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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]
The monocyte is formed in the bone marrow and transported by the blood; it migrates into the tissues, where it transforms into a histiocyte or a macrophage. 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 ...
Cells lining the lymph sinuses, and the capillaries of the adrenals, pituitary and bone marrow also accumulated vital stains, yet to a lower extent. Based on these observations Aschoff in his review concluded that these were the organs housing the cells of the RES, in the narrow sense of the term. [ 4 ]
They are also called pulmonary macrophages, and dust cells. Alveolar macrophages also play a crucial role in immune responses against viral pathogens in the lungs. [25] They secrete cytokines and chemokines, which recruit and activate other immune cells, initiate type I interferon signaling, and inhibit the nuclear export of viral genomes. [25]
The activation of T H 1 and M1 macrophage is a positive feedback loop, with IFN-γ from T H 1 cells upregulating CD40 expression on macrophages; the interaction between CD40 on the macrophages and CD40L on T cells activate macrophages to secrete IL-12; and IL-12 promotes more IFN-γ secretion from T H 1 cells.
CD163 is the high affinity scavenger receptor for the hemoglobin-haptoglobin complex [6] and in the absence of haptoglobin - with lower affinity - for hemoglobin alone. [7] It also is a marker of cells from the monocyte/macrophage lineage. [8] CD163 functions as innate immune sensor for gram-positive and gram-negative bacteria.
The short-term exposure attracts macrophages and neutrophils to the lung with a 4-fold increase in cellularity. [ 4 ] [ 2 ] Short duration also biases polarization towards M1 phenotype. The number of immune cells however will be normalized in 6 months, demonstrating the shift in signaling direction.
A siderophage is a hemosiderin-containing macrophage. Heart failure cells are siderophages generated in the alveoli of the lungs of people with left heart failure or chronic pulmonary edema, when the high pulmonary blood pressure causes red blood cells to pass through the vascular wall. [1] Siderophages are not specific of heart failure.