Acute phase reaction
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Acute_phase_reaction".

Acute-phase proteins are a class of proteins whose plasma concentrations increase (positive acute phase proteins) or decrease (negative acute phase proteins) in response to inflammation. This response is called the acute-phase reaction (also called acute phase response).

Inflammatory cells and red blood cells
Inflammatory cells and red blood cells

In response to injury, local inflammatory cells (neutrophil granulocytes and macrophages) secrete a number of cytokines into the bloodstream, most notable of which are the interleukins IL-1, IL-6 and IL-8, and TNF-α.

The liver responds by producing a large number of acute-phase reactants. At the same time, the production of a number of other proteins is reduced; these are therefore referred to as "negative" acute phase reactants.

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Positive

Positive acute-phase proteins serve different physiological functions for the immune system. Some act to destroy or inhibit growth of microbes, e.g. C-reactive protein, Mannose-binding protein, complement factors, ferritin, ceruloplasmin, Serum amyloid A and haptoglobin. Others give negative feedback on the inflammatory response, e.g. serpins. Alpha 2-macroglobulin and coagulation factors affect coagulation.

"Positive" acute phase proteins:
Protein Immune system function
C-reactive protein Opsonin on microbes [1]
D-dimer protein fibrin degradation product
Mannose-binding protein Mannan-binding lectin pathway
Alpha 1-antitrypsin serpin, downregulates inflammation
Alpha 1-antichymotrypsin serpin, downregulates inflammation
Alpha 2-macroglobulin
Fibrinogen, prothrombin, factor VIII, von Willebrand factor, plasminogen coagulation factors
Complement factors Complement system
Ferritin Binding iron, inhibiting microbe iron uptake
Serum amyloid P component (see amyloid)
Serum amyloid A
Ceruloplasmin Oxidizes iron, facilitating for ferritin, inhibiting microbe iron uptake
Haptoglobin Bind hemoglobin, inhibiting microbe iron uptake

Negative

"Negative" acute phase proteins:
Protein Immune system function of decrease
Albumin [3]
Transferrin [3]
Transthyretin [3]
Transcortin Decreased binding of cortisol, upregulation of inflammation
Retinol binding protein

Clinical significance

Further information: Reference_ranges_for_blood_tests#Immunology

Measurement of acute phase proteins, especially C-reactive protein, is a useful marker of inflammation in both medical and veterinary clinical pathology. It correlates with the erythrocyte sedimentation rate (ESR).

They may also indicate liver failure [4]

References

  1. ^ Lippincott's Illustrated Reviews: Immunology. Paperback: 384 pages. Publisher: Lippincott Williams & Wilkins; (July 1, 2007). Language: English. ISBN-10: 0781795435. ISBN-13: 978-0781795432. Page 182
  2. ^ Boer JP, Creasey AA, Chang A, Abbink JJ, et al. (1993) "Alpha-2-macroglobulin functions as an inhibitor of fibrinolytic, clotting, and neutrophilic proteinases in sepsis: studies using a baboon model." Infect Immun. 61(12): 5035–5043.
  3. ^ a b c Ritchie RF, Palomaki GE, Neveux LM, Navolotskaia O, Ledue TB, Craig WY (1999). "Reference distributions for the negative acute-phase serum proteins, albumin, transferrin and transthyretin: a practical, simple and clinically relevant approach in a large cohort". J. Clin. Lab. Anal. 13 (6): 273–9. PMID 10633294. 
  4. ^ Ananian P, Hardwigsen J, Bernard D, Le Treut YP (2005). "Serum acute-phase protein level as indicator for liver failure after liver resection". Hepatogastroenterology 52 (63): 857–61. PMID 15966220. 

See also

External links

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Acute phase proteins
Amyloid
Other positive
Negative
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