Show Summary Details
Page of

The acute phase response and C-reactive protein 

The acute phase response and C-reactive protein

The acute phase response and C-reactive protein

M.B. Pepys


February 27, 2014: This chapter has been re-evaluated and remains up-to-date. No changes have been necessary.


Discussion of lack of utility of CRP measurements in risk assessment for cardiovascular disease.

Updated on 28 Nov 2013. The previous version of this content can be found here.
Page of

PRINTED FROM OXFORD MEDICINE ONLINE ( © Oxford University Press, 2015. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy).

date: 23 April 2017

The acute phase response—trauma, tissue necrosis, infection, inflammation, and malignant neoplasia induce a complex series of nonspecific systemic, physiological, and metabolic responses including fever, leucocytosis, catabolism of muscle proteins, greatly increased de novo synthesis and secretion of a number of ‘acute phase’ plasma proteins, and decreased synthesis of albumin, transthyretin, and high- and low-density lipoproteins. The altered plasma protein concentration profile is called the acute phase response. All endothermic animals mount a similar response, suggesting that it may have survival value, and increased availability of proteinase inhibitors, complement, clotting, and transport proteins presumably enhances host resistance, minimizes tissue injury, and promotes regeneration and repair.

Acute phase proteins—these are mostly synthesized by hepatocytes, in which transcription is controlled by cytokines including interleukin 1, interleukin 6, and tumour necrosis factor. The circulating concentrations of complement proteins and clotting factors increase by up to 50 to 100%; some of the proteinase inhibitors and α‎1-acid glycoprotein can increase three- to fivefold; but C-reactive protein and serum amyloid A protein (an apolipoprotein of high-density lipoprotein particles) are unique in that their concentrations can change by more than 1000-fold.

C-reactive protein (CRP)—this consists of five identical, nonglycosylated, noncovalently-associated polypeptide subunits. It binds to substances which contain phosphocholine, including phospholipids, some plasma lipoproteins, and the plasma membranes of damaged cells, also to small nuclear ribonucleoprotein particles when these are exposed in dead or damaged cells. By activating the classical complement pathway after binding to ligand it can trigger the inflammatory, opsonizing, and complex-solubilizing activities of the complement system, perhaps thereby protecting against infection with organisms that express phosphocholine (e.g. pneumococci and Haemophilus influenzae) and aiding in recognition and ‘scavenging’ of cellular debris.

Clinical features—(1) determination of CRP in serum or plasma is the most useful marker of the acute phase response in most inflammatory and tissue damaging conditions. It is a stable analyte, easy to measure, and has proven value in monitoring therapeutic responses. (2) Acute phase proteins may be harmful in some circumstances. Sustained increased production of serum amyloid A protein can lead to the deposition of AA-type, reactive systemic amyloid, a serious and usually fatal condition that can complicate chronic infective and inflammatory diseases. CRP, through its capacity to activate complement, can exacerbate ischaemic (and possibly also other forms) of tissue damage.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.