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A dendritic cell (DC) is an antigen-presenting cell of the mammalian immune system. A DC's main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and adaptive immune systems.
Macrophages 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. This process is called phagocytosis, which acts to defend the host against infection and injury.
Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek phagein, "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek kutos, "hollow vessel". They are essential for fighting infections and for subsequent immunity. Phagocytes are important throughout the animal kingdom and are highly developed within vertebrates. One litre of human blood contains about six billion phagocytes. They were discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae. Mechnikov was awarded the 1908 Nobel Prize in Physiology or Medicine for his discovery. Phagocytes occur in many species; some amoebae behave like macrophage phagocytes, which suggests that phagocytes appeared early in the evolution of life.
Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and monocyte-derived dendritic cells. As a part of the vertebrate innate immune system monocytes also influence adaptive immune responses and exert tissue repair functions. There are at least three subclasses of monocytes in human blood based on their phenotypic receptors.
In immunology, the mononuclear phagocyte system or mononuclear phagocytic system (MPS) also known as the macrophage system is a part of the immune system that consists of the phagocytic cells located in reticular connective tissue. 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.
Kupffer cells, also known as stellate macrophages and Kupffer–Browicz cells, are specialized cells localized in the liver within the lumen of the liver sinusoids and are adhesive to their endothelial cells which make up the blood vessel walls. Kupffer cells comprise the largest population of tissue-resident macrophages in the body. Gut bacteria, bacterial endotoxins, and microbial debris transported to the liver from the gastrointestinal tract via the portal vein will first come in contact with Kupffer cells, the first immune cells in the liver. It is because of this that any change to Kupffer cell functions can be connected to various liver diseases such as alcoholic liver disease, viral hepatitis, intrahepatic cholestasis, steatohepatitis, activation or rejection of the liver during liver transplantation and liver fibrosis. They form part of the mononuclear phagocyte system.
Langerhans cell histiocytosis (LCH) is an abnormal clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes.
The innate immune system or nonspecific immune system is one of the two main immunity strategies in vertebrates. The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, prokaryotes, and invertebrates.
Malignant histiocytosis is a rare hereditary disease found in the Bernese Mountain Dog and humans, characterized by histiocytic infiltration of the lungs and lymph nodes. The liver, spleen, and central nervous system can also be affected. Histiocytes are a component of the immune system that proliferate abnormally in this disease. In addition to its importance in veterinary medicine, the condition is also important in human pathology.
A histiocytoma in the dog is a benign tumor. It is an abnormal growth in the skin of histiocytes (histiocytosis), a cell that is part of the immune system. A similar disease in humans, Hashimoto-Pritzker disease, is also a Langerhans cell histiocytosis. Dog breeds that may be more at risk for this tumor include Bulldogs, American Pit Bull Terriers, American Staffordshire Terriers, Scottish Terriers, Greyhounds, Boxers, and Boston Terriers. They also rarely occur in goats and cattle.
Monoblasts are the committed progenitor cells that differentiated from a committed macrophage or dendritic cell precursor (MDP) in the process of hematopoiesis. They are the first developmental stage in the monocyte series leading to a macrophage. Their myeloid cell fate is induced by the concentration of cytokines they are surrounded by during development. These cytokines induce the activation of transcription factors which push completion of the monoblast's myeloid cell fate. Monoblasts are normally found in bone marrow and do not appear in the normal peripheral blood. They mature into monocytes which, in turn, develop into macrophages. They then are seen as macrophages in the normal peripheral blood and many different tissues of the body. Macrophages can produce a variety of effector molecules that initiate local, systemic inflammatory responses. These monoblast differentiated cells are equipped to fight off foreign invaders using pattern recognition receptors to detect antigen as part of the innate immune response.
In anatomy and histology, the term wandering cell is used to describe cells that are found in connective tissue, but are not fixed in place. This term is used occasionally and usually refers to blood leukocytes in particular mononuclear phagocytes. Frequently, the term refers to circulating macrophages and has been used also for stationary macrophages fixed in tissues (histiocytes), which are sometimes referred to as "resting wandering cells".
CD68 is a protein highly expressed by cells in the monocyte lineage, by circulating macrophages, and by tissue macrophages.
Epithelioid cells are derivatives of activated macrophages resembling epithelial cells.
A non-specific immune cell is an immune cell that responds to many antigens, not just one antigen. Non-specific immune cells function in the first line of defense against infection or injury. The innate immune system is always present at the site of infection and ready to fight the bacteria; it can also be referred to as the "natural" immune system. The cells of the innate immune system do not have specific responses and respond to each foreign invader using the same mechanism.
White blood cells, also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. White blood cells include three main subtypes: granulocytes, lymphocytes and monocytes.
Zanvil Alexander Cohn was a cell biologist and immunologist who upon his death was described by The New York Times as being "in the forefront of current studies of the body's defenses against infection.", professor at Rockefeller University. There Cohn had been the Henry G. Kunkel Professor for seven years. Cohn was senior physician at the university as well as vice president for medical affairs. Until two years before his death, he also served as principal investigator of the Irvington Institute for Medical Research. Although Cohn never won the Nobel Prize, Ralph M. Steinman, with whom he ran a laboratory at Rockefeller University for many years, was named to win the 2011 Nobel Prize in Physiology or Medicine for the work on dendritic cells done in their lab, eighteen years after Cohn's death.
Miram Merad is a French-Algerian professor in Cancer immunology and the Director of the Marc and Jennifer Lipschultz Precision Immunology Institute (PrIISM) at the Icahn School of Medicine at Mount Sinai (ISMMS) in New York, NY. She is the corecipient of the 2018 William B. Coley Award for Distinguished Research in Basic Immunology and a member of the United States National Academy of Sciences and the National Academy of Medicine.
Crystal-storing histiocytosis is a form of histiocytosis that mostly occurs in people with monoclonal gammopathies. Histiocytosis is an excessive number of histiocytes. In the vast majority of crystal-storing histiocytosis cases, immunoglobulins accumulate within the cytoplasm of histiocytes; in rare cases clofazimine, cystine, silica, or Charcot–Leyden crystals may be found in the histiocytes instead. Non-immunoglobulin crystal-storing histiocytosis is mostly associated with non-malignant disorders, such as chronic inflammation or autoimmune abnormality conditions such as rheumatoid arthritis, Crohn's disease, or Helicobacter pylori gastritis. It may be a localised or generalised disease. Examples of locations where histiocytosis may occur include the lungs, pleura, stomach, kidney, bone marrow, thyroid, thymus, and parotid gland. The disease is described as generalised if two or more unrelated sites are involved.
Dermal macrophages are macrophages in the skin that facilitate skin homeostasis by mediating wound repair, hair growth, and salt balance. Their functional role in these processes is the mediator of inflammation. They can acquire an M1 or M2 phenotype to promote or suppress an inflammatory response, thereby influencing other cells' activity via the production of pro-inflammatory or anti-inflammatory cytokines. Dermal macrophages' ability to acquire pro-inflammatory properties also potentiates them in cancer defence. M1 macrophages can suppress tumour growth in the skin by their pro-inflammatory properties. However, M2 macrophages support tumour growth and invasion by the production of Th2 cytokines such as TGFβ and IL-10. Thus, the exact contribution of each phenotype to cancer defence and the skin's homeostasis is still unclear.
References
- ↑ Cline, Mj (1 November 1994). "Histiocytes and histiocytosis". Blood. 84 (9): 2840–2853. doi: 10.1182/blood.V84.9.2840.2840 .
- ↑ Chorro L, Geissmann F (December 2010). "Development and homeostasis of 'resident' myeloid cells: the case of the Langerhans cell". Trends in Immunology. 31 (12): 438–45. doi:10.1016/j.it.2010.09.003. PMID 21030305.
- ↑ "S12C3-Granuloma". Archived from the original on 2009-09-29. Retrieved 2009-01-06.
- ↑ Cline MJ (November 1994). "Histiocytes and histiocytosis". Blood. 84 (9): 2840–53. doi: 10.1182/blood.V84.9.2840.2840 . PMID 7524755.
- ↑ Webb DK (October 1996). "Histiocyte disorders". British Medical Bulletin. 52 (4): 818–25. doi: 10.1093/oxfordjournals.bmb.a011585 . PMID 9039734.