Skin T cells maintain their diversity and functionality in the elderly

Area of Science:

• Immunology
• Dermatology
• Gerontology

Background:

• Human resident memory T cells (T_RM) are functionally distinct from circulating T cells.
• Aging impacts immune cell function, particularly in circulating T cells.

Purpose of the Study:

• To investigate the immunologic effects of aging on human skin T cells.
• To compare skin T-cell aging with blood T-cell aging across different ethnicities.

Main Methods:

• Assessed T-cell density, diversity, and function in skin and blood of individuals across a range of ages.
• Analyzed epidermal CD49a⁺ CD8 T_RM frequency and antipathogen responses.

Main Results:

• No decline in skin T-cell density with advancing age was observed.
• Epidermal CD49a⁺ CD8 T_RM frequency increased in elderly individuals.
• Skin T-cell diversity and antipathogen responses were maintained in the elderly, contrasting with declines in blood T cells.

Conclusions:

• Skin T cells maintain density, diversity, and protective cytokine production in elderly individuals.
• Skin resident T cells may serve as a long-lived immune reservoir, crucial for protection in older age.
• These findings highlight the distinct aging patterns of skin-resident versus circulating T cells.