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

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 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 - Dec 1 2010


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

ASJC Scopus subject areas

  • Medicine(all)


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