Gain and loss of T cell subsets in old age – Age-related reshaping of the T cell repertoire

The immune system is affected by the aging process and undergoes significant agerelatedchanges, termed immunosenescence. Different T cell subsets are affected bythis process. Alterations within the bone marrow and thymus lead to a shift in thecomposition of the T cell repertoire from naïve to antigen-experienced T cells, therebycompromising the diversity of the T cell pool. Additional infection with latent pathogenssuch as Cytomegalovirus aggravates this process. In this review we focus on the majorage-related changes that occur in the naïve and the antigen-experienced T cellpopulation. We discuss the mechanisms responsible for the generation andmaintenance of these subsets and how age-related changes can be delayed orprevented by clinical interventions.