mononuclear

• adj.

• 単核の

　

WordNet

1. having only one nucleus (同)mononucleate

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/01/16 16:41:16」(JST)

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Monocyte
monocytes under a light microscope from a peripheral blood smear surrounded by red blood cells
Details
Latin	monocytus
Identifiers
Code	TH H2.00.04.1.02010
Anatomical terminology

3D Rendering of a Monocyte

Monocytes are a type of white blood cells (leukocytes). They are the largest of all leukocytes. They are part of the innate immune system of vertebrates including all mammals (humans included), birds, reptiles, and fish. They are amoeboid in shape, having agranulated cytoplasm. Monocytes have unilobar nuclei, which makes them one of the types of mononuclear leukocytes (containing azurophil granules). The archetypal idea of the nucleus is that it is bean-shaped or kidney-shaped, although the most important distinction is that it is not deeply furcated into lobes, as occurs in polymorphonuclear leukocytes. Monocytes constitute 2% to 10% of all leukocytes in the human body. They play multiple roles in immune function. Such roles include: (1) replenishing resident macrophages under normal states, and (2) in response to inflammation signals, monocytes can move quickly (approx. 8–12 hours) to sites of infection in the tissues and divide/differentiate into macrophages and dendritic cells to elicit an immune response. Half of them are stored in the spleen. Monocytes are usually identified in stained smears by their large kidney shaped or notched nucleus. These change into macrophages after entering into the tissue spaces, and in endothelium can transform into foam cells.

Physiology

Monocytes are produced by the bone marrow from precursors called monoblasts, bipotent cells that differentiated from hematopoietic stem cells. Monocytes circulate in the bloodstream for about one to three days and then typically move into tissues throughout the body. They constitute between three to eight percent of the leukocytes in the blood. Half of them are stored as a reserve in the spleen in clusters in the red pulp's Cords of Billroth. In the tissues, monocytes mature into different types of macrophages at different anatomical locations. Monocytes are the largest corpuscles in the blood.

Monocytes which migrate from the bloodstream to other tissues will then differentiate into tissue resident macrophages or dendritic cells. Macrophages are responsible for protecting tissues from foreign substances, but are also suspected to be important in the formation of important organs like the heart and brain. They are cells that possess a large smooth nucleus, a large area of cytoplasm, and many internal vesicles for processing foreign material.

Monocytes and their macrophage and dendritic-cell progeny serve three main functions in the immune system. These are phagocytosis, antigen presentation, and cytokine production. Phagocytosis is the process of uptake of microbes and particles followed by digestion and destruction of this material. Monocytes can perform phagocytosis using intermediary (opsonising) proteins such as antibodies or complement that coat the pathogen, as well as by binding to the microbe directly via pattern-recognition receptors that recognize pathogens. Monocytes are also capable of killing infected host cells via antibody-dependent cell-mediated cytotoxicity. Vacuolization may be present in a cell that has recently phagocytized foreign matter.

Many factors produced by other cells can regulate the chemotaxis and other functions of monocytes. These factors include most particularly chemokines such as monocyte chemotactic protein-1 and monocyte chemotactic protein-3; certain arachidonic acid metabolites such as Leukotriene B4 and members of the 5-Hydroxyicosatetraenoic acid and 5-oxo-eicosatetraenoic acid family of OXE1 receptor agonists (e.g., 5-HETE and 5-oxo-ETE); and N-Formylmethionine leucyl-phenylalanine and other N-formylated oligopeptides which are made by bacteria and activate the formyl peptide receptor 1.

Microbial fragments that remain after such digestion can serve as antigens. The fragments can be incorporated into MHC molecules and then trafficked to the cell surface of monocytes (and macrophages and dendritic cells). This process is called antigen presentation and it leads to activation of T lymphocytes, which then mount a specific immune response against the antigen.

Other microbial products can directly activate monocytes and this leads to production of pro-inflammatory and, with some delay, of anti-inflammatory cytokines. Typical cytokines produced by monocytes are TNF, IL-1, and IL-12.

Monocyte subpopulations

There are at least three types of monocytes in human blood:

1. The classical monocyte is characterized by high level expression of the CD14 cell surface receptor (CD14++ CD16- monocyte)
2. The non-classical monocyte shows low level expression of CD14 and additional co-expression of the CD16 receptor (CD14+CD16++ monocyte).
3. The intermediate monocyte with high level expression of CD14 and low level expression of CD16 (CD14++CD16+ monocytes).

Ghattas et al. state that the "intermediate" monocyte population is likely to be a unique subpopulation of monocytes, as opposed to a developmental step, due to their comparatively high expression of surface receptors involved in reparative processes(including vascular endothelial growth factors type 1 and 2, CXCR4, and Tie-2) as well as evidence that the "intermediate" subset is specifically enriched in the bone marrow. After stimulation with microbial products the CD14+CD16++ monocytes produce high amounts of pro-inflammatory cytokines like tumor necrosis factor and interleukin-12.

Said et al. showed that activated monocytes express high levels of PD-1 which might explain the higher expression of PD-1 in CD14+CD16++ monocytes as compared to CD14++CD16- monocytes. Triggering monocytes-expressed PD-1 by its ligand PD-L1 induces IL-10 production which activates CD4 Th2 cells and inhibits CD4 Th1 cell function.

Diagnostic use

A scanning electron microscope (SEM) image of normal circulating human blood. One can see red blood cells, several knobby white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets.

A monocyte count is part of a complete blood count and is expressed either as a ratio of monocytes to the total number of white blood cells counted, or by absolute numbers. Both may be useful in determining or refuting a possible diagnosis.

Monocytosis

Monocytosis is the state of excess monocytes in the peripheral blood. It may be indicative of various disease states. Examples of processes that can increase a monocyte count include:

• chronic inflammation
• stress response
• Cushing's syndrome (hyperadrenocorticism)
• immune-mediated disease
• pyogranulomatous disease
• necrosis
• red blood cell regeneration
• Viral fever
• sarcoidosis

A high count of CD14+CD16++ monocytes is found in severe infection (sepsis) and a very low count of these cells is found after therapy with immuno-suppressive glucocorticoids.

Monocytopenia

Monocytopenia is a form of leukopenia associated with a deficiency of monocytes.

Dendritic cells

Monocytes can be used to generate dendritic cells in vitro by adding cytokines like Granulocyte Monocyte Colony Stimulating Factor (GM-CSF) and IL-4.

Blood content

Reference ranges for blood tests of white blood cells, comparing monocyte amount (shown in green) with other cells.

See also

• Agranulocyte
• Complete blood count
• Hematopoiesis
• Lymphocyte
• Neutrophil granulocyte
• Phagocyte
• White blood cell

References

External links

• Histology image: 01702ooa – Histology Learning System at Boston University
• Human Monocytes — Prof. Dr. Ziegler-Heitbrock
• Circulation of Body Fluids

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English Journal

• Experimental Autoimmune Encephalomyelitis in Marmosets.

• Jagessar SA1, Dijkman K, Dunham J, 't Hart BA, Kap YS.
• Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2016;1304:171-86. doi: 10.1007/7651_2014_113.
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• PMID 25208751

• ELISPOT Techniques.

• Ji N1, Forsthuber TG.
• Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2016;1304:63-71. doi: 10.1007/7651_2014_111.
• The enzyme-linked immunospot (ELISPOT) assay is a widely used method for enumerating antigen-specific cytokine-producing or antibody-secreting immune cells. It is one of the most effective immunological and diagnostic approaches to detect and quantify low-frequency cytokine- or antibody-producing ce
• PMID 25117217

• Peripheral Blood Mononuclear Cells: Isolation, Freezing, Thawing, and Culture.

• Riedhammer C1, Halbritter D, Weissert R.
• Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2016;1304:53-61. doi: 10.1007/7651_2014_99.
• The work with peripheral blood mononuclear cells (PBMCs), which comprise lymphocytes and monocytes, is indispensable in immunological diagnostics and research. The isolation of PBMCs takes advantage of differences in cell density of the different blood components. Density gradient centrifugation of
• PMID 25092056

Japanese Journal

• The effects of carboxymethyl chitosan on the regulation of the proliferation, differentiation and cytokine expression of peripheral blood mononuclear cells

• Xu Wenhua,Han Baoqin,Liang Yee 他
• Polymer journal 45(2), 226-232, 2013-02-00
• NAID 40019560431

• Impact of Solute Carrier Family 29 Member 1 (SLC29A1) Single Nucleotide Polymorphisms on mRNA Expression in Peripheral Blood Mononuclear Cells

• Suzuki Yoshiharu,Homma Masato,Abei Masato 他
• Biological & pharmaceutical bulletin 36(1), 144-146, 2013-01-00
• NAID 40019536224

Related Links

• mononuclearの意味・用例｜英辞郎 on the WEB：アルク

mononuclear 【名】単核細胞 【形】 〔細胞が〕単核の 《化学》単環（式）の 【... - アルクがお届けする進化するオンライン英和・和英辞書データベース。一般的な単語や連語から、イディオム、専門用語、スラングまで幅広く収録。

• Mononuclear | definition of mononuclear by Medical dictionary

mononuclear [mon″o-noo´kle-ar] having only one nucleus. mon·o·nu·cle·ar (mon'ō-nū'klē-ăr), Having only one nucleus; used especially in reference to phagocytic cells. mononuclear /mono·nu·cle·ar/ (-noo´kle-er) 1. having but one ...

Related Pictures

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★リンクテーブル★

拡張検索	「mononuclear leukocyte」「peripheral blood mononuclear cell」

「mononuclear leukocyte」

　　[★]

• 単核白血球、単核球

関

monocyte

「peripheral blood mononuclear cell」

　　[★]

• 末梢血単核球

関

PBMC