Age-related leukocyte and cytokine patterns in community-acquired bronchopneumonia.

Background: Community-acquired bronchopneumonia in children is frequently accompanied by extreme leukocytosis, whereas in adults with the same diagnosis a high leukocyte count is uncommon. Data regarding differences in the serum levels of inflammatory cytokines between children and adults are limited.

Objectives: To compare leukocyte counts and blood levels of various inflammatory cytokines in children and adults diagnosed with community-acquired bronchopneumonia.

Methods: We prospectively evaluated all pediatric and adult patients admitted for bronchopneumonia based on clinical and chest X-ray findings. Blood was drawn for complete blood count and serum concentration of the following cytokines: granulocyte colony-stimulating factor, interleukins-6, 8 and 10, interferon-gamma, tumor necrosis factor, as well as matrix metalloproteinase-9 and intercellular adhesion molecule-1.

Results: There were 31 children and 32 adults. The patients in both groups had similar parameters of infection severity. None of them required admission to the Intensive Care Unit. Mean (+/- SD) leukocyte counts in the pediatric and adult groups were 21,018/mm3 (+/- 10,420) and 12,628/mm3 (+/- 6735) respectively (P = 0.02). Age was inversely correlated with leukocytes in the pediatric group (P = 0.0001). A significant inverse correlation was also found between age and platelet counts. Although cytokine levels in both groups were not significantly different, age was directly correlated with MMP-9 (P= 0.03), IL-8 (P= 0.03) and G-CSF (P= 0.014).

Conclusions: The immune response in community-acquired bronchopneumonia is, at least partly, age-dependent.