Figure 1. T cell generation and maintenance during aging.
The thymus generates novel naïve T cells early in life, providing a diverse T cell receptor (TCR) repertoire. The maintenance of the naïve T cell pool during adult life is entirely dependent on homeostatic proliferation. In old age, aberrant homeostatic proliferation results in contraction of the T cell pool (especially CD8+ T cells), decrease in TCR repertoire diversity and generation of virtual memory cells (VM).
