Elderly people with prior COVID-19 showed persistent apoptotic changes in peripheral immune cells at least six months after infection.
Evidence
A 2025 cross-sectional flow-cytometry study compared PBMC markers in adults older than 65 with documented prior COVID-19 against controls.
Caveat
The design links post-COVID history to immune-cell apoptosis but cannot prove causality or separate effects of initial illness severity and time since infection.
Simplified
BACKGROUND AND AIM: The COVID-19 pandemic has left a lasting imprint on immune function, particularly in the elderly-a population already vulnerable to . While acute and long-COVID immune responses have been widely studied, the long-term apoptotic behavior of peripheral blood mononuclear cells (PBMCs) remains underexplored. This study aims to investigate the legacy of SARS-CoV-2 on PBMC in elderly individuals during the post-COVID era, shedding light on potential persistent immune dysregulation.
MATERIALS AND METHODS: In this cross-sectional study, PBMCs were isolated from peripheral blood samples of elderly individuals (> 65 years old) with a documented history of COVID-19 infection at least six months prior. Using multiparametric flow cytometry, we quantified early and late apoptosis markers (Annexin V/PI), mitochondrial membrane potential disruption (ΔΨm), and expression of pro-apoptotic (Bax, Caspase-3) and anti-apoptotic (Bcl-2) proteins. Statistical analyses were performed to assess intergroup differences and correlations with clinical history. This study was conducted in 2025.
RESULTS: Elderly post-COVID individuals exhibited a significantly elevated proportion of apoptotic PBMCs compared to controls (p < 0.01), particularly within the CD4 + and CD8 + T-cell subsets. Mitochondrial depolarization and increased Bax/Bcl-2 ratios indicated a shift toward intrinsic apoptotic pathways. Caspase-3 activation was also heightened in the post-COVID group. Notably, apoptotic burden correlated with time since infection and severity of initial illness.
DISCUSSION: Our findings suggest a prolonged apoptotic signature in the immune cells of elderly individuals following recovery from COVID-19. These alterations may reflect a sustained immune exhaustion or maladaptive remodeling of lymphocyte populations, potentially contributing to impaired immunosurveillance and increased vulnerability to secondary infections or chronic inflammatory conditions.
CONCLUSION: COVID-19 may cast a long immunological shadow in the elderly, with persistent PBMC apoptosis representing a novel facet of post-viral immune dysregulation. Flow cytometry reveals a unique apoptotic phenotype that could serve as a biomarker for long-term immune health and guide post-pandemic clinical management strategies for aging populations.
Key numbers
p < 0.01
Increase in
Proportion of apoptotic in elderly post-COVID vs. controls
2.4 ± 0.5
Mitochondrial Depolarization
in post-COVID vs. controls
1,825 ± 240
/ Ratio Increase
expression in post-COVID vs. controls
Full Text
We can’t show the full text here under this license.
