Macrophages are the predominant defense cell in the normal lung and during conditions associated with chronic inflammation such as COPD. However, the role of the macrophage in the development of COPD has been controversial. Scientific evidence from a variety of sources is emerging that supports a primary role for the macrophage in regulating the inflammatory response and tissue destruction associated with COPD. The role of macrophage proteinases in the development of emphysema, a major component of COPD, will be discussed. Shapiro SD. The macrophage in chronic obstructive pulmonary disease.