Discrepancy between cytokine production from peripheral blood mononuclear cells and nasal secretions among infants with acute bronchiolitis

Background Many studies have measured cytokine production derived from peripheral blood mononuclear cells (PBMCs) to evaluate the immune response in acute bronchiolitis (AB), but no previous reports have examined the association between PBMC release of cytokines and concomitant airway immune response. Objective To determine whether interferon-γ (IFN-γ), interleukin 4 (IL-4), and IL-10 levels from PBMCs are associated with concurrent cytokine release in the airways of infants with AB. Methods Infants with acute viral-associated first episode of wheezing who required hospitalization between May and September 2002 were recruited. Nasopharyngeal aspirates (NPAs) and PBMC samples were collected simultaneously. The concentrations of IFN-γ, IL-4, and IL-10 in NPA and PBMC supernatants were determined by enzyme-linked immunosorbent assay. Results Twenty infants with AB were enrolled in the study of whom 17 (85%) had positive NPA immunofluorescence results for viral detection and respiratory syncytial virus. Median total cell count and viability from NPA samples were 2.2 × 10 6 cells/mL (SD, 1.7 cells/mL) and 92% (SD, 6.0%), respectively. There was a significant correlation between IL-4 levels from NPA and PBMC samples ( r = 0.5, P = .02); however, we did not find an association between IFN-γ and IL-10 levels. Conclusions Cytokines produced by in vitro PBMCs may not necessarily reflect the concurrent cytokine pattern production at the mucosal surface in the respiratory tract of infants with AB. Further studies are required to determine whether peripheral blood is a reliable sample for airway inflammation evaluation and to explain the discrepancies of cytokine productions found in this study.