Attenuated interleukin-8/leukocyte immunoresponse in preterm infants compared with term infants hospitalized with respiratory syncytial virus bronchiolitis: a pilot study

Decreased transplacental transfer of antibodies and altered immunoresponsiveness may place preterm (PT) infants at higher risk for serious consequences from respiratory syncytial virus (RSV) bronchiolitis. We hypothesize that among infants hospitalized with RSV bronchiolitis, immune response in PT infants may be different when compared with that of term infants. Nasal-wash samples were collected from 11 PT (<37 weeks of gestation) and 13 term infants (≥37 weeks of gestation) hospitalized with RSV bronchiolitis. Severity of illness (clinical score [CS]), admission peripheral oxygen saturation, and days subjects required supplemental oxygen were compared. Nasal-wash leukocyte count as well as cytokines for interleukin (IL)-8, IL-4, and interferon-γ (IFN-γ) were assayed. No significant differences in CS, admission SaO2, and O2 days were seen between PT and term infants. Nasal-wash leukocyte counts and IL-8 levels were higher in term infants compared with PT and correlated with severity (higher CS) in term (p < 0.05) but not in PT (p > 0.05) infants. IL-4 and IFN-γ levels did not differ between the 2 groups (p > 0.05). PT infants hospitalized with RSV bronchiolitis have lower nasal-wash leukocyte counts and a less robust IL-8 response than term infants, and only in term infants did IL-8 levels correlate with clinical disease severity.