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The source for histiocytes is the monocyte/macrophage line. Monocytes (found in the blood) and macrophages (found in tissue) are responsible for phagocytosis (ingestion) of foreign material in the body. Langerhans cells are dendritic cells found in the skin and function by internalizing antigens (foreign particles) and presenting them to T cells.
Histiocytic diseases in dogs are a group of diseases in dogs which may involve the skin, and which can be difficult to differentiate from granulomatous, reactive inflammatory or lymphoproliferative diseases. The clinical presentation and behaviour as well as response to therapy vary greatly among the syndromes.
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.
Three types of Griscelli syndrome are recognised: type 1 has neurologic symptoms and mutations in MYO5A. The prognosis depends on the severity of neurologic manifestations. Type 2 has mutations in RAB27A and haemophagocytic syndrome, with abnormal T-cell and macrophage activation. This type has a grave prognosis if untreated.
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]
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.
Macrophages have been classified as M1 or M2 depending on the adaptive immune response that elicited the phenotype: Th1 or Th2 respectively. [2] [4] [5] The phrase 'alternatively activated macrophage' is used to refer to M2 macrophages. [2] Regulatory macrophages do not fit into the M1/M2 classification system, and they display different ...
Phagocytosis of otherwise-viable pathogens, such as bacteria, can be mediated by neutrophils, monocytes, macrophages, microglia and dendritic cells, and is central to host defence against pathogens. [10] Dendritic cells can phagocytose viable neutrophils, and present antigens derived from bacteria or cancer cell debris previously phagocytosed ...