FACTOID # 19: Cheap sloppy joes: Looking for reduced-price lunches for schoolchildren? Head for Oklahoma!
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Dendritic cell

Dendritic cells (DC) are immune cells and form part of the mammal immune system. They are present at a low frequency in those tissues which are in contact with the environment: in the skin (where they are often called Langerhans cells) and the lining of nose, lungs, stomach and intestines. Especially in immature state, they can also be found in blood. Once activated, they migrate to the lymphoid tissues where they interact with T cells and B cells to initiate and shape the immune response. In certain stages they have long spiky arms, called dendrites, from which their name is derived. While neurons also have dendrites, they are not related to DCs. In both types of cell, the dendrites seem to serve the same purpose: to enable a single cell to contact a large number of other cells at one time (the dendrites confer a high surface-to-volume ratio.) The name veiled cells refers to immature or maturing dendritic cells; these cells do not yet possess the dendrites, but rather larger cytoplasmic 'veils'. White Blood Cells is also the name of a White Stripes album. ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... The immune system is the system of specialised cells and organs that protect an organism from outside biological influences. ... Diagram of the layers of human skin In zootomy and dermatology, skin is an organ of the integumentary system composed of a layer of tissues that protect underlying muscles and organs. ... Langerhans cells are immature dendritic cells containing large granules called Birbeck granules. ... Human nose in profile The Nose is a story by Gogol and an opera by Dmitri Shostakovich. ... The lungs flank the heart and great vessels in the chest cavity. ... The stomach (Gaster) In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the gastrointestinal tract used to digest food. ... The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and mammals, consists of two segments, the small intestine and the large intestine. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ...

Contents


Types of dendritic cells

Unfortunately, there are at least two different types of cells involved with immunity that are called dendritic cells. The exact relationship of these types to each other, as well as the identity of their parent cells in vivo, remains controversial.


While humans and non-human primates such as Rhesus macaques appear to have DCs divided into these groups, other species (such as the mouse) have different subdivisions of DCs. [[{{{diversity_link}}}|Diversity]] {{{diversity}}} Binomial name Macaca mulatta Zimmermann, 1780 Trinomial name {{{trinomial}}} Type Species {{{type_species}}} {{{subdivision_ranks}}} [[Image:{{{range_map}}}|{{{range_map_width}}}|]] Synonyms {{{synonyms}}} The Rhesus Macaque (Macaca mulatta), often called the Rhesus Monkey, is one of the best known species of Old World monkeys. ... Feral mouse A mouse is a mammal that belongs to one of numerous species of small rodents in the genus Mus and various related genera of the family Muridæ (Old World Mice). ...


In vivo

  • Myeloid dendritic cells (MDC) are most similar to monocytes. MDC are made up of at least two subsets:
    • the more common MDC-1
    • the extremely rare MDC-2, which may have a function in fighting wound infection
  • Plasmacytoid dendritic cells (PDC) look like plasma cells, but have certain characteristics similar to myeloid dendritic cells. They can produce high amounts of interferon-alpha and have thus become known as IPC (interferon-producing cells) before their dendritic cell nature was revealed.
  • Follicular dendritic cells (FDC) that are probably not of hematopoietic origin, but simply look similar to 'true' dendritic cells.

MONOCYTES: Plural of monocyte. ... Plasma cells are B lymphocytes that secrete immunoglobulins (antibodies). ... Interferons (IFNs) are natural proteins produced by the cells of the immune systems of most animals in response to challenges by foreign agents such as viruses, bacteria, parasites and tumor cells. ... Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ...

In vitro

In some respects, dendritic cells cultured in vitro do not show the same behavior or capability as dendritic cells isolated ex vitro, but they are often used for research, as they are still much more readily available than genuine DCs. Wiktionary has a definition of: In vitro In vitro (Latin: within glass) means within a test tube, or, more generally, outside a living organism or cell. ...

MONOCYTES: Plural of monocyte. ... Sketch of bone marrow and its cells Pluripotential hemopoietic stem cells or pluripotential hematopoietic stem cells (PHSCs) are stem cells found in the bone marrow. ...

Life cycle

Dendritic cells start out as immature dendritic cells. These cells are characterized by high endocytic activity and low T-cell activation potential. Dendritic cells constantly sample the surroundings for pathogens such as viruses and bacteria. This is done through pattern recognition receptors (PRRs) such as the toll-like receptors (TLRs). TLRs recognize specific chemical signatures found on subsets of pathogens. Once they have come into contact with such a pathogen, they become activated into mature dendritic cells. Immature dendritic cells phagocytose pathogens and degrade its proteins into small pieces and upon maturation present those fragments at their cell surface using MHC molecules. Simultaneously, they upregulate cell-surface receptors that act as co-receptors in T-cell activation such as CD80 and CD86, greatly enhancing their ability to activate T-cells. They also upregulate CCR7, a chemotactic receptor that induces the dendritic cell to travel through the blood stream to the spleen or through the lymphatic system to a lymph node. Here they act as antigen-presenting cells: they activate helper T-cells and killer T-cells as well as B-cells by presenting them with antigens derived from the pathogen, alongside non-antigen specific costimulatory signals. A common alternate meaning of virus is computer virus. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... It has been suggested that Class I MHC be merged into this article or section. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... The spleen is a ductless, vertebrate gland that is not necessary for life but is closely associated with the circulatory system, where it functions in the destruction of old red blood cells and removal of other debris from the bloodstream, and also in holding a reservoir of blood. ... Lymph originates as blood plasma lost from the circulatory system, which leaks out into the surrounding tissues. ... Structure of the lymph node. ... An antigen presenting cell (APC) is a cell that displays foreign antigen complexed with MHC on its surface. ... A helper (or TH) T cell is a T cell (a type of white blood cell) which has on its surface antigen receptors that can bind to fragments of antigens displayed by the Class II MHC molecules found on professional antigen-presenting cells (APCs). ... A K cell (or a killer cell) is a lymphocyte with immunoglobulin Fc receptors, which allow it to bind to and kill antibody-coated cells by antibody-dependent cell-mediated cytotoxicity (ADCC). ... B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response). ...


Every helper T-cell is specific to one particular antigen. Only professional antigen-presenting cells (macrophages, B lymphocytes, and dendritic cells) are able to activate a helper T-cell which has never encountered its antigen before. Dendritic cells are the most potent of all the antigen-presenting cells.


As mentioned above, MDC probably form from monocytes, white blood cells which circulate in the body and, depending on the right signal, can turn into either dendritic cells or macrophages. Activated macrophages have a lifespan of only a few days. The lifespan of activated dendritic cells, while somewhat varying according to type and origin, is of a similar order of magnitude, but immature dendritic cells seem to be able to exist in an unactivated state for much longer. The monocytes in turn are formed from stem cells in the bone marrow. However, the exact genesis and development of the different types and subsets of dendritic cells and their interrelationship is only marginally understood at the moment, as dendritic cells are so rare and difficult to isolate that only in recent years they have become subject of focused research. Distinct surface antigens that characterize dendritic cells have only become known from 2000 on; before that, researchers had to work with a 'cocktail' of several antigens which, in combination, are unique to DCs. A monocyte is a leukocyte, part of the human bodys immune system that protect against blood-borne pathogens and move quickly to sites of infection in the tissues. ... Macrophages (Greek: big eaters) are cells found in tissues that are responsible for phagocytosis of pathogens, dead cells and cellular debris. ... We are very sorry this search engine is being modified and customized at the moment. ...


Relationship to HIV, allergy, and autoimmune diseases

HIV, which causes AIDS, can bind to dendritic cells via various receptors expressed on the cell. The best studied example is DC-SIGN (usually on MDC subset 1, but other subsets under certain conditions; since not all dendritic cell subsets expresss DC-SIGN, its exact role in sexual HIV-1 transmission is not clear). When the dendritic cell takes up HIV and then travels to the lymph node, the virus is able to move to helper T-cells, and this infection of helper T-cells is the major cause of disease. This knowledge has vastly altered our understanding of the infectious cycle of HIV since the mid-1990s, since in the infected dendritic cells, the virus possesses a reservoir which also would have to be targeted by a therapy. This infection of dendritic cells by HIV explains one mechanisms by which the virus could persist after prolonged HAART. Many other viruses, such as the SARS virus seems to use DC-SIGN to 'hitchhike' to its target cells. However, most work with virus binding to DC-SIGN expressing cells has been conducted using in vitro derived cells such as moDCs. The physiological role of DC-SIGN in vivo is more difficult to ascertain. Human immunodeficiency virus, commonly known by the acronym HIV, is a retrovirus that primarily infects vital components of the human immune system such as CD4+ T cells, macrophages and dendritic cells. ... The Red Ribbon is the global symbol for solidarity with HIV-positive people and those living with AIDS. AIDS, or Aids, is an acronym for acquired immunodeficiency syndrome or acquired immune deficiency syndrome and is defined as a collection of symptoms and infections resulting from the specific damage to the... The term antiretroviral drugs is used to describe drugs used against HIV infection (HIV is an RNA retrovirus). ... Severe Acute Respiratory Syndrome (SARS) is an atypical form of pneumonia. ...


Altered function of dendritic cells is also known to play a major or even key role in allergy and autoimmune diseases like lupus erythematosus. Allergy is a pathologically overblown reaction to an outside allergen, autoimmune diseases are erroneous immune reactions to self-antigen. An allergy or Type I hypersensitivity is an immune malfunction whereby a persons body is hypersensitised to react immunologically to typically nonimmunogenic substances. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ...


Dendritic cells in animals other than humans

The above applies to humans. In other organisms, the function of dendritic cells can differ slightly. For example, in brown rats (but not mice), a subset of dendritic cells exists that displays strong killer cell-like activity. However, the principal function of dendritic cells as known to date is always to act as the generals or an "central encyclopedia" of the immune response, collecting and storing immunological knowledge, enabling them to instruct the adaptive arms to respond invading pathogens and telling the adaptive immune system what the most effective type of response is. Binomial name Rattus norvegicus (Berkenhout, 1769) The Brown Rat or Norway Rat (Rattus norvegicus) is one of the most well-known and common rats, and also one of the largest. ...


External links

  • Illustration
  • Presentation
  • Activation
  • Illustration

References

  • Jacques Banchereau: The Long Arm of the Immune System, Scientific American Vol. 287, No. 5 (November 2002), pp. 52 - 59 (summary of dendritic cell knowledge)
  • A. Dzionek et al.: BDCA-2, BDCA-3, and BDCA-4: three markers for distinct subsets of dendritic cells in human peripheral blood, J. Immunol. Vol. 165, No. 11 (December 2000), pp. 6037 - 6046 (detailed description of MDC-1, MDC-2, PDC phenotypes)
  • Kelli McKenna et al.: Plasmacytoid Dendritic Cells: Linking Innate and Adaptive Immunity, J. Virol. Vol. 79 No. 1 (January 2005), pp. 17–27 (summary of current knowledge about dendritic cells and PDC in particular)
  • Zhi-Yong Yang et al.: pH-Dependent Entry of Severe Acute Respiratory Syndrome Coronavirus Is Mediated by the Spike Glycoprotein and Enhanced by Dendritic Cell Transfer through DC-SIGN, J. Virol. Vol. 78, No. 11 (June 2004), pp. 5642 – 5650 (dendritic cells in SARS)


Blood - Blood plasma
Pluripotential hemopoietic stem cell - Red blood cells (Reticulocyte, Normoblast) - White blood cells
Lymphocytes (Lymphoblast)
T cells (Cytotoxic - Helper - Regulatory T cell) - B cells (Plasma cells & Memory B cells) - Natural killer cell
Myelocytes (Myeloblast)
Granulocytes (Neutrophil, Eosinophil, Basophil) - Mast cell precursors - Monocytes (Histiocyte, Macrophages, Dendritic cells, Langerhans cells, Microglia, Kupffer cells) - Megakaryoblast - Megakaryocyte - Platelets

  Results from FactBites:
 
Dendritic cell - definition of Dendritic cell in Encyclopedia (455 words)
Dendritic cells are immune cells and form part of the mammal immune system.
Dendritic cells form from monocytes, white blood cells which circulate in the body and, depending on the right signal, can turn into dendritic cells or macrophages.
HIV, which causes AIDS, is attracted by one particular kind of dendritic cell; when these get infected and then travel to lymph nodes, the virus is able to move to helper T-cells, and this infection of helper T-cells is the major cause of disease.
Dendritic cell - Wikipedia, the free encyclopedia (1188 words)
The lifespan of activated dendritic cells, while somewhat varying according to type and origin, is of a similar order of magnitude, but immature dendritic cells seem to be able to exist in an unactivated state for much longer.
However, the exact genesis and development of the different types and subsets of dendritic cells and their interrelationship is only marginally understood at the moment, as dendritic cells are so rare and difficult to isolate that only in recent years they have become subject of focused research.
When the dendritic cell takes up HIV and then travels to the lymph node, the virus is able to move to helper T-cells, and this infection of helper T-cells is the major cause of disease.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m