Differences in the kinetics, amplitude, and localisation of ERK activation in anergy and priming revealed at the level of individual primary T cells by laser scanning cytometry

Garside, Paul and Grierson, Angela M. and Harnett, Margaret M. and Adams, Claire L. and Mowat, Allan M. (2004) Differences in the kinetics, amplitude, and localisation of ERK activation in anergy and priming revealed at the level of individual primary T cells by laser scanning cytometry. Journal of Immunology, 173 (3). pp. 1579-1586. ISSN 0022-1767

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Abstract

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.