Immunological responses of healthy elderly population

Area of Science:

• Immunology
• Gerontology

Background:

• Immune system function declines with age, a phenomenon known as immunosenescence.
• Age-associated changes can affect both cellular and humoral immunity.

Purpose of the Study:

• To investigate the effects of aging on immune responses in healthy elderly individuals.
• To compare immune function in healthy elderly, chronically ill elderly, and young controls.
• To examine the relationship between cellular immunity and autoimmunity markers in the elderly.

Main Methods:

• Measured in vitro mitogen responses and delayed hypersensitivity skin tests (cellular immunity).
• Assessed circulating immune complexes (CIC) and autoantibodies (humoral immunity markers).
• Compared data from 279 healthy elderly, 24 chronically ill elderly, and 180 young controls.

Main Results:

• Healthy elderly individuals showed significantly reduced PHA responses and skin test responses compared to young controls.
• Circulating immune complexes and autoantibodies were elevated in healthy elderly individuals versus young controls.
• No significant differences in cellular immunity were observed between healthy and chronically ill elderly subjects, indicating age per se is the main factor.

Conclusions:

• Aging, rather than age-associated diseases, is the primary determinant of diminished cellular immunity in the elderly.
• Despite previous reports, this study did not find a correlation between cellular immune responses and autoimmunity markers (CIC or autoantibodies) in healthy elderly individuals.