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Due to their role in phagocytosis, macrophages are involved in many diseases of the immune system. For example, they participate in the formation of granulomas, inflammatory lesions that may be caused by a large number of diseases. Some disorders, mostly rare, of ineffective phagocytosis and macrophage function have been described, for example ...
Phagocytosis of dead tissue can consequently activate the signaling cascade necessary for regeneration. For instance, the macrophages phagocytosis in liver of dead or necrotic hepatocytes induces Wnt expression, which can influence the proliferation and differentiation of hepatic progenitor cells into liver cells.
The macrophages in the liver activate and release both IL-1 and TNF-alpha. In turn, this activates leukocytes and sinusoidal endothelial cells to express ICAM-1 . This results in tissue damage to the endothelium because of proteases, oxygen radicals, prostanoids and other substances from leukocytes.
The cells are primarily monocytes and macrophages, and they accumulate in lymph nodes and the spleen. The Kupffer cells of the liver and tissue histiocytes are also part of the MPS. The mononuclear phagocyte system and the monocyte macrophage system refer to two different entities, often mistakenly understood as one. [citation needed]
Excessive systemic accumulations of hemosiderin may occur in macrophages in the liver, lungs, spleen, kidneys, lymph nodes, and bone marrow. These accumulations may be caused by excessive red blood cell destruction (haemolysis), excessive iron uptake/hyperferraemia, or decreased iron utilization (e.g., anaemia of copper toxicity) uptake ...
A macrophage's location can determine its size and appearance. Macrophages cause inflammation through the production of interleukin-1, interleukin-6, and TNF-alpha. [75] Macrophages are usually only found in tissue and are rarely seen in blood circulation. The life-span of tissue macrophages has been estimated to range from four to fifteen days ...
These histiocytes are part of the immune system by way of two distinct functions: phagocytosis and antigen presentation. Phagocytosis is the main process of macrophages and antigen presentation the main property of dendritic cells (so called because of their star-like cytoplasmic processes).
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]