ABSTRACT
BACKGROUND: Virus-associated febrile lower respiratory tract infections (fLRIs) during infancy have been identified as risk factors for persistent wheeze development. We hypothesized that variations in innate immune defense capacity during this period, as exemplified by production of type 1 and 3 interferons (T1/3IFNs), might be an underlying determinant of risk. OBJECTIVE: We sought to investigate relationships between postnatal development of innate interferon response capacity and susceptibility to early infections and persistent wheeze. METHODS: We studied a subset of subjects from a birth cohort at high risk for asthma/allergy and determined the capacity of cord blood cells (n = 151) to produce any of a panel of 17 T1/3IFNs in response to the viral mimic polyinosinic-polycytidylic acid using a sensitive PCR assay. We investigated relationships between neonatal interferon responses and lower respiratory tract infection history during infancy, wheezing history to 5 age years, and ensuing maturation of innate immune capacity by age 4 years (n = 160) and 10 years (n = 125). RESULTS: Although cohort subjects produced an average of 2.6 ± 0.3 of the 17 innate interferons tested at birth, 24% showed no T1/3IFN production. This nonproducer subgroup showed increased risk for infant fLRIs (odds ratio, 2.62; 95% CI, 1.14-6.06; P = .024) and persistent wheeze (odds ratio, 4.24; 95% CI, 1.60-11.24; P = .004) at age 5 years relative to those producing 1 or more T1/3IFNs, whereas risk for infant wheezy lower respiratory tract infections or "transient early wheeze" was unaffected. Moreover, infants who experienced fLRIs subsequently demonstrated accelerated development of T1/3IFN response capacity between 1 and 4 years of age. CONCLUSIONS: T1/3IFN response capacity appears strongly developmentally constrained at birth. Infants in whom this negative regulation is strongest manifest increased risk for severe respiratory tract infections during infancy and subsequent persistent wheeze.
