The immune system in the elderly: III. Innate immunity

Area of Science:

• Immunology
• Gerontology
• Cell Biology

Background:

• Adaptive and innate immunity are crucial for defense against pathogens and cancer.
• Innate immunity involves mechanisms like phagocytosis, natural cytotoxicity, and cytokine signaling.
• Both specific and natural immune mechanisms are interconnected for pathogen defense.

Purpose of the Study:

• To review age-related changes in immune cell activity, including granulocytes and NK cells.
• To examine alterations in adhesion molecule expression and function with aging.
• To discuss changes in cytokine production patterns and their implications.

Main Methods:

• Review of existing literature on immunosenescence.
• Analysis of age-associated changes in neutrophil phagocytosis and respiratory burst.
• Evaluation of NK cell activity in elderly populations, including centenarians.
• Assessment of cell adhesion molecule expression and cytokine profiles in aging.

Main Results:

• Aged neutrophils may show reduced phagocytic capacity and respiratory burst.
• NK cell activity shows varied results, but high NK activity increases with age in healthy individuals.
• Immunosenescence is linked to increased cell adhesion molecule expression.
• Cytokine network changes include a shift from Th1 to Th2 dominance and increased pro-inflammatory cytokines.

Conclusions:

• Innate immunity, particularly NK cell function, may not be severely impaired by aging in healthy individuals.
• Low NK cell activity can predict future illness.
• Age-associated immune changes, like altered cytokine profiles, may contribute to diseases such as atherosclerosis and osteoporosis.