[Cytokines and surfactant as a factor of onset and progression of COPD]

Cigarette smoking is a most important factor of COPD. IL-8 is elevated by cigarette smoking and increases the number of neutrophils in the lung. Surfactant is a complex mixture of phospholipids (PL) and proteins (SP). Both PL and SPs (SP-A and SP-D) decrease in bronchoalveolar lavage fluid in smokers. Decrease of PL enhances injury by elastase secreted from neutrophils and induces collapse of bronchioles, and decrease of SP-A and SP-D attenuate the defense against microbial agents in peripheral airways. Surfactant is thereby associated with COPD. However, little is known about the interaction, which induces COPD, between cytokines and surfactant. Further investigations are needed to clarify the mechanism on onset of COPD.