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Micrograph showing hemosiderin-laden alveolar macrophages, as seen in a pulmonary hemorrhage. H&E stain. 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]
Alveolar macrophages (dust cells) engulf the red blood cells, and become engorged with brownish hemosiderin. In chronic pulmonary edema, alveolar septa become thick and fibrous, again increasing pressure on alveolar capillaries and resulting in leakage of red blood cells which undergo phagocytosis by alveolar macrophages .
Macrophages are diffusely scattered in the connective tissue and in liver (Kupffer cells), spleen and lymph nodes (sinus histiocytes), lungs (alveolar macrophages), and central nervous system (microglia). The half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years.
Lipid-laden alveolar macrophages, also known as pulmonary foam cells, [2] are cells found in bronchoalveolar lavage (BAL) specimens that consist of macrophages containing deposits of lipids (fats). [3] The lipid content of the macrophages can be demonstrated using a lipid targeting stain like Oil Red O or Nile red.
Through the release of Interleukin 4 (IL-4) and Interleukin 13 (IL-13) by TH2, or T helper cells, and mast cells, these macrophages can fuse to form foreign body giant cells. [1] [4] The macrophages are initially attracted to the injury/infection site through a variety of chemoattractants like growth factors, platelet factors, and interleukins. [4]
Pathology: The lung vessels are congested with blood and this leads to pulmonary edema when plasma escapes in alveolar spaces. Rupture of congested capillaries leads to release of hemosiderin from damaged red blood cells. When alveolar macrophages engulf hemosiderin they are called heart failure cells.
Macrophages are found throughout the body in almost all tissues and organs (e.g., microglial cells in the brain and alveolar macrophages in the lungs), where they silently lie in wait. A macrophage's location can determine its size and appearance. Macrophages cause inflammation through the production of interleukin-1, interleukin-6, and TNF ...
Smoker's macrophages are alveolar macrophages whose characteristics, including appearance, cellularity, phenotypes, immune response, and other functions, have been affected upon the exposure to cigarettes. [1] These altered immune cells are derived from several signaling pathways and are able to induce numerous respiratory diseases.