Differential immune responses to acute lower respiratory illness in early life and subsequent development of persistent wheezing and asthma

Background: Recent epidemiologic evidence suggests that 2 wheezing syndromes coexist in early life: transient wheezing, limited to early childhood, and persistent wheezing, which starts in early childhood and persists beyond that age. Objective: Whether the nature of the immune response occurring during acute lower respiratory illnesses (LRIs) in infancy differs between these 2 groups of wheezers has yet to be determined. Methods: We compared total serum IgE levels and peripheral blood eosinophil counts obtained during the acute phase of the first LRI with those obtained during the convalescent phase or with well-baby samples in persistent (n = 49) and transient early wheezers (n = 88), as well as in children who had only nonwheezing LRIs (n = 43) during the first 3 years of life. Results: Total serum IgE levels were significantly higher (P = .008) during the acute phase compared with the convalescent phase of the LRI in persistent wheezers, a response not observed in transient early wheezers (P = .7). Peripheral blood eosinophil counts were significantly reduced during the acute phase of the LRI (P = .009) in transient early wheezers, a response not observed among persistent wheezers (P = .7). Acute responses in children who had nonwheezing LRIs only were similar to those seen in transient early wheezers. Conclusion: Alterations in acute immune response to viral infection may be detected at the time of the first wheezing episode in subjects who will go on to have persistent wheezing symptoms.