Acute and Chronic Disease Reports
Open Access

Pulmonary Macrophages

Macrophages are major sentinels of the lung, functioning as the first line of defense against inhaled pathogens. They are located in the alveoli, interstitium, airways, pleura, and in some species, the vasculature. Displaying unique phenotypes and functions, these pulmonary macrophage subpopulations work together to maintain homeostasis in the lung. They also participate in inflammatory responses to tissue injury and infection. Under normal conditions, the activity of pulmonary macrophages is suppressed in order to limit over reaction to innocuous stimuli. Noxious agents and pathogens can readily overcome this negative regulation. This leads to macrophage activation and the release of proinflammatory/cytotoxic and mitogenic mediators aimed at protecting the host and restoring homeostasis.