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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/08/26 12:07:23」(JST)

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Anaphylatoxins, or complement peptides, are fragments (C3a, C4a and C5a) that are produced as part of the activation of the complement system.^[2] Complement components C3, C4 and C5 are large glycoproteins that have important functions in the immune response and host defense.^[3] They have a wide variety of biological activities and are proteolytically activated by cleavage at a specific site, forming a- and b-fragments.^[4] A-fragments form distinct structural domains of approximately 76 amino acids, coded for by a single exon within the complement protein gene. The C3a, C4a and C5a components are referred to as anaphylatoxins:^[4]^[5] they cause smooth muscle contraction, histamine release from mast cells, and enhanced vascular permeability.^[5] They also mediate chemotaxis, inflammation, and generation of cytotoxic oxygen radicals.^[5] The proteins are highly hydrophilic, with a mainly alpha-helical structure held together by 3 disulfide bridges.^[5]

Function

Anaphylatoxins are able to trigger degranulation (release of substances) of endothelial cells, mast cells or phagocytes, which produce a local inflammatory response. If the degranulation is widespread, it can cause a shock-like syndrome similar to that of an allergic reaction.

Anaphylatoxins indirectly mediate:

smooth muscle cells contraction, for example bronchospasms
increase in the permeability of blood capillaries
chemotaxis — receptor-mediated movement of leukocytes in the direction of the increasing concentration of anaphylatoxins

Examples

Important anaphylatoxins:

C5a has the highest specific biological activity and is able to act directly on neutrophils and monocytes to speed up the phagocytosis of pathogens.
C3a works with C5a to activate mast cells, recruit antibody, complement and phagocytic cells and increase fluid in the tissue, all of which contribute to the initiation of the adaptive immune response.
C4a is the least active anaphylatoxin.

Terminology

Although some drugs (morphine, codeine, synthetic ACTH) and some neurotransmitters (norepinephrine, substance P) are important mediators of degranulation of mast cells or basophils, they are generally not called anaphylatoxins. This term is reserved only for fragments of the complement system.

Human proteins containing this domain

C3, C4A, C4B, C4B-1, C5, FBLN1, FBLN2

References

^ Williamson, Michael P.; Madison, Vincent S. (1990). "Three-dimensional structure of porcine C5ades Arg from proton nuclear magnetic resonance data". Biochemistry. 29 (12): 2895–905. PMID 2337573. doi:10.1021/bi00464a002.
^ Hugli, T. E. (1986). "Biochemistry and biology of anaphylatoxins". Complement. 3 (3): 111–27. PMID 3542363.
^ Fritzinger, D. C.; Petrella, E. C.; Connelly, M. B.; Bredehorst, R; Vogel, C. W. (1992). "Primary structure of cobra complement component C3". Journal of immunology. 149 (11): 3554–62. PMID 1431125.
^ ^a ^b Ogata, R. T.; Rosa, P. A.; Zepf, N. E. (1989). "Sequence of the gene for murine complement component C4". The Journal of Biological Chemistry. 264 (28): 16565–72. PMID 2777798.
^ ^a ^b ^c ^d Gennaro, Renato; Simonic, Tatjana; Negri, Armando; Mottola, Cristina; Secchi, Camillo; Ronchi, Severino; Romeo, Domenico (1986). "C5a fragment of bovine complement. Purification, bioassays, amino-acid sequence and other structural studies". European Journal of Biochemistry. 155 (1): 77–86. PMID 3081348. doi:10.1111/j.1432-1033.1986.tb09460.x.

External links

Anaphylatoxin at the US National Library of Medicine Medical Subject Headings (MeSH)

This article incorporates text from the public domain Pfam and InterPro IPR000020

UpToDate Contents

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1. 補体経路 complement pathways
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3. 補体系の概要および臨床的評価 overview and clinical assessment of the complement system
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5. 予防接種に対するアレルギー反応 allergic reactions to vaccines

English Journal

Complement in pregnancy: a delicate balance.

Denny KJ, Woodruff TM, Taylor SM, Callaway LK.SourceSchool of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia; School of Medicine, The University of Queensland, Brisbane, QLD, Australia.
American journal of reproductive immunology (New York, N.Y. : 1989).Am J Reprod Immunol.2013 Jan;69(1):3-11. doi: 10.1111/aji.12000. Epub 2012 Aug 27.
The complement system is a key component of innate host defence that, under normal conditions, is responsible for the opsonization and destruction of potential pathogens. However, inappropriate or excessive activation of complement can have a detrimental effect on the host and has been implicated in
PMID 22925193

Barrier modulation in drug delivery to the retina.

Campbell M, Humphries MM, Humphries P.SourceOcular Genetics Unit, Department of Genetics, Trinity College, Dublin, Ireland, Matthew.Campbell@tcd.ie.
Methods in molecular biology (Clifton, N.J.).Methods Mol Biol.2013;935:371-80. doi: 10.1007/978-1-62703-080-9_26.
The inner blood-retina barrier (iBRB) is essential in restricting the movement of systemic components such as enzymes, anaphylatoxins, or pathogens that could otherwise enter the neural retina and cause extensive damage. The barrier has evolved to confer protection to the delicate microenvironment o
PMID 23150382

Japanese Journal

Complement inhibition alleviates paraquat-induced acute lung injury

WANG Han Bin
日本毒性学会学術年会 39.2(0), AS1-2, 2012
… Expression of the anaphylatoxin receptors, C3aR and C5aR, was also increased. …
NAID 130005009266

抗C4抗体を有し新鮮凍結血漿の投与でアナフィラキシー様反応を来した1例

鬼松幸子,内田立身,氏家知佳,山本直子,舩本康申,小河敏伸,本田豊彦
日本輸血細胞治療学会誌 58(6), 760-764, 2012
新鮮凍結血漿（Fresh Frozen Plasma：FFP）の投与によりアナフィラキシー様反応を来し，検索の結果，抗C4抗体（IgGクラス）が関与した可能性が示唆された症例を経験した．さらに本例では輸血後にトリプターゼ値上昇，好酸球増多がありIgE値が高く，好酸球・好塩基球・肥満細胞の脱顆粒により生じたmediatorによるアナフィラキシー様反応を起こした可能性も示唆された．症例は79歳男性， …
NAID 130004542677

マスト細胞の補体による活性化 (特集マスト細胞活性化の関与因子)

澤向範文,湯川宗乃助,田中良哉
臨床免疫・アレルギー科 55(6), 608-611, 2011-06
NAID 40018904438

Related Pictures

★リンクテーブル★

リンク元	「C3a」「アナフィラトキシン」
拡張検索	「anaphylatoxin C5a receptor」「anaphylatoxin inactivator」

「C3a」

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

Anaphylotoxin-like domain
	Structure of porcine C5adesArg.
Identifiers
Symbol	ANATO
Pfam	PF01821
InterPro	IPR000020
SMART	ANATO
PROSITE	PDOC00906
SCOP	1c5a
SUPERFAMILY	1c5a
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary