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Influence of age on polymorphonuclear leukocytes in vitro: phagocytic activity in healthy human subjects
Abstract:
Polymorphonuclear leukocytes (PMNs) represent an important defensive mechanism against infectious agents. Some of their functions are impaired in old people, with a decreased effectiveness of nonspecific immunity. In vitro PMN phagocytic activity was studied with different techniques on 74 healthy subjects (20-82.5 years; 40 males, 34 females). Serum-mediated ingestion resulted to be impaired with age with a lower ratio of active PMNs and a lower activity of phagocytosing cells. The behavior of these parameters was age-related, without significant difference between males and females; the decline was found to be a continuous phenomenon with no threshold age. Serum-independent ingestion had very low values and was not impaired with aging. The present data can represent a further explanation for the finding of a higher incidence and mortality of bacterial diseases in elderly population.
Insights
Immune function declines with age, as polymorphonuclear leukocytes (PMNs) show reduced phagocytic activity. This age-related decline in immune cells may explain higher infection rates in older adults.
Area of Science:
- Immunology
- Gerontology
- Cellular Biology
Background:
- Polymorphonuclear leukocytes (PMNs) are crucial for innate immunity against pathogens.
- Immune function, particularly nonspecific immunity, often diminishes with advanced age.
- Elderly populations exhibit increased susceptibility and mortality from bacterial infections.
Purpose of the Study:
- To investigate the age-related changes in in vitro phagocytic activity of PMNs.
- To determine if gender influences the age-related decline in PMN function.
- To explore the impact of aging on serum-mediated versus serum-independent PMN ingestion.
Main Methods:
- Studied in vitro phagocytic activity of PMNs from 74 healthy individuals aged 20-82.5 years.
- Utilized various techniques to assess PMN ingestion capabilities.
- Analyzed data for age- and gender-related differences in immune cell function.
Main Results:
- Serum-mediated phagocytosis by PMNs significantly declines with age.
- A lower proportion of active PMNs and reduced phagocytic capacity were observed in older subjects.
- This decline was continuous across age groups, with no specific threshold, and was not gender-dependent.
- Serum-independent ingestion showed minimal activity and was unaffected by aging.
Conclusions:
- Age-related impairment in PMN phagocytic function, particularly serum-mediated, contributes to increased vulnerability to infections in the elderly.
- The findings provide a cellular mechanism explaining higher incidence and mortality of bacterial diseases in older adults.
- Immune surveillance and defense mechanisms are compromised during the aging process.