acute phase reaction

a·cute phase re·ac·tion

to the changes in synthesis of certain proteins within the serum during an inflammatory response; this response provides rapid protection for the host against microorganisms through nonspecific defense mechanisms.

Acute Phase Response

A constellation of nonspecific host responses to cytokines* released in response to tissue injury, infection, inflammation and rarely malignancy—e.g., Hodgkin lymphoma, renal cell carcinoma—which causes functional liver changes—increased synthesis of acute phase proteins (endocrine system), abnormal glucose tolerance, increased gluconeogenesis, thyroid dysfunction, altered lipid metabolism (immune system), left shift leukocytosis, hypergammaglobulinaemia (metabolic system), decreased albumin synthesis, energy consumption, increased ceruloplasmin, reduced iron and zinc levels, and CNS (lethargy); the most measured molecule in the response is the highly nonspecific CRP, which may increase 10- to 1000-fold within hours from a normal level of 100 µg/L.
*Biological response modifiers—e.g., IL-1alpha, IL-6, TNF-alpha, TGF-beta-1, and interferons; intercellular communication is mediated by either direct cell-to-cell contact, or by soluble signalling molecules including hormones, eicosanoids, neurotransmitters, and to cytokines, which may play the most central role in inducing the APR; other molecules involved in the APR include corticosteroids, insulin, thrombin, histamine, and others; screening tests for the APR include erythrocyte sedimentation rate, plasma viscosity, and zeta sedimentation ratio.

a·cute phase re·ac·tion

(ă-kyūt' fāz rē-ak'shŭn)
Refers to the changes in synthesis on certain proteins within the serum during an inflammatory response; this response provides rapid protection for the host against microorganisms via nonspecific defense mechanisms.
Synonym(s): acute phase response.

acute phase reaction

The release of physiologically active proteins by the liver into the blood in response to interleukin-6 or other cytokines that participate in the destruction of pathogens and promote healing during inflammation. This results in fever, an increase in circulating neutrophils, and activation of the hypothalamus, pituitary gland, and adrenal glands. The acute phase response involves the production of plasma proteins as well as other metabolic, hematological, and neuroendocrine events. Cytokines, produced by white blood cells, esp. macrophages, stimulate the liver's production of acute phase proteins: interleukin-6, interleukin-1ß, tumor necrosis factor a, interferon-?, and transforming growth factor ß. These proteins, which increase or decrease in the blood by at least 25%, include C-reactive protein, complement, and coagulation factors; they enhance the immune response and tissue repair. Cytokines also stimulate systemic changes, producing diverse beneficial effects including fever, which enhances the immune response and stabilizes cell membranes; increased adrenal cortisol and catecholamine production, which helps maintain hemodynamic stability; thrombocytosis and leukocytosis; and increased gluconeogenesis and lipolysis, which provide nutrients for cells. There are also negative effects, however, including decreased production of erythropoietin, causing anemia; impaired growth; anorexia; lethargy; and, if prolonged, the loss of skeletal muscle and fat (cachexia).
Synonym: acute phase response. See: cytokine; inflammation; interleukin-6; protein, acute phase
References in periodicals archive ?
An acute phase reaction is a side effect of intravenous bisphosphonate use.
The principal action of bisphosphonates is inhibition of osteoclastic bone resorption, but the potent nitrogen-containing aminobisphosphonates such as zoledronic acid, alendronate, pamidronate, rise-dronate, and ibandronate also have proinflammatory effects, with an acute phase reaction characterized by fever and flulike symptoms occurring following a first treatment with these drugs in more than one-third of patients (Clin.
Determination of serum acute phase reaction protein in patients with severe acute respiratory syndrome.
Signs and symptoms of an acute phase reaction occurred in some patients in the first 3 days after the zoledronic acid infusion.
To examine the relationship between acute phase reaction and total transcobalamin, we analyzed plasma samples from 59 patients with various concentrations of C-reactive protein (reference interval, <40 nmol/ L).
IL-6 is a cytokine that plays important roles in host defense, acute phase reactions, immune response and hematopoiesis (production of all types of blood cells).

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