Macrophage Health Dictionary

Macrophage: From 4 Different Sources


A cell in the immune system.

Macrophages are large phagocytes, which can engulf and destroy microorganisms and other foreign particles.

They are found in most body tissues.

Health Source: BMA Medical Dictionary
Author: The British Medical Association
This is a mature form of what is released from the marrow as a monocyte. A macrophage lives long, can digest much detritus, and is able to wear particles of odd food on its outer membrane. This allows T-cell and B-cell Iymphocytes to taste the particle (an epitope) and form an antibody response. Further, these macrophages, traveling as monocytes, will take up permanent residence in many tissues, providing them with immunity. They line the spleen, form the cleansing Kupffer cells in the liver, make up the “dust cells” that protect the lungs, protect the synovial fluids of the joints, and form the microglial cells that provide protection to the brain and nerve tissues. On and on, the macrophages clean up messes and acting as the intermediates between innate and acquired immunity.
Health Source: Herbal Medical
Author: Health Dictionary
A large PHAGOCYTE that forms part of the RETICULO-ENDOTHELIAL SYSTEM. It is found in many organs and tissues, including connective tissue, bone marrow, lymph nodes, spleen, liver and central nervous system. Free macrophages move between cells and, using their scavenger properties, collect at infection sites to remove foreign bodies, including bacteria. Fixed macrophages are found in connective tissue.
Health Source: Medical Dictionary
Author: Health Dictionary
n. a large scavenger cell (a *phagocyte) present in connective tissue and many major organs and tissues, including the bone marrow, spleen, *lymph nodes, liver (see Kupffer cells), and the central nervous system (see microglia). They are closely related to *monocytes. Fixed macrophages (histiocytes) are stationary within connective tissue; free macrophages wander between cells and aggregate at focal sites of infection, where they remove bacteria or other foreign bodies from blood or tissues. See also reticuloendothelial system.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Connective Tissue

Sometimes called ?brous tissue, this is one of the most abundant tissues in the body, holding together the body’s many di?erent structures. Connective tissue comprises a matrix of substances called mucopolysaccharides in which are embedded various specialist tissues and cells. These include elastic (yellow), collagenous (white) and reticular ?bres as well as macrophages (see MACROPHAGE) and MAST CELLS. Assembled in di?ering proportions, this provides structures with varying functions: bone, cartilage, tendons, ligaments and fatty and elastic tissues. Collagenous connective tissue binds the muscles together and provides the substance of skin. It is also laid down in wound repair, forming the scar tissue. Contracting with time, connective tissue becomes denser, causing the puckering that is typical in serious wounds or burns. (See ADHESION; SCAR; WOUNDS.)... connective tissue

Phagocyte

Cells – including monocytes (a variety of LEUCOCYTES) in the blood and macrophages (see MACROPHAGE) in the tissues – that envelop and digest BACTERIA cells, cell debris and other small particles. Phagocytes are an essential part of the body’s defence mechanisms.... phagocyte

Whipple’s Disease

A rare disorder, also called intestinal lipodystrophy, that can affect many organs. Symptoms include steatorrhoea as a result of malabsorption, abdominal pain, joint pains, progressive weight loss, swollen lymph nodes, anaemia, and fever. The heart, lungs, and brain can also be affected. The condition is most common in middle-aged men.

The cause is thought to be bacterial; affected tissues are found to contain macrophages (a type of scavenging cell) containing rod-shaped bacteria. Treatment is with antibiotic drugs for at least 1 year. Dietary supplements are used to correct nutritional deficiencies occurring as a result of malabsorption.... whipple’s disease

Aloe Barbadensis

Mill.

Synonym: A. Vera Tourn. Ex Linn. A. indica Royle A. littoralis Koening

Family: Liliaceae; Agavaceae.

Habitat: Cultivated throughout India, wild on coasts of Maharashtra, Gujarat and South India.

English: Curacao Aloe, Barbados Aloe, Indian Aloe, Jaffarabad Aloe.

Ayurvedic: Kanyaasaara, Eleyaka (dried juice of the leaves). Kumaari, Kumaarikaa, Kanyaa, Grihkanyaa, Ghritkumaarika (plant).

Unani: Gheekwaar, Sibr.

Siddha/Tamil: Sotru Kattraazhai, Kumaari. Moosaambaram (dried juice).

Folk: Elwaa, Musabbar (dried juice of leaves).

Action: Purgative (causes griping), emmenagogue. Gel—topically emollient, anti-inflammatory, antimicrobial (used for wound healing, sunburn).

Key application: In occasional constipation; contraindicated in intestinal obstruction and acutely inflamed intestinal diseases, ulcerative colitis, appendicitis. (German Commission E, ESCOP, WHO.)

The Ayurvedic Pharmacopoeia of India recommends the use of dried juice of leaves in dysmenorrhoea and diseases of the liver.

Aloe vera improved the hypoglycaemic effect of glyburide (gliben- clamide) when one tablespoonful aloe juice was given orally in the morning and at bedtime to 36 diabetic patients for 42 days. The juice (same dose) showed antihyperglycaemic activity (independently). (Francis Brinker.)

Anthraquinone glycosides, known as aloin, in small doses act as a tonic to the digestive system, and at higher doses become a strong purgative, as well as increase colonic secretions and peristaltic contractions. Resin fraction is also as important as aloin in cathartic action. In A. barbadensis the highest percentage of aloin is 21.8%.

Aloe produces pelvic congestion and is used for uterine disorders, generally with Fe and carminatives. The pulp is used in menstrual suppressions.

A molecule in the Aloe vera gel, ace- mannan, stimulates macrophages and releases immune system potentiators; enhances function of T cells and interferon production. Animal studies have shown promising results in sarcoma.

The carboxypeptidase and salicylate components of Aloe gel can inhibit bradykinin, a pain-producing agent; C-glycosyl chromone appears to reduce topical inflammation. Aloe gel also slows or inhibits the synthesis of thromboxane, which may accelerate the healing of burns. (Natural Medicines Comprehensive Database, 2007.)

Dosage: Leaf pulp juice—10-20 ml. (CCRAS.) Dried leaf pulp juice— 125-500 mg powder. (API Vol. I.)... aloe barbadensis

Andrographis Panicultata

Wall. ex Nees

Family: Acanthaceae.

Habitat: Throughout India, from Himachal Pradesh to Assam and Mizoram, and all over southern India.

English: Creat.

Ayurvedic: Kaalmegha, Bhuunimba, Bhuuminimbaka, Vishwambharaa, Yavtikta, Kalpanaatha, Kiraata-tikta (var.).

Unani: Kiryaat.

Siddha/Tamil: Nilavembu.

Action: Hepatoprotective, cholin- ergic, antispasmodic, stomachic, anthelmintic, alterative, blood purifier, febrifuge. It acts well on the liver, promoting secretion of bile. Used in jaundice and torpid liver, flatulence and diarrhoea of children, colic, strangulation of intestines and splenomegaly; also for cold and upper respiratory tract infections.

Key application: As bitter tonic, febrifuge and hepatoprotective. (Indian Herbal Pharmacopoeia.)

Kaalmegha, officinal in IP, consists of dried leaves and tender shoots, which yield not less than 1% andro- grapholide on dry-weight basis.

Several active constituents have been identified from the leaf and rhizome, including andrographolide, deoxyan- drographolide and other diterpenes.

Andrographolide exhibited strong choleretic action when administered i.p. to rats. It induces increase in bile flow together with change in physical properties of bile secretion. It was found to be more potent than sily- marin.

Andrographolide was found to be almost devoid of antihepatitis-B virus surface antigen-like activity (when compared with picroliv.)

The leaf and stem extracts of Kaal- megha/andrographolide given s.c. or orally did not change blood sugar level of normal or diabetic rats.

Alcoholic extract of the plant exhibited antidiarrhoeal activity against E. coli enterotoxins in animal models.

Clinical evidence of effectiveness of andrographis in humans is limited to the common cold. Preliminary evidence suggests that it might increase antibody activity and phagocytosis by macrophages, and might have mast cell-stabilizing and antiallergy activity. (Natural Medicines Comprehensive Database, 2007.)

The herb is contraindicated inbleed- ing disorders, hypotension, as well as male and female sterility (exhibited infertility in laboratory animals).

Dosage: Whole plant—5-10 ml juice; 50-100 ml decotion; 1-3 g powder. (CCRAS.)... andrographis panicultata

Complement

A large body of blood proteins (over 20), initiated in the liver, and intimately involved in nearly all aspects of immunity and nonspecific resistance. They form two types of self-mediated cascade reactions to antigens, antibody-antigen complexes, dead tissue and the like, and are almost solely able to initiate the rupture and killing of bacteria. The protein strings they form around foreign substances are the main “hooks” used for absorption by macrophages as they digest and clean up.... complement

Cytokine

Also lymphokine, a broad term for a variety of proteins and neuropeptides that lymphocytes and macrophages use to communicate between themselves, often from long distances. They stimulate organization and antibody responses, seem to induce the bone marrow to proliferate the type of white blood cells needed for immediate resistance, and generate sophistication and fine tuning for an overall strategy of resistance. A lymphocyte FAX.... cytokine

Granulocytes

These are a group of white blood cells that have many and well-pigmented granules, and derive from the bone marrow myeloblasts. The granules are sources of digestive, immunologic, and inflammatory proteins. The classic granulocytes are neutrophils, eosinophils, and basophils, but one should also include mast cells. Also, macrophages, which start out as agranulocytic monocytes but get lots of granules when they grow up.... granulocytes

Aristolochia Longa

Linn.

Family: Aristolochiaceae. English: European Birthwort. Unani: Zaraawand Taweel.

Action: Oxytocic, abortifacient, emmenagogue.

Aristolochic acid and its Me es- ter—strongly abortifacient, showed damage to liver and kidney. Roots— anti-oestrogenic. A cytotoxic lignan, savinin, has been isolated from the roots.

Aristolochic acid also has an effect against adenosarcoma and HeLa cells in culture; however, it is suspected to be carcinogenic.

Aristolochia extracts show a pronounced enhancement of phagocytosis by leucocytes, granulocytes and peritoneal macrophages, due to the presence of aristolochic acids.

Tardolyt-coated tablets, which contain 0.3 mg of aristolochic acid, increase phagocytosis in healthy men.

Aristolochic acid also exhibits reduction of some of the toxic effects of prednisolone, chloramphenicol and tetracycline in experiments in vitro, and a reduction in the rate of recurrent herpes lesions in vivo.... aristolochia longa

Erythrocytes

The biconcave red blood cells that carry oxygen from the lungs to the tissues, and return carbon dioxide (see also RESPIRATION). They have an excess of membrane, some of which may be lost in various disorders, as a result of which they become progressively more spherical and rigid. Erythrocytes, which have no nuclei, are formed during ERYTHROPOEISIS from ERYTHROBLASTS in the BONE MARROW, and each mm3 of blood contains 5 million of them. They are by far the largest constituent among the blood cells and they contain large amounts of the oxygen-carrier HAEMOGLOBIN. They have a life of about 120 days after which they are absorbed by macrophages (see MACROPHAGE), the blood’s scavenging cells. Most components of the erythrocytes, including the red pigment haemoglobin, are re-used, though some of the pigment is broken down to the waste product BILIRUBIN.... erythrocytes

Leucocytes

The scienti?c name for white blood cells. Leucocytes contain no HAEMOGLOBIN so are colourless, and have a well-formed NUCLEUS. Healthy people have around 8,000 leucocytes per cubic millimetre of blood. There are three main classes of white cells: granulocytes, lymphocytes and monocytes.

Granulocytes Also known as polymorphonuclear leucocytes (‘polys’), these normally constitute 70 per cent of the white blood cells. They are divided into three groups according to the staining reactions of these granules: neutrophils, which stain with neutral dyes and constitute 65–70 per cent of all the white blood cells; eosinophils, which stain with acid dyes (e.g. eosin) and constitute 3–4 per cent of the total white blood cells; and basophils, which stain with basic dyes (e.g. methylene blue) and constitute about 0·5 per cent of the total white blood cells.

Lymphocytes constitute 25–30 per cent of the white blood cells. They have a clear, non-granular cytoplasm and a relatively large nucleus which is only slightly indented. They are divided into two groups: small lymphocytes, which are slightly larger than erythrocytes (about 8 micrometres in diameter); and large lymphocytes, which are about 12 micrometres in diameter.

Monocytes Motile phagocytic cells that circulate in the blood and migrate into the tissues, where they develop into various forms of MACROPHAGE such as tissue macrophages and KUPFFER CELLS.

Site of origin The granulocytes are formed in the red BONE MARROW. The lymphocytes are formed predominantly in LYMPHOID TISSUE. There is some controversy as to the site of origin of monocytes: some say they arise from lymphocytes, whilst others contend that they are derived from histiocytes – i.e. the RETICULO-ENDOTHELIAL SYSTEM.

Function The leucocytes constitute one of the most important of the defence mechanisms against infection. This applies particularly to the neutrophil leucocytes (see LEUCOCYTOSIS). (See also ABSCESS; BLOOD – Composition; INFLAMMATION; PHAGOCYTOSIS; WOUNDS.)... leucocytes

Macr-/macro

Pre?x denoting large-sized cell – for example, a MACROPHAGE is a large PHAGOCYTE.... macr-/macro

Pge

Short for Prostaglandin E, presumably the fifth subtype discovered, and usually separated into PGE1 and PGE2. These two, if made by the kidneys, slow sodium reabsorption; if within in the uterus, induce a stronger response to less stimulus; if made in the stomach lining inhibit gastric secretion; if secreted by macrophages, target tissues become more accessible to infiltration...and inflammation. These are the two prostaglandins whose levels are meant to be stabilized by gamma-linolenic acid (GLA) supplements. See PROSTAGLANDIN... pge

Phagocytosis

A process by which BACTERIA and other foreign particles in the body are ingested by monocytes in the blood and macrophages in the tissues (see under PHAGOCYTE) that envelop and digest bacteria, cells, cell debris and other small particles. Phagocytes are an essential part of the body’s defence mechanisms.... phagocytosis

Target Cell

Abnormal ERYTHROCYTES which are large and ‘?oppy’ and have a ringed appearance, similar to that of a target, when stained and viewed under the microscope. This change from normal may occur with iron-de?ciency ANAEMIA, liver disease, a small SPLEEN, haemoglobinopathies (disorders of HAEMOGLOBIN), and THALASSAEMIA.

A target cell is also a cell that is the focus of attack by macrophages (killer cells – see MACROPHAGE) or ANTIBODIES; it may also be the site of action of a speci?c hormone (see HORMONES).... target cell

Fever

Fever, or PYREXIA, is the abnormal rise in body TEMPERATURE that frequently accompanies disease in general.

Causes The cause of fever is the release of fever-producing proteins (pyrogens) by phagocytic cells called monocytes and macrophages, in response to a variety of infectious, immunological and neoplastic stimuli. The lymphocytes (see LYMPHOCYTE) play a part in fever production because they recognise the antigen and release substances called lymphokines which promote the production of endogenous pyrogen. The pyrogen then acts on the thermoregulatory centre in the HYPOTHALAMUS and this results in an increase in heat generation and a reduction in heat loss, resulting in a rise in body temperature.

The average temperature of the body in health ranges from 36·9 to 37·5 °C (98·4 to 99·5 °F). It is liable to slight variations from such causes as the ingestion of food, the amount of exercise, the menstrual cycle, and the temperature of the surrounding atmosphere. There are, moreover, certain appreciable daily variations, the lowest temperature being between the hours of 01.00 and 07.00 hours, and the highest between 16.00 and 21.00 hours, with tri?ing ?uctuations during these periods.

The development and maintenance of heat within the body depends upon the metabolic oxidation consequent on the changes continually taking place in the processes of nutrition. In health, this constant tissue disintegration is exactly counterbalanced by the consumption of food, whilst the uniform normal temperature is maintained by the adjustment of the heat developed, and of the processes of exhalation and cooling which take place, especially from the lungs and skin. During a fever this balance breaks down, the tissue waste being greatly in excess of the food supply. The body wastes rapidly, the loss to the system being chie?y in the form of nitrogen compounds (e.g. urea). In the early stage of fever a patient excretes about three times the amount of urea that he or she would excrete on the same diet when in health.

Fever is measured by how high the temperature rises above normal. At 41.1 °C (106 °F) the patient is in a dangerous state of hyperpyrexia (abnormally high temperature). If this persists for very long, the patient usually dies.

The body’s temperature will also rise if exposed for too long to a high ambient temperature. (See HEAT STROKE.)

Symptoms The onset of a fever is usually marked by a RIGOR, or shivering. The skin feels hot and dry, and the raised temperature will often be found to show daily variations – namely, an evening rise and a morning fall.

There is a relative increase in the pulse and breathing rates. The tongue is dry and furred; the thirst is intense, while the appetite is gone; the urine is scanty, of high speci?c gravity and containing a large quantity of solid matter, particularly urea. The patient will have a headache and sometimes nausea, and children may develop convulsions (see FEBRILE CONVULSION).

The fever falls by the occurrence of a CRISIS – that is, a sudden termination of the symptoms – or by a more gradual subsidence of the temperature, technically termed a lysis. If death ensues, this is due to failure of the vital centres in the brain or of the heart, as a result of either the infection or hyperpyrexia.

Treatment Fever is a symptom, and the correct treatment is therefore that of the underlying condition. Occasionally, however, it is also necessary to reduce the temperature by more direct methods: physical cooling by, for example, tepid sponging, and the use of antipyretic drugs such as aspirin or paracetamol.... fever

Matricaria Chamomilla

Linn.

Family: Compositae; Asteraceae.

Habitat: Native of Europe; grown in Jammu & Kashmir, Himachal Pradesh and Uttar Pradesh.

English: German Chamomile, Chamomile. German chamomile flower is equated with Matricaria recutita L. (synonym Chamomilla recutita L.) and Roman Chamomile flower with Anthemis nobilis L. (synonym Chamamaelum nobilis L.)

Unani: Baabunaa.

Action: Sedative, anticonvulsant, carminative, antispasmodic, analgesic, anti-inflammatory, antiseptic. See also Anthemis nobilis.

Key application (German Chamomile) ? In inflammatory diseases of the gastrointestinal tract and gastrointestinal spasm. Externally, in skin, mucous membrane and ano-genital inflammation and bacterial skin diseases. (German Commission E, The British Herbal Compendium.) As anti-inflammatory and anti- spasmodic. (The British Herbal Pharmacopoeia.)

The flowers of German chamomile gave volatile oil up to about 2%, containing alpha-bisabolol up to 50%, azu- lenes including chamazulene, guiazu- line and matricine; flavonoids including apigenin and luteolin and their glycosides, patuletin and quercetin; spiroethers; coumarins; polysaccha- rides.

The flowers are used as herbal tea for cough and cold and for promoting the flow of gastric secretion and bile. In chamomlile extracts, chamazulene has been found responsible for anti- inflammatory activity. Matricine and (-)-alpha-bisabolol also show anti- inflammatory and analgesic activity. Bisabolol exhibits ulceroprotective effect. Natural (-)-alpha-bisabolol has been shown to be significantly effective in healing burns; (-)-alpha-bisabolol, spiroethers and apigenin exhibit spasmolytic effect comparable with that of papaverine.

The polysaccharides are immunos- timulating and activate macrophages and B lymphocytes; play an important role in wound healing.

Crude aqueous extract of the plant has been reported to significantly delay the onset of convulsions and reduce mortality rate produced by picrotoxin experimentally.... matricaria chamomilla

Wbc

White Blood Cells, including those of innate immunity, including basophils, neutrophils, eosinophils, monocytes, macrophages (and others) and those of acquired immunity, the various types of lymphocytes. Also called leukocytes.... wbc

Lysozyme

An enzyme found in tears, saliva, sweat, nasal secretions, breast milk, and many tissues. It destroys bacteria by disrupting their cell walls.

macro- A prefix meaning large, as in macrophage (a large cell in the immune system) or macroglossia.... lysozyme

Nitric Oxide (no)

A naturally occurring chemical that performs a wide range of biological roles. It is involved in the laying down of memories in the BRAIN; in killing viruses, bacteria and cancer cells; and in helping to control blood pressure. NO, comprising a nitrogen atom attached to an oxygen one, is one of the smallest of biologically active compounds as well as having such diverse functions. The chemical is a muscle relaxant and is important in maintaining the heart and circulation in good condition. NO is also the toxic agent released by macrophages (see MACROPHAGE) to kill invading germs and spreading cancer cells. It acts as an essential NEUROTRANSMITTER and protects nerve cells against stress. Researchers are studying how it might be used to treat diseases, for example by using it as an inhaled gas in certain respiratory conditions.... nitric oxide (no)

Spleen

The large organ lying to the left of, below, and behind the stomach. This organ is partially responsible for white blood cell formation (red blood cells in childhood), and it is lined with resident macrophages that help it filter the blood, remove and recycle old and dead red blood cells, and send this all up to the liver in the portal blood. The liver, in fact, does most of the recycling of splenic hemoglobin derivatives. The spleen initiates much resistance and immunologic response, being made mostly of lymph pulp, and it stores and concentrates a large number of red blood cells. These can be injected into the bloodstream for immediate use under flight or fight stress, since the spleen is covered with capsule and vascular muscles that constrict in the presence of adrenalin or sympathetic adrenergic nerve stimulus.... spleen

Wigandia Caracasana

Kunth.

Family: Hydrophyllaceae.

Habitat: Native to tropical America; introduced into Indian gardens.

Action: Leaves and branch tips— a decoction is used in rheumatism; also for whooping cough and respiratory problems.

Solvent extracts of the leaves (etha- nol, acetone and M-hexane) were found active against Gram-positive bacteria.

Synonym: W. viridiflora Meissn. W. indica var. virdiflora Hook. f.

Family: Thymelaeaceae.

Habitat: Eastern Assam; as a weed in Tamil Nadu.

English: Small-Leaf Salago.

Folk: Salago.

Action: Root bark—diuretic, vesicant, purgative and piscicidal.

The root bark is reported to contain a flavone glycoside, wikstroemin, which exhibited diuretic activity.

In Chinese folk medicine, the bark is used for schistosomiasis.

The stem contains wikstromol, a lig- nin prototype which exhibited anti- neoplastic activity. Daphnoretin, isolated from the plant, caused platelet aggregation in the blood of rabbits. A polysaccharide, comprising glucose, arabinose, galacturonic acid, galactose and xylose, protected mice against radiation and enhanced the formation of macrophages.... wigandia caracasana

Anaemia, Haemolytic

A form of anaemia caused by premature destruction of red cells in the bloodstream (haemolysis). Haemolytic anaemias can be classified according to whether the cause of haemolysis is inside or outside the red cells.

When haemolysis is due to a defect inside the red cells, the underlying problem is abnormal rigidity of the cell membrane. This causes the cells to become trapped, at an early stage of their life-span, in the small blood vessels of the spleen, where they are destroyed by macrophages (cells that ingest foreign particles). Abnormal rigidity may result from an inherited defect of the cell membrane (as in hereditary spherocytosis), a defect of the haemoglobin in the cell (as in sickle-cell anaemia), or a defect of one of the cell’s enzymes. An inherited deficiency of the glucose-6phosphate dehydrogenase enzyme (see G6PD deficiency) may result in episodes of haemolytic anaemia since the red cells are prone to damage by infectious illness or certain drugs or foods.

Haemolytic anaemias due to defects outside the red cells fall into 3 main groups. First are disorders in which red cells are destroyed by buffeting (by artificial surfaces such as replacement heart valves, abnormal blood-vessel linings, or a blood clot in a vessel, for example). In the 2nd group, the red cells are destroyed by the immune system. Immune haemolytic anaemias may occur if foreign blood cells enter the bloodstream, as occurs in an incompatible blood transfusion, or they may be due to an autoimmune disorder. In haemolytic disease of the newborn, the baby’s red cells are destroyed by the mother’s antibodies crossing the placenta. Thirdly, the red cells may be destroyed by microorganisms; the most common cause is malaria. People with haemolytic anaemia may have symptoms common to all types of anaemia, such as fatigue and breathlessness, or symptoms specifically due to haemolysis, such as jaundice.

Diagnosis is made by examination of the blood (see blood film). Some inherited anaemias can be controlled by removing the spleen (see splenectomy). Others, such as G6PD deficiency, can be prevented by avoiding the drugs or foods that precipitate haemolysis. Anaemias due to immune processes can often be controlled by immunosuppressant drugs. Transfusions of red cells are sometimes needed for emergency treatment of life-threatening anaemia.... anaemia, haemolytic

Antigen-presenting Cell

(APC) a cell, such as a *dendritic cell or a *macrophage, that processes antigen for presentation to a T lymphocytes (see helper T cell).... antigen-presenting cell

Chronic

adj. 1. describing a disease of long duration involving very slow changes. Such a disease is often of gradual onset. The term does not imply anything about the severity of a disease. Compare acute. 2. describing a type of inflammation characterized by the presence of lymphocytes, plasma cells, and macrophages. —chronicity n.... chronic

Haemosiderin

n. an iron-storage compound found mainly in the cells of the *macrophage– *monocyte system in the marrow, in the *Kupffer cells of the liver, and in the spleen. It contains around 30% iron by weight.... haemosiderin

Lymph Node

A small organ lying along the course of a lymphatic vessel (see lymphatic system); commonly but incorrectly called a lymph gland. Lymph nodes vary considerably in size, from microscopic to about 2.5 cm (1 in) in diameter.

A lymph node consists of a thin, fibrous outer capsule and an inner mass of lymphoid tissue. Penetrating the capsule are several small lymphatic vessels (whichcarry lymph into the node). Each node contains sinuses (spaces), in which the lymph is filtered. The flow of the lymph slows as it moves through narrow channels in the sinuses; this reduction in flow allows macrophages (white blood cells that engulf and destroy foreign and dead material) time to filter microorganisms from the lymph. Germinal centres in the lymph node release white blood cells called lymphocytes, which also help to fight infection. A single, larger vessel carries lymph out of the node.... lymph node

Histiocyte

n. a fixed *macrophage, i.e. one that is stationary within connective tissue.... histiocyte

Histiocytoma

n. a tumour that contains *macrophages or *histiocytes, large cells with the ability to engulf foreign matter and bacteria. See also fibrosarcoma.... histiocytoma

Inflammation

n. the body’s response to injury, which may be acute or chronic. Acute inflammation is the immediate defensive reaction of tissue to any injury, which may be caused by infection, chemicals, or physical agents. It involves pain, heat, redness, swelling, and loss of function of the affected part. Blood vessels near the site of injury are dilated, so that blood flow is locally increased. White blood cells enter the tissue and begin to engulf bacteria and other foreign particles. Similar cells from the tissues (see macrophage) remove and consume the dead cells, sometimes with the production of pus, enabling the process of healing to commence. In certain circumstances healing does not occur and chronic inflammation ensues.... inflammation

Kupffer Cells

phagocytic cells that line the sinusoids of the *liver (see macrophage). They are particularly concerned with the formation of *bile and are often seen to contain fragments of red blood cells and pigment granules that are derived from the breakdown of haemoglobin. [K. W. von Kupffer (1829–1902), German anatomist]... kupffer cells

Leukotriene

n. one of a class of powerful chemical agents synthesized from arachidonic acid by mast cells, basophils, macrophages, and various other tissues. Leukotrienes are involved in inflammatory reactions and the immune response: they increase the permeability of small blood vessels, cause contraction of smooth muscle, and attract neutrophils to the site of an infection.... leukotriene

Malakoplakia

n. a rare form of chronic inflammatory disorder due to the defective destruction of phagocytosed bacteria. It is characterized by the formation of soft yellow plaques and nodules composed of foamy macrophages containing basophilic cytoplasmic inclusions (Michaelis–Gutmann bodies). Malakoplakia occurs most commonly in the urinary tract but can also occur in the skin.... malakoplakia

Microglia

n. one of the two basic classes of *glia (the non-nervous cells of the central nervous system), having a mainly scavenging function (see macrophage). Compare macroglia.... microglia

Reticuloendothelial System

(RES) a community of cells – *phagocytes – spread throughout the body. It includes *macrophages and *monocytes. The RES is concerned with defence against microbial infection and with the removal of worn-out blood cells from the bloodstream. See also spleen.... reticuloendothelial system

Tumour Necrosis Factor

(TNF) either of two proteins, TNF-? or TNF-?, that function as *cytokines. Produced by macrophages, monocytes, T lymphocytes, and various other cells, they mediate many responses, including inflammation, and have a marked action against tumour cells. Anti-TNF drugs (see cytokine inhibitor) are used in the treatment of several disorders, especially rheumatoid arthritis and ankylosing spondylitis.... tumour necrosis factor



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