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A granuloma is an aggregation of macrophages (along with other cells) that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. [ 1 ]
Epithelioid cell granuloma can be defined as specifically and structurally organized collection of epithelioid cells, macrophages, lymphocytes and dendritic cells. Foreign-body granulomas may be considered an organized collection of macrophages, including mere collections of giant cells surrounding inert substances like suture material – the ...
Giant cells are also known to develop when infections are present. They were first observed as early as the middle of the last century, but it is not fully understood why these reactions occur. In the process of giant cell formation, monocytes or macrophages fuse together, which could cause multiple problems for the immune system. [citation needed]
The main immune cells active in the tissue are macrophages and neutrophils, although other leukocytes are also present. [6] These work to phagocytize old or damaged tissue, and protect the healing tissue from pathogenic infection. This is necessary both to aid the healing process and to protect against invading pathogens, as the wound often ...
Foreign body granuloma formation consists of protein adsorption, macrophages, multinucleated foreign body giant cells (macrophage fusion), fibroblasts, and angiogenesis. It has also been proposed that the mechanical property of the interface between an implant and its surrounding tissues is critical for the host response.
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]
Further proof that these Touton giant cells are histiocytic in origin, meaning they arise from a macrophage-lineage cell, is the fact they react positively to enzymes found in histiocytes such as lysozyme, alpha 1-anti-trypsin and alpha 1-anti-chymotrypsin. Touton giant cells are able to express these proteins which are involved in actions such ...
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.