Mononuclear phagocyte system
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reticuloendothelial system
(rə¦tik·yə·lō′en·dō′thē·lē·əl ′sis·təm)
(anatomy) The macrophage system, including all phagocytic cells such as histiocytes, macrophages, reticular cells, monocytes, and microglia, except the granular white blood cells. Abbreviated RES. Also known as hematopoietic system; reticular system.
Britannica Concise Encyclopedia:
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reticuloendothelial system
Part of the body's defenses, consisting of a class of cells widely distributed in the body. Reticuloendothelial cells filter out and destroy bacteria, viruses, and foreign substances and destroy worn-out or abnormal cells and tissues. Precursor cells in bone marrow develop into monocytes ( leukocyte), which are released into the bloodstream. Most enter body tissues, developing into much larger cells called macrophages, with different appearances in various locations. Some roam through the circulation and between cells and can coalesce into a single cell around a foreign object to engulf it. Reticuloendothelial cells also interact with lymphocytes in immune reactions. Cells in the spleen destroy old red blood cells and recycle their hemoglobin; uncontrolled, this process causes anemia. Tumours of the reticuloendothelial system can be localized or widespread throughout the body. lymphatic system.
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American Heritage Stedman's Medical Dictionary:
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reticuloendothelial system
Saunders Veterinary Dictionary:
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reticuloendothelial system
A term that encompasses the monocyte–macrophage or mononuclear phagocytic system and also includes reticulum cells. It consists of a population of cells called macrophages, which are of bone marrow origin and are widely distributed throughout the body. Immature macrophages or monocytes make up about 5% of peripheral blood leukocytes. Mature macrophages are found in connective tissue (histiocytes), lining hepatic sinusoids (Kupffer cells), in the lung (alveolar macrophages), brain (microglia) and skin (Langerhans cells). They are also found in the spleen, lymph nodes and bone marrow. The major roles of these cells include: phagocytosis, antigen-processing and trapping, regulation of immune responses and the secretion of several biologically important factors such as interleukin 1, lysozyme, plasminogen activator and complement components.
The macrophages of the spleen possess the ability to dispose of disintegrated erythrocytes. They do not, however, destroy hemoglobin, which is liberated in the process.
Kupffer cells, together with the cells of the general connective tissue and bone marrow, are capable of transforming into bile pigment the hemoglobin released by disintegrated erythrocytes.
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Mononuclear phagocyte system
The mononuclear phagocyte system (MPS) is a part of the immune system that consists of the phagocytic cells[1] 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.
"Reticuloendothelial system" is an older term for the mononuclear phagocyte system, but it is used less commonly now, as it is understood that most endothelial cells are not macrophages.[2]
The spleen is the largest unit of the mononuclear phagocyte system. The monocyte is formed in the bone marrow and transported by the blood; it migrates into the tissues, where it transforms into a histiocyte or a macrophage. Macrophages are diffusely scattered in the connective tissue and in liver (Kupffer cells), spleen and lymph nodes (sinus histiocytes), lungs (alveolar macrophages), and central nervous system (microglia). The half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years. The mononuclear phagocyte system is part of both humoral and cell-mediated immunity. The mononuclear phagocyte system has an important role in defense against microorganisms, including mycobacteria, fungi, bacteria, protozoa, and viruses. Macrophages remove senescent erythrocytes, leukocytes, and megakaryocytes by phagocytosis and digestion.
Functions
- Formation of new red blood cells (RBCs) and white blood cells (WBCs).
- Destruction of old RBCs and WBCs
- Formation of antibody.
- Formation of plasma proteins.
- Formation of bile pigments.
References
- ^ MeSH Mononuclear+Phagocyte+System
- ^ Inderbir Singh (2006). Textbook of human histology. Jaypee Brothers Publishers. pp. 90–. ISBN 978-81-8061-809-3. http://books.google.com/books?id=Ej22iANgNkoC&pg=PA90. Retrieved 12 November 2010.
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McGraw-Hill Science & Technology Dictionary
McGraw-Hill Dictionary of Scientific and Technical Terms. Copyright © 2003, 1994, 1989, 1984, 1978, 1976, 1974 by McGraw-Hill Companies, Inc. All rights reserved.
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Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
American Heritage Stedman's Medical Dictionary
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.
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Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
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