Background: In association with respiratory tract infections, infants may have episodes of wheezing, which represent the onset of asthma in some of them. Activated eosinophils play a central part in asthmatic inflammation.
Objective: We investigated whether, in infants experiencing their first episode of wheezing, eosinophil activation is present and can predict the development of asthma.
Methods: In a prospective trial, eosinophil activation was measured by eosinophil cationic protein (ECP) concentrations in serum from 33 nonatopic infants with their first episode of wheezing, 15 nonatopic infants with upper respiratory tract infection without wheezing, and 18 healthy nonatopic infants. One year later, the children were re-evaluated for a diagnosis of infantile asthma.
Results: Wheezing infants had higher median serum ECP levels (13.4 micrograms/L) than children with nonwheezy respiratory tract infection (7.6 micrograms/L, p < 0.005) or healthy subjects (7.1 micrograms/L, p < 0.005). In addition, wheezing infants (n = 13) with serum ECP concentrations greater than 20 micrograms/L were more likely to have asthma within 1 year than patients with ECP levels less than 20 micrograms/L (odds ratio = 12.4; confidence interval, 4.6-33.5).
Conclusion: Eosinophil activation measured by serum ECP is present in infants with their first episode of wheezing illness, especially in those infants in whom asthma subsequently develops within 1 year. These data may indicate a predictive value of serum ECP measurements in children with wheezing to identify those patients in whom infantile asthma is developing. These findings probably also indicate that serum ECP may be used to identify the children who need early antiinflammatory treatment.