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Alveolar macrophage
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The alveolar macrophage is a defense cell that lives inside the lung. Its name comes from the alveoli, the tiny sacs where air and blood exchange gases, and it is also called the dust cell. It belongs to innate immunity, the part of the defenses that acts right away, with no need to have met the intruder before. Down there it is the first line of defense against whatever is breathed in, whether microbes or particles.
The way it works is phagocytosis: it surrounds what it finds and swallows it. It lives deep in the lung and engulfs whatever arrives with the air. It also makes cytokines and chemokines, molecules that serve as messages and calls, and with them it recruits and activates other immune cells.
Unlike the defense cells that come and go through the bloodstream, this one is a resident macrophage. It can form in the lung itself as early as embryonic life and, under stable conditions, stay there for months or years, sustaining its population on site without relying on the monocytes circulating in the blood.
In brief
The alveolar macrophage is a phagocytic cell of innate immunity and the first line of defense inside the lung's alveoli.
It clears debris and microbes from the alveolus by phagocytosis and makes cytokines and chemokines that recruit and activate other immune cells.
It lives deep in the lung and engulfs whatever arrives with the air.
It is a resident macrophage: it can form in the lung during embryonic life, sustain its own population without relying on circulating monocytes, and persist for months or years under stable conditions.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingHistology, Alveolar Macrophages, StatPearlsPublished
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