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Association between pronounced IgA response in RSV bronchiolitis and development of allergic sensitization
O Strannegård1, J Cello, R Bjarnason
1Department of Clinical Virology, Medical Faculty, University of Göteborg, Sweden.
Insights
Respiratory syncytial virus (RSV) bronchiolitis in infants is linked to a stronger antibody response and a higher risk of developing asthma and allergic sensitization later in life.
Area of Science:
- Pediatric Infectious Diseases
- Immunology
- Allergology
Background:
- Bronchiolitis, a common respiratory infection in infants, is frequently caused by respiratory syncytial virus (RSV).
- The relationship between the infant immune response to RSV and the subsequent development of atopic diseases remains an area of active research.
Purpose of the Study:
- To investigate the association between antibody responses to RSV in infancy and the later development of allergic sensitization and asthma.
- To explore the role of specific antibody types (IgA, IgG) in predicting these outcomes.
Main Methods:
- A cohort study comparing children hospitalized with RSV bronchiolitis to matched controls.
- Measurement of RSV-specific IgA and IgG antibodies at one year of age.
- Follow-up at three years of age to assess allergic sensitization and asthma development.
Main Results:
- Children with RSV bronchiolitis exhibited higher anti-RSV IgA and IgG antibody titers compared to controls.
- Past RSV bronchiolitis was significantly associated with increased allergic sensitization and asthma development by age three.
- Elevated RSV IgA levels at one year predicted allergic sensitization in children with a history of RSV bronchiolitis.
Conclusions:
- RSV bronchiolitis is associated with a robust antibody response, particularly IgA, and may predispose children to atopy.
- The findings support the hypothesis that RSV infection can trigger Th2-mediated immune responses, increasing the risk of allergic diseases.
- RSV bronchiolitis may serve as a significant risk factor or a marker for the later development of atopic disease.
Abstract:
Forty-five children who had been hospitalized with bronchiolitis caused by respiratory syncytial virus (RSV) at a mean age of 4 months, and 90 matched control children, were tested for occurrence of RSV antibodies at one year of age. Of the children who had suffered from bronchiolitis, forty had demonstrable IgG antibodies, whereas the remaining five only had IgA antibodies against RSV. In the control group, 42% were RSV seropositive. The anti-RSV IgA antibody titres tended to be higher in patients with bronchiolitis than in controls and a larger proportion of the seropositive children in the former than in the latter group had demonstrable IgG antibodies. These findings suggest that RSV infections causing bronchiolitis are more often associated with a strong antibody response than are mild cases of the infection. Follow-up of the children at 3 years of age showed that allergic sensitization and development of asthma had occurred much more frequently in children with past RSV bronchiolitis than in controls. Children with past RSV bronchiolitis who later developed allergic sensitization had elevated RSV IgA antibody titres at one year of age more frequently than children with past RSV-bronchiolitis, who were not sensitized (p = 0.015). No significant differences regarding IgG antibody titres were observed. Since IgA, similarly as IgE, antibody formation is strongly Th2 cell dependent, the results are compatible with other findings suggesting that RSV has an unusual propensity to activate the Th2 cell system. This may contribute to the pathological picture of bronchiolitis in small children and at the same time render the infected child predisposed for later development of allergic sensitization. RSV bronchiolitis may thus be an important risk factor for later development of atopic disease although it cannot be excluded that the bronchiolitis simply serves as a marker that predict later development of atopy.