Local inflammatory responses in community-acquired pneumonia (CAP) remain insufficiently elucidated, especially in patients with nonsevere CAP. In this study we determined local and systemic cytokine responses in CAP patients and correlated these with disease severity and other clinical parameters. Levels of interleukin (IL)-6, IL-8, IL-10, IL-1β, tumour necrosis factor-α, interferon (IFN)-γ, IL-22, IL-17A and IL-4 were determined in bronchoalveolar lavage fluid and serum of 20 CAP patients upon admission and 10 healthy individuals. Systemic cytokine levels were also measured on days 7 and 30. In bronchoalveolar lavage fluid of CAP patients, levels of IL-6, IL-8 and IFN-γ were significantly increased compared with healthy individuals, but no correlations with disease severity were found. Systemic levels of IL-6, IL-10 and IFN-γ were significantly higher in severe CAP patients than in nonsevere CAP patients and healthy individuals. Moreover, these cytokines showed a significant correlation with the pneumonia severity index. In the total group of CAP patients, systemic IL-8 and IL-22 levels were also increased compared with healthy individuals. We therefore conclude that IL-6, IL-10 and IFN-γ are important cytokines in CAP, although differences in disease severity upon admission are only reflected by systemic levels of these cytokines.
Keywords: Bronchoalveolar lavage; community-acquired pneumonia; cytokines; inflammation.