Macrophage
phagocytosis of bacteria, such as H infl uenzae and
S pneumoniae is defective in patients with COPD,66,67 but
the eff ects of COPD on cytokine production are less
clear.68,69 Impaired production of interleukin 8 and
tumour necrosis factor (TNF) α by macrophages in
response to bacterial infection might be related to
exacerbation frequency in COPD.70