Differences in the kinetics, amplitude, and localization of ERK activation in anergy and priming revealed at the level of individual primary T cells by laser scanning cytometry.
One of the potential mechanisms of peripheral tolerance is the unresponsiveness of T cells to secondary antigenic stimulation as a result of the induction of anergy. It has been widely reported that antigenic unresponsiveness may be due to uncoupling of MAPK signal transduction pathways. However, such signaling defects in anergic T cell populations have been mainly identified using immortalized T cell lines or T cell clones, which do not truly represent primary Ag-specific T cells. We have therefore attempted to quantify signaling events in murine primary Ag-specific T cells on an individual cell basis, using laser-scanning cytometry. We show that there are marked differences in the amplitude and cellular localization of phosphorylated ERK p42/p44 (ERK1/2) signals when naive, primed and anergic T cells are challenged with peptide-pulsed dendritic cells. Primed T cells display more rapid kinetics of phosphorylation and activation of ERK than naive T cells, whereas anergic T cells display a reduced ability to activate ERK1/2 upon challenge. In addition, the low levels of pERK found in anergic T cells are distributed diffusely throughout the cell, whereas in primed T cells, pERK appears to be targeted to the same regions of the cell as the TCR. These data suggest that the different consequences of Ag recognition by T cells are associated with distinctive kinetics, amplitude, and localization of MAPK signaling.
Adams
Claire L
CL
Division of Immunology, Infection and Inflammation, University of Glasgow, Western Infirmary, Glasgow, United Kingdom.
Grierson
Angela M
AM
Mowat
Allan M
AM
Harnett
Margaret M
MM
Garside
Paul
P
D000818:Animals; D017951:Antigen Presentation; D000941:Antigens / Q000276:immunology; D002453:Cell Cycle; D017635:Clonal Anergy / Q000502:physiology*; D003713:Dendritic Cells / Q000276:immunology; D005434:Flow Cytometry / Q000379:methods; D007700:Kinetics; D007834:Lasers; D008213:Lymphocyte Activation; D020935:MAP Kinase Signaling System; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*
D000941:Antigens; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases