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Updated: Feb 24, 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
[Lower lymphocyte response in severe cases of acute bronchiolitis due to respiratory syncytial virus]
José Miguel Ramos-Fernández1, David Moreno-Pérez2, Cristina Antúnez-Fernández1
1Unidad de Gestión Clínica de Pediatría, Grupo de Investigación IBIMA, Hospital Materno-Infantil Regional Universitario de Málaga, Málaga, España.
Insights
Lower lymphocyte counts in infants with respiratory distress indicate a higher risk of severe outcomes, such as pediatric intensive care unit (PICU) admission. This finding aids in predicting the severity of acute bronchiolitis (AB) in hospitalized infants.
Area of Science:
- Pediatrics
- Immunology
- Infectious Diseases
Background:
- Acute bronchiolitis (AB) is a common infant respiratory infection with serious outcomes in 6-16% of hospitalized cases.
- The pathogenesis of AB is linked to T lymphocyte responses.
- Predicting severe outcomes in infants with AB is crucial for timely intervention.
Purpose of the Study:
- To investigate the association between systemic lymphocyte response and the outcome of AB in hospitalized infants.
- To determine if lower lymphocyte counts correlate with a worse prognosis in infants with AB.
Main Methods:
- Retrospective observational study of 252 infants hospitalized with RSV-AB.
- Exclusion of infants with underlying conditions, bacterial superinfections, or prematurity (<32 weeks gestation).
- Analysis of lymphocyte counts within 48 hours of respiratory distress, with logistic regression to identify predictors of PICU admission.
Main Results:
- Infants admitted to the pediatric intensive care unit (PICU) had significantly lower mean lymphocyte counts (4,044±1755/ml) compared to those not admitted (5,035±1786/ml).
- A lymphocyte count below 3700/ml was associated with PICU admission (OR: 3.2).
- This association remained significant in logistic regression analysis, independent of other factors (OR: 3.8).
Conclusions:
- A lymphocyte count below 3700/ml in the early stages of respiratory distress is linked to a worse outcome in infants with RSV-AB.
- This finding applies to previously healthy infants under 12 months with a gestational age greater than 32 weeks.
- Early lymphocyte count can serve as a prognostic marker for severe AB.
Introduction:
Acute bronchiolitis (AB) of the infant has a serious outcome in 6-16% of the hospital admitted cases. Its pathogenesis and evolution is related to the response of the T lymphocytes. The objective of the present study is to determine if the lower systemic lymphocytic response is related to a worse outcome of AB in hospitalised infants.
Patients And Method:
Retrospective observational-analytical study of cases-controls nested in a cohort of patients admitted due to RSV-AB between the period from October 2010 to March 2015. Those with a full blood count in the first 48hours of respiratory distress were included. Infants with underlying disease, bacterial superinfection, and premature infants <32 weeks of gestation were excluded. The main dichotomous variable was PICU admission. Other variables were: gender, age, post-menstrual age, gestational and post-natal tobacco exposure, admission month, type of lactation, and days of onset of respiratory distress. Lymphocyte counts were categorised by quartiles. Bivariate analysis was performed with the main variable and then by logistic regression to analyse confounding factors.
Results:
The study included 252 infants, of whom 6.6% (17) required PICU admission. The difference in mean±SD of lymphocytes for patients admitted to and not admitted to PICU was 4,044±1755 and 5,035±1786, respectively (Student-t test, P<.05). An association was found between PICU admission and lymphocyte count <3700/ml (Chi-squared, P=.019; OR: 3.2) and it was found to be maintained in the logistic regression, regardless of age and all other studied factors (Wald 4.191 P=.041, OR: 3.8).
Conclusions:
A relationship was found between lymphocytosis <3700/ml in the first days of respiratory distress and a worse outcome in previously healthy infants <12 months and gestational age greater than 32 weeks with RSV-AB.
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