Healthy Ageing Reflected in Innate and Adaptive Immune Parameters

Changes in immune cell subtypes during ageing

BACKGROUND

The immune system comprises many different types of cells, each with different functions and properties during immune defence. The numbers and types of immune cells in the circulation is highly dynamic and regulated by infections, ageing and certain types of cancers. It is recognised that immune function decreases during ageing, but the biological age at which these functional changes occur is variable, and how ageing affects the different sub-types of lymphocytes, monocytes and NK cells in the circulation is not fully defined.

METHODS

In this study, we recruited 24 healthy volunteers over the age range of 23y to 89y and measured the numbers of different subclasses of circulating cells by immuno-phenotyping and flow cytometry.

RESULTS

We show increased monocyte:lymphocyte ratios in a > 50y cohort and most T cell subsets were decreased, except for CD4+ cells, which were increased in this cohort. In addition, there was NK cell expansion and increased HLA-DR+ T cells, but decreased numbers of classical monocytes and increased numbers of CD4+ monocytes in this >50y cohort.

CONCLUSIONS

These data indicate that healthy ageing is associated with changes in both the major cell groups but also individual subclasses of cells, and these are likely to result from continuous immune challenge and impaired development.

An updated immunosenescence exploration in healthy Chinese donors: circular elevated PD-1 on T cell and increased Ki67 on CD8+ T cell towards aging

Immunosenescence is a process of immune dysfunction that occurs along with aging. Many studies have focused on the changes of different lymphocyte subsets in diseases and immune aging. However, the fluctuation in the number and phenotype of lymphocyte subset caused by aging have not been comprehensively analyzed, especially the effects of new indicators such as PD-1 and Ki67 in peripheral blood have been rarely reported. We further investigated the humoral and cellular immune parameters of 150 healthy donors over 18 years old. Age was associated with decreased CD4+CD45RA+CD62L+ T cells, decreased CD4+CD45RA+CD31+ T cells, and increased memory CD4+ or CD8+ T cells, dominated by male CD8+ T cells. The loss of CD28 expression on T cells and the transverse trend of activated CD38 and HLA-DR were also related to the increased age. In addition, CD8+ T cells in men were more prominent in activation indicators, and the difference between the old and young groups was obvious. CD4+CD25+CD127- T cells percentage tended to decrease with age and did not differ significantly between gender. Interestingly, we found that age was positively associated with PD-1+ T cells and showed significant age-related variability in men. Similarly, the percentage of CD8+ki-67+ also showed an increasing trend, with significant differences between the young group and other elderly groups in males. Our findings can provide immunological clues for future aging research, offering new insights for clinical monitoring and prevention of certain diseases.