Table 1.

Summary of some changes during immunosenescence.

Compartment	Overall changes	References
Adaptive immunity
Decrease in Naïve cell number Decrease in IL-2 production Decrease in lymphoid number Decrease in CD27 expression Decline in antibody diversity (B cells) Increase in memory cell number Increase in regulatory T cell number Increase in CD8+CD28− T cells	Shrinkage of T cell receptor repertoire; Loss of immunological space; Less responsive to immune stimulation/infection and vaccination; Less efficient responses to stress; Decrease ability to cope with environmental challenges, such as reactivation of chronic and new infections; Accumulation of senescent cells in tissue and organs; Reduced proliferative capacity of T cells; Autoimmunity; Immune dysfunctions	(1–4, 24, 29, 30, 32, 33, 36–52)
Innate immunity
Increase in cytokine production Increase in myeloid number Increase in NK cells Increase in the activity of certain signaling pathways, while other pathways are impaired Decrease or no change in phagocytosis Decrease in chemotaxis	Chronic progressive increase in the pro-inflammatory status resulting in inflammaging; Tissue damage and organ dysfunctions; Delayed wound healing; Loss of homeostasis; Modification of interaction with T cells; Predisposition to diseases and risk of frailty	(5, 6, 28, 31, 35, 39, 44, 51, 53–63)

IL, interleukin; Nk cells, Natural killer cells.