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Updated: Jun 20, 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
Impaired immune response in severe human lower tract respiratory infection by respiratory syncytial virus
Carmen L Larrañaga1, Sandra L Ampuero, Vivian F Luchsinger
1Programa de Virologia, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile. clarrana@med.uchile.cl
Insights
Severe respiratory syncytial virus (RSV) infection in infants is linked to a weakened immune response, including low T cell counts and altered cytokine levels. This suggests an impaired immune system contributes to disease severity.
Area of Science:
- Immunology
- Virology
- Pediatrics
Background:
- Respiratory syncytial virus (RSV) is a primary cause of severe lower respiratory infections in infants.
- Infant immune responses significantly influence RSV disease severity.
- Severe RSV is hypothesized to correlate with impaired immunity, marked by reduced T lymphocytes and plasma cytokines.
Purpose of the Study:
- To investigate in vivo immune responses in infants hospitalized with their first RSV infection.
- To compare immune responses based on clinical severity using cytokine and cellular analysis.
- To identify immune markers associated with severe RSV disease in infants.
Main Methods:
- Analysis of plasma cytokine concentrations in hospitalized infants with RSV.
- Phenotyping of peripheral blood lymphocyte and natural killer (NK) cells.
- Comparison of immune cell counts (CD4+, CD8+, CD19+, NK cells) and cytokine levels (IFN-γ, TNF-α, IL-17, IL-8) between RSV-infected and control infants.
Main Results:
- Infants with RSV showed lower counts of CD4+, CD8+ T cells, CD19+ B cells, and NK cells compared to controls.
- Severe RSV cases exhibited the lowest cell counts, particularly CD8+ T cells and non-active CD94+ NK cells.
- RSV patients had reduced interferon-gamma and tumor necrosis factor-alpha, elevated interleukin-8, and varying interleukin-17 levels, with higher activity of CD94- NK cells.
Conclusions:
- Severe RSV infection in infants is associated with diminished blood proinflammatory cytokine production.
- Low CD8+ T cell counts are a hallmark of severe RSV disease.
- Increased activity of specific NK cell subsets, independent of MHC class Ib, characterizes severe RSV infection.
Background:
Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infection in infants. The immune response plays a leading role in the severity of the disease. We hypothesized that severe RSV disease is associated with an impaired immune response characterized by low circulating T lymphocytes and plasma cytokine concentrations.
Methods:
We evaluate the in vivo immune responses of previously healthy infants with their first proven RSV-acute lower respiratory infection that required hospitalization. According to the clinical severity, defined by using a strict scoring system, the in vivo immune response was compared through the analysis of plasma cytokine values and the phenotyping of peripheral blood lymphocyte and natural killer (NK) cells.
Results:
Absolute blood cell counts of CD4+, CD8+, and CD19+ lymphocytes and NK cells were lower in subjects with RSV than in control infants. Lowest cell counts were observed in more severe RSV-infected infants. Significant low values were obtained in CD8+ lymphocytes (P = 0.03) and nonactive NK cells, that express CD94 antigen (P = 0.046). In contrast, activated NK cells that do not express CD94 molecules were significantly higher in RSV infected infants than in healthy controls (% of cells: P = 0.004). The interferon-gamma and tumor necrosis factor-alpha values in RSV infected patients were lower than in controls subjects. Interleukin-17 cytokine was not detected in healthy infants and the largest concentration was found in moderately ill patients as compared with severe cases (P = 0.033). RSV infection showed significantly higher interleukin-8 chemokine than in control infants (P = 0.024).
Conclusion:
We propose that severe RSV infection in very young infants is associated with poor blood proinflammatory cytokine production, low counts of CD8+ T cells and with a greater activity of a group of NK cells, that are independent of the major histocompatibility complex class Ib recognition system.
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