immunosénescence

Immunosenescence, also referred to as immunosénescence in Spanish, describes the gradual decline of the immune system associated with aging. It involves changes in both innate and adaptive immunity and contributes to higher susceptibility to infection, poorer responses to vaccination, and increased risk of cancer and inflammatory or autoimmune conditions in older adults.

Key hallmarks include thymic involution, which reduces production of naive T cells; accumulation of memory and senescent T cells with limited proliferative capacity; diminished B cell repertoire and antibody responsiveness; and altered function of natural killer cells, dendritic cells and neutrophils. Chronic antigen exposure, particularly cytomegalovirus infection, promotes clonal expansion of senescent T cells. Cellular senescence and the senescence-associated secretory phenotype drive chronic, low-grade inflammation (inflammaging).

Clinically, immunosenescence manifests as increased risk of infections, more severe disease courses, waning vaccine efficacy, higher cancer incidence due to reduced immune surveillance, and a tendency toward dysregulated inflammation or autoimmunity. Laboratory markers include reduced naive T cells, inverted CD4/CD8 ratio, loss of CD28 expression on T cells, telomere shortening and elevated SASP-related cytokines.

Strategies to mitigate immunosenescence focus on lifestyle factors such as regular exercise and adequate nutrition, optimized vaccination approaches for the elderly, and research into interventions that target senescent cells or inflammaging. The phenomenon is an active area of aging research with implications for public health and immune health planning in aging populations.