γ/δ T cell subsets in human aging using the classical α/β T cell model

Aging is associated with an increased susceptibility to infections and diseases. It has also been associated with reduced functionality and altered distribution of immune cells, especially T cells. Whereas classical / T cells, especially CD8(+) T cells, were shown to be highly susceptible to aging, the effects of viral persistent stimulations on the fate of / T cells are much less documented. Healthy, elderly individuals of Chinese ethnical background were recruited under the aegis of SLAS-II. In this observational study, / T cell populations were characterized by flow cytometry and compared with the / CD4(+) and CD8(+) T cells in elderly and young controls. In our study, we identified a reduced frequency of / T cells but not / T cells with aging. The classical markers of / T cell aging, including CD28, CD27, and CD57, did not prove significant for / T cells. The extreme range of expression of these markers in / T cells was responsible for the lack of relationship between / T cell subsets, CD4/CD8 ratio, and anti-CMV titers that was significant for / T cells and, especially, CD8(+) T cells. Although markers of aging for / T cells are not clearly identified, our data collectively suggest that the presence of CD27 / T cells is associated with markers of / T cell aging.