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Cellular immunity is activated and a TH-2 response is associated with early wheezing in infants after bronchiolitis
P M Renzi1, J P Turgeon, J P Yang
1Sainte-Justine, Research Center, University of Montreal, Quebec, Canada.
Insights
Bronchiolitis can lead to immune system changes. Early wheezing in infants is linked to a specific immune response, suggesting a potential pathway for recurrent respiratory issues.
Area of Science:
- Pediatric immunology
- Respiratory medicine
- Cellular immunology
Background:
- Bronchiolitis is a common respiratory infection in infants.
- Cellular immunity plays a crucial role in post-viral responses.
- The link between bronchiolitis, immune responses, and subsequent wheezing requires further investigation.
Purpose of the Study:
- To investigate cellular immunity abnormalities in infants following bronchiolitis.
- To determine if these abnormalities correlate with early wheezing episodes.
Main Methods:
- Prospective study of 26 infants hospitalized for bronchiolitis.
- Blood analysis for immune cell counts, activation markers (CD4+, CD8+, CD25+, CD23+), and cytokine levels (interferon gamma, IL-4).
- Parental logs tracked wheezing episodes post-discharge.
Main Results:
- Infants showed increased eosinophils and activated lymphocytes (CD4+, CD25+, CD23+) 5 months post-bronchiolitis.
- Infants experiencing wheezing produced more IL-4 in response to allergens.
- Higher wheezing frequency correlated with increased eosinophils and basophils.
Conclusions:
- Bronchiolitis is associated with cellular immune activation.
- Early wheezing in infants post-bronchiolitis is linked to a T-helper 2 (TH-2) immune response.
Objective:
To determine whether abnormalities of cellular immunity are present and linked to early wheezing after bronchiolitis.
Methods:
We prospectively studied 26 infants hospitalized for a first episode of bronchiolitis and without any prior immune, cardiac, or respiratory disease. Blood was obtained at the time of enrollment and 5 months later for the assessment of the total cellular and differential counts, CD4+ (helper) and CD8+ (suppressor/cytotoxic) lymphocytes, and the activation markers CD23 (low-affinity immunoglobulin E receptor) and CD25 (interleukin-2 (IL-2) receptor). The cytokines interferon gamma (T-helper (TH) type-1 cytokine) and IL-4 (TH-2) were measured in plasma and in vitro after stimulation with IL-2 or with the house-dust mite (Dermatophagoides farinae) antigen. A daily log of episodes of wheezing was kept by parents after discharge.
Results:
We found an increase in blood eosinophils, an increased percentage of CD4+, CD25+, and CD23+ lymphocytes in subjects at 5 months compared with the time of bronchiolitis and with healthy subjects of the same age (p < 0.05). Plasma IL-4 levels, although not different from those of healthy subjects, also increased significantly. Peripheral blood lymphocytes from infants who wheezed produced more IL-4 in vitro, 5 months after bronchiolitis, in response to D. farinae antigen. In babies who wheezed, a positive correlation was found between the total number of days that wheezing occurred and the blood eosinophil count. Babies who wheezed more often (> 20 days) had more peripheral blood basophils and eosinophils, and peripheral blood lymphocytes obtained from these subjects at the time of bronchiolitis produced less interferon gamma on stimulation with IL-2.
Conclusions:
Bronchiolitis is followed by activation of cellular immunity, and early wheezing in infants is associated with a TH-2 response.