Endogenous pyrogens

The inherent mechanism that prevents the height of fever from reaching a potentially dangerous level. It is mediated by substances liberated both systemically and within the brain during fever that counter the formation or action of endogenous pyrogens, or inhibit the activity of neural circuits that modulate febrigenesis. 

A class of immunoregulatory polypeptides produced by various cells types, but predominantly by mononuclear phagocytes activated by signals provided by exogenous pyrogens. These peptides act as endogenous pyrogens. 

Fever is the most common manifestation. The thermoregulatory centre in the hypothalamus regulates body temperature and this can be affected by endotoxins (heat-stable lipopolysaccharides) of Gram-negative bacteria and also by a monokine secreted by monocytes and macrophages called interleukin-1 (IL-1) which is also termed endogenous pyrogen. Antibody production and T-cell proliferation have been shown to be enhanced at elevated body temperatures and thus are beneficial effects of fever. 

Sleep-promoting effects of endogenous pyrogen (interleukin-1). Am. J. Physiol. 

In many instances the influence of pyrogens on body temperature is indirect. For example, entry of endotoxin into the bloodstream stimulates the production of IL-1 (Chapter 9) by macrophages. It is the IL-1 that directly initiates the fever response (hence its alternative name, endogenous pyrogen ). 

As a consequence of the various approaches adopted in naming and classifying cytokines, it is hardly surprising to note that many are known by more that one name. IL-1, for example, is also known as lymphocyte activating factor (LAF), endogenous pyrogen, leukocyte endogenous mediator, catabolin and mononuclear cell factor. This has led to even further confusion in this field. 

IL-l is also known as lymphocyte-activating factor (LAF), endogenous pyrogen and catabolin. It displays a wide variety of biological activities and has been appraised clinically in several trials. 

The action of endogenous pyrogens on the hypothalamus produces fever, because of a readjustment ill the central set point controlling the body s internal temperature. Salicylates and other NSAIDs achieve their antipyretic effect by controlling the prostaglandin-induced release of pyrogens. 

Van Damme J, De Ley M, Opdenakker G, Billiau A, et al. 1985. Homogenous interferon-inducing 22 K factor is related to endogenous pyrogen and interleukin-1. Nature. 314 266-268. 

Krueger JM, Walter J, Dinarello CA, Wolff SM, Chedid L. Sleep-promoting effects of endogenous pyrogen (interleukin-1). Am J Physiol 1984 246 R994—R999. 

Endogenous pyrogens (and exogenous pyrogens that have their effects through the endogenous group) induce the hypothalamic vascular endothelium to produce... 

Early-phase proinflammatory cytokines (endogenous pyrogens) Interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-a)... 

Interleukin 1 (IL-1) Endogenous pyrogen Monocytes/macs Th cells stimulates production of lymphokines, especially IL-2 and expression of IL-2R B cells proliferation and differentiation Macs stimulates production of cytokines, IL-1, IL-6, and tumor necrosis factor-a (TNF-a) Brain fever response... 

Encron rizolipasc. endogenous pyrogen > interleukin-1. ENDOPEPTIDASE INHIBITORS act at one or other of the endopeptidase enzymes that cleave the C-terminal residue from oligopeptides or proteins (thus are stricdy proteinases). They can be divided into classes on the basis of their functional characteristics. These classes are dealt with separately in terms of their alternate names, notable substrates and inhibitors. They often act along with ectopeptidases - the carboxypeptidases and amino-peptidases. Endopeptidase inhibitors contain members of the metalloproteinase and serine protease families. Some are important neuropeptidases - concerned with degradation of... 

In common with IL-1 and TNF, IL-6 has a role as an endogenous pyrogen, inducing fever. It was suggested that central IL-6 is a necessary component of the fever response to both endogenous (IL-lp) and exogenous (LPS) pyrogens in mice and that IL-6 acts downstream from both peripheral and central IL-ip. °... 

Acting as an endogenous pyrogen (shared with IL-1) and mediated by increased synthesis of PGs... 

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