Age related human T cell subset evolution and senescence

T cells are fundamental effector cells against viruses and cancers that can be divided into different subsets based on their long-term immune protection and immediate immune response effects. The percentage and absolute number of these subsets change with ageing, which leads to a reduced immune response in older individuals. Stem cell memory T cells (T(SCM)) represent a small population of memory T cells with enhanced proliferation and differentiation properties that are endowed with high potential for maintaining T cell homeostasis. However, whether these cells change with ageing and gender remains unknown. Here, we assayed the distribution of T(SCM) and other T cell subsets in peripheral blood from 92 healthy subjects (44 females and 48 males) ranging from 3 to 88 years old by flow cytometry. We found that CD4+ and CD8+ T(SCM) in the circulation have relatively stable frequencies, and the absolute number of CD8+ T(SCM) decreased with age; however, the ratio of T(SCM) to the CD4+ or CD8+ naïve population increased with age. Unlike the obvious changes in other T cell subsets with age and gender, the stable level of T(SCM) in peripheral blood may support their capacity for sustaining long-term immunological memory, while their importance may increase together with ageing. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12979-019-0165-8) contains supplementary material, which is available to authorized users.