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Encyclopedia > Macrophage
A macrophage of a mouse stretching its arms to engulf two particles, possibly pathogens
A macrophage of a mouse stretching its arms to engulf two particles, possibly pathogens

Macrophages (Greek: "big eaters", from makros "large" + phagein "eat") are cells within the tissues that originate from specific white blood cells called monocytes. Monocytes and macrophages are phagocytes, acting in both nonspecific defense (or innate immunity) as well as specific defense (or cell-mediated immunity) of vertebrate animals. Their role is to phagocytose (engulf and then digest) cellular debris and pathogens either as stationary or mobile cells, and to stimulate lymphocytes and other immune cells to respond to the pathogen. Image File history File linksMetadata Download high resolution version (1280x1024, 279 KB) Summary A macrophage of a mouse stretching itself to eat two smaller particles, possibly pathogens. ... Image File history File linksMetadata Download high resolution version (1280x1024, 279 KB) Summary A macrophage of a mouse stretching itself to eat two smaller particles, possibly pathogens. ... This article is about the animal. ... “White Blood Cells” redirects here. ... Monocyte 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. ... A phagocyte is a cell that ingests and destroys foreign matter such as microorganisms or debris via a process known as phagocytosis. ... Innate immunity is immunity that the body possesses naturally, as opposed to adaptive immunity. ... Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. ... Steps of a macrophage ingesting a pathogen: a. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ... A scanning electron microscope (SEM) image of a single human lymphocyte. ...

Contents

Life cycle

When a monocyte enters damaged tissue through the endothelium of a blood vessel (a process known as the leukocyte adhesion cascade), it undergoes a series of changes to become a macrophage. Monocytes are attracted to a damaged site by chemical substances through chemotaxis, triggered by a range of stimuli including damaged cells, pathogens, histamine released by mast cells and basophils, and cytokines released by macrophages already at the site. At some sites such as the testis, macrophages have been shown to populate the organ through proliferation. Monocyte 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. ... The endothelium is the layer of thin, flat cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. ... f you all The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... The Leukocyte adhesion cascade is a process through which leukocytes (white blood cells) leave blood vessels and enter injured tissue. ... Chemotaxis is a kind of taxis, in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. ... This article or section does not cite any references or sources. ... Mast cells A mast cell (or mastocyte) is a resident cell of areolar connective tissue (loose connective tissue) that contains many granules rich in histamine and heparin. ... Categories: Wikipedia cleanup | Biology stubs | Blood and immune system cells ... Cytokines are small protein molecules that are the core of communication between immune system cells, and even between immune system cells and cells belonging to other tissue types. ...


Unlike short-lived neutrophils the life span of a macrophage ranges from months to years.


Function

Steps of a macrophage ingesting a pathogen:a. Ingestion through phagocytosis, a phagosome is formedb. The fusion of lysosomes with the phagosome creates a phagolysosome; the pathogen is broken down by enzymesc. Waste material is expelled or assimilated (the latter not pictured)Parts:1. Pathogens2. Phagosome3. Lysosomes4. Waste material5. Cytoplasm6. Cell membrane
Steps of a macrophage ingesting a pathogen:

a. Ingestion through phagocytosis, a phagosome is formed
b. The fusion of lysosomes with the phagosome creates a phagolysosome; the pathogen is broken down by enzymes
c. Waste material is expelled or assimilated (the latter not pictured)

Parts:

1. Pathogens
2. Phagosome
3. Lysosomes
4. Waste material
5. Cytoplasm
6. Cell membrane

Image File history File links Download high resolution version (2352x1611, 185 KB) Summary A happy macrophage ingesting not so happy pathogens Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version... Image File history File links Download high resolution version (2352x1611, 185 KB) Summary A happy macrophage ingesting not so happy pathogens Licensing I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version... A phagolysosome is a membrane-bound organelle which is formed from the fusing of a lysosome and a phagosome. ... This article or section is in need of attention from an expert on the subject. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ... In cell biology, a vacuole formed around a particle absorbed by phagocytosis. ... Various organelles labeled. ... Organelles. ... Look up cell membrane in Wiktionary, the free dictionary. ...

Phagocytosis

Main article: Phagocytosis

One important main role of macrophage is the removal of necrotic debris and dust in the lungs. Removing dead cell material is important in chronic inflammation as the early stages of inflammation are dominated by neutrophil granulocytes, which are ingested by macrophages if they come of age (see CD-31 for a description of this process.) Steps of a macrophage ingesting a pathogen: a. ... Necrosis (in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. ... Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ... This article does not cite any references or sources. ... CD31 is a cluster of differentiation molecule. ...


The removal of dust and necrotic tissue is to a greater extent handled by fixed macrophages, which will stay at strategic locations such as the lungs, liver, neural tissue, bone, spleen and connective tissue, ingesting foreign materials such as dust and pathogens, calling upon wandering macrophages if needed.


When a macrophage ingests a pathogen, the pathogen becomes trapped in a food vacuole, which then fuses with a lysosome. Within the lysosome, enzymes and toxic peroxides digest the invader. However, some bacteria, such as Mycobacterium tuberculosis, have become resistant to these methods of digestion. Macrophages can digest more than 100 bacteria before they finally die due to their own digestive compounds. Schematic of typical animal cell, showing subcellular components. ... Various organelles labeled. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Binomial name Zopf 1883 Mycobacterium tuberculosis is the bacterium that causes most cases of tuberculosis. ...


Role in specific immunity

Macrophages are versatile cells that play many roles. As scavengers, they rid the body of worn-out cells and other debris. They are foremost among the cells that "present" antigen; a crucial role in initiating an immune response. As secretory cells, monocytes and macrophages are vital to the regulation of immune responses and the development of inflammation; they churn out an amazing array of powerful chemical substances (monokines) including enzymes, complement proteins, and regulatory factors such as interleukin-1. At the same time, they carry receptors for lymphokines that allow them to be "activated" into single-minded pursuit of microbes and tumor cells. A monokine is a type of cytokine produced primarily by monocytes and macrophages. ... Interleukin-1 (IL-1) is one of the first cytokines ever described. ... Lymphokines are a subset of Cytokines that are produced by immune cells. ...


After digesting a pathogen, a macrophage will present the antigen (a molecule, most often a protein found on the surface of the pathogen, used by the immune system for identification) of the pathogen to a corresponding helper T cell. The presentation is done by integrating it into the cell membrane and displaying it attached to a MHC class II molecule, indicating to other white blood cells that the macrophage is not a pathogen, despite having antigens on its surface. For the server security software, see Microsoft Forefront. ... 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). ... Protein images comparing the MHC I (1hsa) and MHC II (1dlh) molecules. ...


Eventually the antigen presentation results in the production of antibodies that attach to the antigens of pathogens, making them easier for macrophages to adhere to with their cell membrane and phagocytose. In some cases, pathogens are very resistant to adhesion by the macrophages. Coating an antigen with antibodies could be compared to coating something with Velcro to make it stick to fuzzy surfaces. Each antibody binds to a specific antigen; an interaction similar to a lock and key. ... Velcro: hooks (left) and loops (right). ...


The antigen presentation on the surface of infected macrophages (in the context of MHC class II) in a lymph node stimulates TH1 (type 1 helper T cells) to proliferate (mainly due to IL-12 secretion from the macrophage). When a B-cell in the lymph node recognizes the same unprocessed surface antigen on the bacterium with its surface bound antibody, the antigen is endocytosed and processed. The processed antigen is then presented in MHCII on the surface of the B-cell. TH1 receptor that has proliferated recognizes the antigen-MHCII complex (with co-stimulatory factors- CD40 and CD40L) and causes the B-cell to produce antibodies that help opsonization of the antigen so that the bacteria can be better cleared by phagocytes. MHC may refer to: Major histocompatibility complex, a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions Managed health care Mars Hill College, a coeducational liberal-arts college affiliated with the North Carolina Baptist Convention in Mars Hill, North Carolina, USA Matthew Henry Commentary (Biblical) Mental... T helper cells (also known as effector T cells or Th cells) are a sub-group of lymphocytes (a type of white blood cell or leukocyte) that play an important role in establishing and maximising the capabilities of the immune system. ... Interleukin 12 (IL-12) is an interleukin that are naturally produced by macrophages and human B-lymphoblastoid cells (NC-37)in response to antigenic stimulation. ... CD40 is a costimulatory protein found on antigen presenting cells. ... An opsonin is any molecule that acts as a binding enhancer for the process of phagocytosis. ... A phagocyte is a cell that ingests (and destroys) foreign matter, such as microorganisms or debris via a process known as phagocytosis, in which these cells ingest and kill offending cells by cellular digestion. ...


Macrophages provide yet another line of defense against tumor cells and body cells infected with fungus or parasites. Once a T cell has recognized its particular antigen on the surface of an aberrant cell, the T cell becomes an activated effector cell, releasing chemical mediators known as lymphokines that stimulate macrophages into a more aggressive form. These activated or angry macrophages, can then engulf and digest affected cells much more readily.[1] The angry macrophage does not generate a response specific for an antigen, but attacks the cells present in the local area in which it was activated.[1] Subkingdom/Phyla Chytridiomycota Blastocladiomycota Neocallimastigomycota Glomeromycota Zygomycota Dikarya (inc. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Lymphokines are a subset of Cytokines that are produced by immune cells. ...


Fixed macrophages

A majority of macrophages are stationed at strategic points where microbial invasion or accumulation of dust is likely to occur, each type of macrophage, determined by its location, has a specific name:

Macrophage
Macrophage
Name of cell Location
Dust cells/Alveolar macrophages pulmonary alveolus of lungs
Histiocytes connective tissue
Kupffer cells liver
Microglial cells neural tissue
Osteoclasts bone
Sinusoidal lining cells spleen

Investigations concerning Kupffer cells are hampered because in humans Kupffer cells are only accessible for immunohistochemical analysis from biopsies or autopsies. From rats and mice they are difficult to isolate and after purification only approximately 5 million cells can be obtained from one mouse. Image File history File links Macrophage. ... Image File history File links Macrophage. ... A dust cell (or alveolar macrophage) is a type of macrophage found in the pulmonary alveolus, near the pneumocytes, but separated from the wall. ... Detailed drawing of the alveoli from Grays Anatomy, 1918 - Schematic longitudinal section of a primary lobule of the lung (anatomical unit); r. ... The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... A Histiocyte is a cell that is part of the human immune system. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... Kupffer cells or Browicz-Kupffer cells are specialized macrophages located in the liver that form part of the reticuloendothelial system. ... For the bird, see Liver bird. ... Microglia cells positive for lectins Microglia are a type of glial cell that act as the immune cells of the Central nervous system (CNS). ... The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and processes input from the senses, and initiates actions. ... This article is about the skeletal organs. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ... The spleen is an organ located in the abdomen, where it functions in the destruction of old red blood cells and holding a reservoir of blood. ...


Macrophages can express paracrine functions within organs that are specific to the function of that organ. In the testis for example, macrophages have been shown to be able to interact with Leydig cells by secreting 25-hydroxycholesterol, an oxysterol that can be converted to testosterone by neighboring Leydig cells. Also, testicular macrophages may participate in creating an immune privileged environment in the testis, and in mediating infertility during inflammation of the testis.


Involvement in symptoms of diseases

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. H&E section of non-caseasting granuloma seen in the colon of a patient with Crohns disease In medicine (anatomical pathology), a granuloma is a group of epithelioid macrophages surrounded by a lymphocyte cuff. ...


Some disorders, mostly rare, of ineffective phagocytosis and macrophage function have been described.


Macrophages are the predominant cells involved in creating the progressive plaque lesions of atherosclerosis.


When fighting influenza, macrophages are dispatched to the throat. However, until the killer T cells for the flu virus are found, the macrophages do more damage than help. They not only destroy throat cells infected with the flu virus but also destroy several surrounding non-infected cells. Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by an RNA virus of the family Orthomyxoviridae (the influenza viruses). ...


Macrophages also play a role in Human Immunodeficiency Virus (HIV) infection. Like T cells, macrophages can be infected with HIV, and even become a reservoir of ongoing virus replication throughout the body. The human immunodeficiency virus (HIV) is a frequently mutating retrovirus that attacks the human immune system and which has been shown to cause acquired immune deficiency syndrome (AIDS). ... T cells are a subset of lymphocytes that play a large role in the immune response. ...


Macrophages are believed to help cancer cell proliferate as well. They are attracted to oxygen-starved (hypoxia) tumour cells and promote chronic inflammation. Inflammatory compounds such as Tumor necrosis factor (TNF) released by the macrophage activates the gene switch nuclear factor-kappa B. NF-kB then enters the nucleus of a tumour cell and turns on production of proteins that stop apoptosis and promote cell proliferation and inflammation. [2] Hypoxia may refer to: Hypoxia (medical), the lack of oxygen in tissues Hypoxia or Oxygen depletion, a reduced concentration of dissolved oxygen in a water body leading to stress or even death in aquatic organisms This is a disambiguation page: a list of articles associated with the same title. ... It has been suggested that this article or section be merged into inflammation. ... In medicine, tumor necrosis factor alpha (TNFα, cachexin or cachectin) is an important cytokine involved in systemic inflammation and the acute phase response. ... NF-κB, or Nuclear Factor kappa B, is a nuclear transcription factor found in all cell types and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, ultraviolet irradiation, and bacterial or viral antigens. ... A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ...


Media

  • Macrophages (J774) interacting with conidia

    An active J774 macrophage is seen taking up at least three
    conidia in a cooperative manner. The J774 cells were
    treated with 5 ng/ml interferon-γ one night before filming with conidia.
    The observation was made over a period of 2.5 h every 30 s.


    Image File history File links S4-J774_Cells_with_Conidia_in_Liquid_Media. ... Image File history File links S4-J774_Cells_with_Conidia_in_Liquid_Media. ... Conidia are asexual spores of fungus. ... Interferon-gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. ...

    Alveolar Macrophages interacting with conidia

    Two highly active alveolar macrophages can be seen ingesting conidia.
    Time lapse is 30 s per frame over 2.5 h.


    Image File history File links S3-Alveolar_Macrophages_with_Conidia_in_Liquid_Medium. ... Image File history File links S3-Alveolar_Macrophages_with_Conidia_in_Liquid_Medium. ... A dust cell (or alveolar macrophage) is a type of macrophage found in the pulmonary alveolus, near the pneumocytes, but separated from the wall. ...

  • Problems seeing the videos? See media help.

Related cells

Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... Langerhans cells are immature dendritic cells containing large granules called Birbeck granules. ... Some common lipids. ... Foam cells are cells in an atheroma derived form both macrophages and smooth muscle cells which have accumulated LDLs by endocytosis. ...

References

  1. ^ a b (March 1988) "The human immune system: The lymphocyte story". New Scientist (1605): 1. Retrieved on 2007-09-13. 
  2. ^ Gary Stix: "A Malignant Flame", Scientific American, July 2007, pages 46-49

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 256th day of the year (257th in leap years) in the Gregorian calendar. ...

See also

Tetrachlorodecaoxide (TCDO) is a chlorite containing drug used for the dressing of wounds,immunomodulation and as radiation protective agent. ... Tetrachlorodecaoxide (TCDO) is a chlorite containing drug used for the dressing of wounds,immunomodulation and as radiation protective agent. ... An immunomodulator is a drug used for its effect on the immune system: drugs may be immunosuppressants or immunostimulators. ...

External links


  Results from FactBites:
 
macrophage - definition of macrophage in Encyclopedia (431 words)
Microglia are macrophages in the brain, and Kupffer cells are macrophages in the liver.
Macrophages are the predominate cells involved in creating the progressive plaque lesions of atherosclerosis.
It is initiated by lymphokines, such as the macrophage activation factor (maf) and the macrophage migration-inhibitory factor (mmif), immune complexes, c3b, and various peptides, polysaccharides, and immunologic adjuvants.
  More results at FactBites »

 
 

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