Senescent phenotypes and telomere lengths of peripheral blood T-cells mobilized by acute exercise in humans

Richard J. Simpson, Cormac Cosgrove, Meng M. Chee, Brian K. McFarlin, David B. Bartlett, Guillaume Spielmann, Daniel P. O'Connor, Hanspeter Pircher, Paul G. Shiels

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Acute bouts of aerobic exercise are known to mobilize antigen-experienced CD8+ T-cells expressing the cell surface marker of senescence, KLRG1, into the blood. It is not known; however, if this is due to a selective mobilization of terminally differentiated T-cells (i.e. KLRG1+/CD28-/CD57+) or a population of effector memory T-cells (i.e. KLRG1+/CD28+/CD57-) that have not reached terminal differentiation. The aim of this study was to further characterize KLRG1+ T-cells mobilized by acute exercise by assessing the co-expression of KLRG1 with CD28 or CD57 and to determine telomere lengths in the CD4+ and CD8+ T-cell subsets. Nine moderately trained male subjects completed an exhaustive treadmill running protocol at 80% . Blood lymphocytes isolated before, immediately after and 1h after exercise were labelled with antibodies against KLRG1, CD28 or CD57, CD4 or CD8 and CD3 for 4-color flow cytometry analysis. Telomere lengths in CD3+, CD4+ and CD8+ T-cells were determined using Q-PCR. The relative proportion of KLRG1+ cells among the CD8+ T-cells increased by 40% immediately after exercise, returning to baseline 1h later. This was due to a mobilization of KLRG1+/CD28- (61% increase), KLRG1+/CD57+ (56% increase) and to a lesser extent, KLRG1+/CD57- cells (24% increase). Telomeres in CD8+ T-cells displayed an increased relative length immediately after exercise, whereas no change occurred for CD4+ or the overall CD3+ T-cells. In conclusion, the increased frequency of KLRG1+/CD8+ T-cells in blood after acute exercise is predominantly due to a selective mobilization of terminally differentiated T-cells. The increased relative telomere length in CD8+ T-cells after exercise might indicate that KLRG1+ cells mobilized by exercise are under stress or aberrant signaling-induced senescence (STASIS). We postulate that a frequent mobilization of these cells by acute exercise might eventually allow naïve T-cells to occupy the "vacant" immune space and increase the naïve T-cell repertoire.

Original languageEnglish (US)
Pages (from-to)40-55
Number of pages16
JournalExercise Immunology Review
StatePublished - 2010
Externally publishedYes


  • CD28
  • CD57
  • Effector memory T-cells
  • Exercise immunology
  • Immunosenescence
  • Killer cell lectin-like receptor G1 (KLRG1)

ASJC Scopus subject areas

  • Immunology


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