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Updated: May 8, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
Early immune profiling reveals distinct inflammatory responses between children and adults few days after primary
Martijn D B Van de Garde1, Alberto Miranda-Bedate1, Nening M Nanlohy1
1Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands.
Insights
Children exhibit a more robust innate immune response to SARS-CoV-2 infection, characterized by higher cytokine secretion and fewer severe symptoms compared to adults. This study highlights key differences in pediatric versus adult immune profiles during COVID-19.
Area of Science:
- Immunology
- Infectious Diseases
- Pediatrics
Background:
- The differential severity of COVID-19 symptoms between children and adults remains unclear.
- Innate immune responses play a critical role in the early stages of pathogen defense.
Purpose of the Study:
- To compare the innate immune responses in children and adults following primary SARS-CoV-2 infection.
- To investigate the relationship between immune profiles, symptom severity, and monocyte phenotypes.
Main Methods:
- Peripheral blood mononuclear cells (PBMCs) and serum were collected from PCR-positive children and adults.
- Cytokine/chemokine levels and monocyte phenotypes were analyzed after in vitro stimulation.
- SARS-CoV-2 Spike-specific IgG levels were measured over time.
Main Results:
- Pediatric PBMCs secreted higher levels of cytokines/chemokines compared to adults post-stimulation.
- Adults showed lower IL-8 levels, while children had higher IL-10 and GM-CSF post-stimulation.
- A lower proportion of non-classical monocytes was observed in adults, correlating with symptom severity.
Conclusions:
- Children demonstrate a stronger inflammatory innate immune profile within the first week of SARS-CoV-2 infection, correlating with milder symptoms.
- Findings elucidate distinct pediatric and adult innate immune responses to SARS-CoV-2.
- This research aids in understanding and improving future prevention strategies for different age groups.
Background:
To date, it is still not clear why during the COVID-19 pandemic children generally developed no or milder symptoms compared to adults. As innate immune responses are crucial in the early defense against pathogens, we aimed at profiling these responses from both adults and children with a primary SARS-CoV-2 infection.
Methods:
In the first months of the pandemic, PBMCs and serum were collected from peripheral blood of adults and children at different time points after testing SARS-CoV-2 PCR positive (PCR+). The levels of SARS-CoV-2 Spike-specific IgG were measured in serum. The cells were cultured for 24 hours in medium only, with heat inactivated SARS-CoV-2 (iSARS-CoV-2) or toll-like receptor (TLR) ligands. The levels of secreted cytokines/chemokines as well as monocyte phenotype were determined.
Results:
Few days after testing PCR+, PBMCs from PCR+ children secreted higher levels of cytokines/chemokines compared to PCR+ adults, after these cells were incubated either in medium only or after stimulation with iSARS-CoV-2 or TLR ligands. Furthermore, PBMCs from children stimulated with iSARS-CoV-2 secreted significantly higher levels of IL-10 and GM-CSF compared to PBMCs from control children. In contrast, PBMCs from the PCR+ adults secreted lower levels of IL-8 compared to adult controls. Phenotypic analysis of monocytes indicates a smaller proportion non-classical monocytes for adults compared to children. The distinct cytokine profiles, symptom severity, and the proportion of non-classical monocytes correlated to each other. The levels of Spike-specific IgG overtime did not significantly differ between children and adults.
Conclusions:
Within the first week after testing PCR+, children showed a stronger inflammatory innate immune profile and experienced less severe symptoms compared to adults. Our data implies correlations between the secretion of cytokines/chemokines, proportion of non-classical monocytes, and symptoms severity. These findings enhance our understanding of the distinct pediatric and adult innate immune profile after SARS-CoV-2 infection and contributes to the knowledge necessary to improve future prevention strategies.
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