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Macrophages (/ ˈ m æ k r oʊ f eɪ dʒ /; abbreviated Mφ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that are specific to healthy body cells on their surface.
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.
Another pigment in smoker’s macrophage is hemosiderin which is involved in iron homoeostasis. Hemosiderin-laden pigmented macrophages are yellowish brown and found in the bronchiole and peribronchiolar alveolar space. [9] The presence of these dirty macrophages has been a characteristic of many smoke-related lung diseases. [9] [10]
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 ...
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]
As explained before, they can differentiate into macrophages and dendritic cells, but the different monocyte subpopulations can also exert specific functions on their own. In general, monocytes and their macrophage and dendritic cell progeny serve three main functions in the immune system.
Foamy macrophages are also found in diseases caused by pathogens that persist in the body, such as Chlamydia, Toxoplasma, or Mycobacterium tuberculosis. In tuberculosis (TB), bacterial lipids disable macrophages from pumping out excess LDL, causing them to turn into foam cells around the TB granulomas in the lung. The cholesterol forms a rich ...
The key cellular components of the neuroimmune system are glial cells, including astrocytes, microglia, and oligodendrocytes. [1] [2] [5] Unlike other hematopoietic cells of the peripheral immune system, mast cells naturally occur in the brain where they mediate interactions between gut microbes, the immune system, and the central nervous system as part of the microbiota–gut–brain axis.