Background: Few data have been acquired on the predictive value of age-related T-lymphocyte subsets among older individuals. The present study has determined the distribution of T-cell phenotypes and their correlation to 2-year mortality in a cohort of Chinese male seniors.
Methods: A total of 101 asymptomatic elderly individuals with laboratory homeostasis were enrolled at baseline. Three age subgroups were categorized as young (65 - 74 years old), middle (75 - 84 years old), and old (≥ 85 years) for age-related comparison. T-cell subsets in peripheral blood were measured by multi-colored flow cytometry.
Results: At baseline, there was a mild negative correlation by age for total lymphocytes and CD3(+) T-cells. The frequency of CD28 and CD95 demonstrated a "curved" rather than linear tendency by age. At 2-year follow-up, little change of T-cell distribution was found among those who remained alive (as survivors) comparing the data at baseline to the 2-year time point. Immune risk phenotypes were distinctly demonstrated between survivors and non-survivors.
Conclusions: Since few studies have studied on the distribution of T-lymphocyte subsets in an elderly Chinese population, our results have not only provided reference values of T-subsets for aged Chinese men, but confirmed the immune risk phenotypes among elderly Chinese. The inappropriate age-dependent trajectory of CD28(-)/CD8(+) and CD95(-)/CD8(+) by age, which suggested 85 might be an inflexion point of age during T-cell ageing, warrants further exploration of the underlying mechanisms of T-cell ageing.