Methods: One hundred and seven children under 3 years of age who were admitted with RSV-LRI (bronchiolitis and/or pneumonia) were enrolled. The patients were divided into 2 groups according to their total serum IgE levels on admission: High IgE group (N=39) and normal IgE group (N=68). High IgE levels were defined as values higher than 2 standard deviations (SDs) from the age-matched mean value. The medical records of the patients were investigated to determine if there was any difference in demographic characteristics, clinical and laboratory findings during admission, and recurrence of wheezing within 1 year after discharge between these 2 groups. Among 107 patients, 76 had LRIs for the first time in their lives, from whom we re-analyzed the data in relation to IgE levels. Additionally, difference between children with isolated RSV infection (N=107) and mixed infection with other viruses (N=88) was examined.
Results: Median age was 15 months in high IgE group and 5.6 months in normal IgE group (P<0.001). Male preponderance was observed only in the high IgE group (P<0.01). The frequency and duration of fever, severity of symptoms, and concurrence of respiratory difficulty were significantly higher in high than normal IgE group (P<0.05). There was no difference in admission days and parental allergic diseases. Nearly same findings were observed in re-analysis of data from the patients with the 1st RSV-LRIs, but recurrence of wheezing after discharge was significantly higher in high IgE group (P<0.05). The children with isolated RSV infection showed more frequent and prolonged wheezing than those with mixed infection.
Conclusions: In our study, the children who presented with high serum IgE levels during RSV-LRI had more severe symptoms comparing with those with normal IgE levels. Our results suggest that increased Th2 immune response induced by acute RSV infection might be associated with severe clinical presentation of LRI.