Impact of age, sex and CMV-infection on peripheral T cell phenotypes: results from the Berlin BASE-II Study.

Advancing age is characterized by functional and phenotypic alterations in the distribution of circulating T-cell subsets, some of which are exacerbated by a latent infection with the persistent herpesvirus, cytomegalovirus (CMV). The influence of age, sex and CMV-infection on T-cell subpopulations in the peripheral blood remains incompletely understood. Here, T cells from 157 participants of the Berlin Aging Study II (BASE-II) were characterized at 21-34 (n = 59) and 62-85 (n = 98) years of age. We found that the frequency of naïve CD8(+) T cells was significantly lower in the older group than in the young, and was different in men and women. Elderly men had a significantly lower proportion of naïve CD8(+) T cells than younger men, regardless of their CMV-status, but in older women, this was seen only in the CMV-seropositive group. Reciprocally, older men had a higher proportion of late-differentiated, potentially "senescent" CD57(+) T cells. Thus, T-cell senescence may be more pronounced in older men than women. Within the CD4(+) population, in the elderly of both sexes there was a significantly higher proportion of late-differentiated TEMRA cells (T effector memory cells re-expressing CD45RA), but these were present exclusively in CMV-positive subjects. Finally, for the first time, we examined the so-called TSCM cell (T-stem cell-like memory) subpopulations in both CD4(+) and CD8(+) subsets and found that neither CMV-seropositivity nor age or sex affected their frequencies. This study confirms significant cross-sectional age-associated differences of T-cell subset distribution in a representative German urban population and emphasizes the impact of both sex and CMV-infection on T-cell naïve and memory phenotypes, but unaffected frequencies of T-stem cell-like memory cells.