Related Experiment Video
Updated: Sep 8, 2026
Image-based Flow Cytometry Technique to Evaluate Changes in Granulocyte Function In Vitro
Published on: December 26, 2014
Age differences in phagocytosis by polymorphonuclear leukocytes measured by flow cytometry
Abstract:
Elderly persons have increased morbidity and mortality due to bacterial infections. Since the polymorphonuclear leukocyte (PMN) is a major defense against bacterial infection, we utilized fluorescent microspheres and flow cytometry to examine phagocytosis by PMNs from 55 young and middle-aged adults (mean age 41.5 yrs) and two groups of elderly subjects: one group of 35 healthy individuals (mean age 74.1 years) living at home, and a second group of 11 residents (mean age 83.1 years) with severe mental and physical disabilities, living in a domiciliary care facility. We determined the percent phagocytic PMNs, the number of microspheres per PMN, and the number of microspheres per 100 PMNs. The mean number of microspheres per phagocytic PMN was similar for all groups. Statistically significant differences were found between the young and middle-aged group and the healthy or ill elderly groups for the percent phagocytic PMNs (75.3% vs 51.5% and 43.8%), and the number of microspheres per 100 phagocytic PMNs (197.3 vs 131.4 and 103.2). There were no significant differences in these parameters between healthy and debilitated elderly subjects. These data document that there is an age-related increase in representation of a population of PMNs which have a defect in phagocytic ability.
Insights
Elderly individuals exhibit reduced phagocytic activity in polymorphonuclear leukocytes (PMNs), increasing bacterial infection risk. This age-related decline in PMN function impacts immune defense in older adults.
Area of Science:
- Immunology
- Gerontology
- Cell Biology
Background:
- Elderly populations face higher risks of bacterial infections, linked to compromised immune function.
- Polymorphonuclear leukocytes (PMNs) are critical for combating bacterial pathogens.
Purpose of the Study:
- To investigate age-related changes in PMN phagocytosis.
- To compare phagocytic capacity in young, healthy elderly, and debilitated elderly individuals.
Main Methods:
- Utilized fluorescent microspheres and flow cytometry to assess PMN phagocytosis.
- Quantified percent phagocytic PMNs, microspheres per PMN, and microspheres per 100 PMNs.
- Included young adults, healthy elderly, and elderly residents of a care facility.
Main Results:
- Phagocytic PMN percentage and microspheres per 100 PMNs were significantly lower in elderly groups compared to younger adults.
- No significant differences were observed between healthy and debilitated elderly subjects.
- The number of microspheres per phagocytic PMN remained consistent across all age groups.
Conclusions:
- An age-related increase in PMNs with defective phagocytic ability was identified.
- This impaired PMN function contributes to increased susceptibility to bacterial infections in the elderly.
- Immune senescence affects PMN phagocytosis, regardless of overall health status in elderly individuals.
