The polyfunctionality of memory CD8+ T cells in response to chronic and acute viral infections is not influenced by age (105.49)

Abstract As humans age, they experience a progressive loss of thymic function and a corresponding shift in the nature of the circulating CD8+ T cell population from naïve to memory phenotype. These alterations are believed to result in impaired development of CD8+ T cell immunity in older individuals; however evidence that these global changes impair antigen-specific CD8+ T cell responses in the elderly is lacking. To address this possibility, we studied CD8+ T cell memory development following primary exposure to West Nile virus (WNV) in a cohort of young (<40 yrs), middle-aged (41-60 yrs) and aged (>61 yrs) individuals using polychromatic flow cytometry. Although the aged cohort displayed the previously described alterations in the CD8+ T cell compartment, including a marked loss of naïve CD8+ T cells, accumulation of CD28- and CD57+ T cells, we did not observe any influence of age on either the breadth, magnitude or functionality of antigen-specific CD8+ T cells following WNV, cytomegalovirus (CMV) or Epstein-Barr virus (EBV) peptide stimulation. We did however observe virus-specific CD8+ T cell functional differences between WNV, CMV and EBV. Collectively these data fail to support the hypothesis that immunosenescence leads to defective CD8+ T cell immunity and suggest that it should be possible to develop CD8+ T cell vaccines to protect aged individuals from infections with novel and emerging viruses.