09-07-2021-2212 - alveolar macrophage, pulmonary macrophage dust cell repost

An alveolar macrophage, pulmonary macrophage, (or dust cell) is a type of macrophage, a professional phagocyte, found in the airways and at the level of the alveoli in the lungs, but separated from their walls.^[1]

Activity of the alveolar macrophage is relatively high, because they are located at one of the major boundaries between the body and the outside world. They are responsible for removing particles such as dust or microorganisms from the respiratory surfaces.

Alveolar macrophages are frequently seen to contain granules of exogenous material such as particulate carbon that they have picked up from respiratory surfaces. Such black granules may be especially common in smoker's lungs or long-term city dwellers.

The alveolar macrophage is the third cell type in the alveolus, the others are the type I and type II pneumocytes. 

Micrograph showing hemosiderin-laden alveolar macrophages, as seen in a pulmonary haemorrhage. H&E stain.

https://en.wikipedia.org/wiki/Alveolar_macrophage