Systemic cytokine profile in children with community-acquired pneumonia

Characterization of the systemic cytokine response in community-acquired pneumonia (CAP) may facilitate our understanding of the host immune response and provide a prognostic as well as diagnostic tool. Systemic cytokine characterization of CAP has been limited largely to a few integral cytokines in adults.

Analyses were performed to investigate whether significant relationships existed between an expanded serum cytokine profile and etiologies, manifestations, and outcomes of pediatric CAP. The serum concentrations of 15 cytokines were investigated in 55 hospitalized children with well-characterized CAP.

Comparison of median cytokine concentrations among patients with CAP caused by Mycoplasma pneumoniae or Chlamydophila pneumoniae, Streptococcus pneumoniae, viruses, mixed infections, or unidentified pathogens revealed significant differences in IFN-alpha, IL-6, IL-17, GM-CSF, and TNF-alpha concentrations. The mixed infections category had significantly elevated concentrations of IFN-alpha, IL-6, GM-CSF, and TNF-alpha. There were significant correlations between concentrations of IL-6 and markers of disease severity (white blood cell band-forms, procalcitonin, and unequivocal consolidation). No single cytokine could reliably differentiate the etiologic cause of pneumonia.

IL-6 is the only one of 15 serum cytokines studied that correlated with indicators of disease severity in childhood CAP. The applicability of cytokine profiles to identify microbiologic etiologies of pneumonia remains to be defined.