytes continually enter and leave normal LNs, the resident lymphocyte pool is composed of non-synchronized cells with different dwell times that display heterogeneous behaviour in mouse LNs in vitro. Here we employ two-photon microscopy in vivo to study antigen-presenting DCs and naive T cells whose dwell time in LNs was synchronized. During the first 8 h after entering from the blood, T cells underwent multiple short encounters with DCs, progressively decreased their motility, and upregulated activation markers. During the subsequent 12 h T cells formed long-lasting stable conjugates with DCs and began to secrete interleukin-2 and interferon-gamma. On the second day, coinciding with the onset of proliferation, T cells resumed their rapid migration and short DC contacts. Thus, T-cell priming by DCs occurs in three successive stages: transient serial encounters during the first activation phase are followed by a second phase of stable contacts culminating in cytokine production, which makes a transition into a third phase of high motility and rapid proliferation.
authors.affiliation: The CBR Institute for Biomedical Research, Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Thorsten R
authors.initials: TR
authors.lastname: Mempel
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Henrickson
authors.forename: Ulrich H
authors.initials: UH
authors.lastname: Von Andrian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008198:Lymph Nodes / Q000166:cytology* / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D013997:Time Factors
chemical_list: D007376:Interleukin-2; D007371:Interferon-gamma