[With reference to the article "Pyrogenic activity in sera of febrile patients mediated by endogenous pyrogen and activators of adenylate cyclase"].
Explore the source record for details and available documents.
Retraction Notice↗
SEARCH · Search PubMed
Results for “PYROGENS”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Human leukocytic pyrogen: purification and development of a radioimmunoassay.
Leukocytic pyrogen is a small endogenous protein that mediates fever. Because of the limitations of bioassays, circulating leukocytic pyrogen has not been demonstrated during fever in humans. The pyrogen was produced in vitro after phagocytosis of staphylococci by blood monocytes. Antibody against the pyrogen was obtained from rabbits immunized with leukocytic pyrogen and the antiserum was purified by solid-phase immunoadsorbants. Purified antibody to the pyrogen was attached to activated Sepharose 4B and used in conjunction with gel filtration to purify the pyrogen. The pyrogen was labeled with 125I and further purified by gel filtration and ion-exchange chromatography. The final preparation of 125I-labeled pyrogen demonstrated a homogeneous band during isoelectric focusing and other separation procedures. With antibody to pyrogen attached to Sepharose, less than 0.1 of a rabbit pyrogenic dose of human leukocytic pyrogen inhibited the binding of 125I-labeled pyrogen to this immunoadsorbant, and this inhibition was not affected by the presence of human serum. Thus, a radioimmunoassay for human leukocytic pyrogen has been developed that may be used to detect circulating pyrogen during fever in humans.
Antibodies↗
Influenza virus pyrogenicity: central role of structural orientation of virion components and involvement of viral lipid and glycoproteins.
Ultraviolet light-inactivated, non-infectious influenza virus is pyrogenic; virion components are probably responsible for this pyrogenicity. To try to identify the pyrogenic component, influenza virions were disrupted with either bromelain or sodium deoxycholate (DOC). Treatment of infectious virions with bromelain, under conditions that removed the surface glycoproteins (spikes), destroyed their pyrogenicity. The supernatant, containing non-aggregated and modified glycoproteins, was also non-pyrogenic. Disruption of virions with DOC considerably reduced pyrogenicity; however, some was retained by the sub-viral cores. Viral nucleoprotein and matrix protein, purified from the supernatant, were non-pyrogenic. Aggregated stellate clusters of surface glycoproteins separated on sucrose gradients were pyrogenic in half of numerous tests performed with different batches of material. Treatment of virus with ether resulted in complete loss of pyrogenicity. Liposomes made from extracted viral lipid were non-pyrogenic. In contrast, virosomes made from the viral lipid and the aggregated stellate clusters of surface glycoproteins were pyrogenic. Hence, optimum pyrogenicity depends upon the integrity of the virus particle, but haemagglutinin and/or neuraminidase appear essential, and lipid may be involved.
Animals↗
Observations on the production of pyrogenic substances by rabbit and human leucocytes.
1. The mechanism of release of a pyrogen from leucocytes has been studied in cells obtained from sterile rabbit peritoneal exudates and from rabbit blood. Attempts were made to induce human leucocytes-from blood-to release a pyrogen. 2. Rabbit leucocytes, kept below 4 degrees C., were not pyrogenic and did not release any pyrogen when disintegrated. Incubating such cells, in various media, at 37 degrees C. led to the formation of a pyrogen which was heat-labile. The maximum yield was attained after 1(1/2) hours' incubation. 3. The formation of rabbit leucocytic pyrogen was prevented by freezing and thawing the leucocytes, by heating them to 56 degrees C. for half an hour before incubation, and by ageing them in the cold. 4. Nitrofurazone (5-nitro-2-furaldehyde semicarbazone) prevents the formation of leucocytic pyrogen when given by mouth to the cell-donor animals, or when added to leucocytes in intro. 5. Leucocytes from rabbit blood formed leucocytic pyrogen, on incubation in saline, and this formation was also inhibited by nitrofurazone. 6. No leucocytic pyrogen was released from human leucocytes subjected to mechanical, osmotic, or thermal damage, and it was not formed when the cells were incubated in saline. 7. The source of rabbit leucocytic pyrogen, the action of nitrofurazone on leucocytes, and the supposed role of leucocytic pyrogen in fever are discussed.
Animals↗
Pyrogenicity of human adenoviruses.
High doses (>1.56x10(7) p.f.u.) of purified preparations of human adenovirus types 3, 5 and 8 exhibited definite pyrogenic activity when injected intravenously into rabbits. Complete pyrogenic tolerance was obtained not only with homologous types but also with heterologous types of adenovirus. No pyrogenic cross-tolerance was observed between each of these three adenovirus types and paramyxovirus pyrogen or bacterial lipopolysaccharide. Adenovirus pyrogenicity was retained after UV-inactivation, whereas it was inactivated by heating at 56 degrees C for 30 min. Adenovirus pyrogenicity was not neutralized by mixing with homologous type-specific antiserum but non-pyrogenic doses (10(7) p.f.u.) of adenovirus types 3, 5 and 8 became highly pyrogenic in the presence of type-specific antibodies at the optimal virus:antibody ratio. This enhanced pyrogenicity depended upon the virus-antibody complex. From these results, it is probable that the pyrogenic activity of the virus-antibody complex, rather than the pyrogenic activity of the virions, is the main contributor to fever in adenovirus infection under actual physiological conditions.
Adenoviruses, Human↗
[Mechanisms for development of tolerance to repeated injections of exogenous pyrogens].
Pyrogenic tolerance has been recognized for many years in a variety of species although the mechanisms that are responsible for its development are not well understood. The development of pyrogenic tolerance is associated with the stepwise diminution of pathophysiological and behavioral responses induced by exogenous pyrogens, such as fever, reduction in food and water intake. Several studies either in vivo or ex vivo have indicated the role of various proinflammatory cytokines in the development of pyrogenic tolerance. Most of these studies have indicated that pyrogenic tolerance is associated with down-regulation of cytokine production as well as their biological activity. The mechanisms responsible for down-regulation of cytokine production during development of pyrogenic tolerance are unclear. Since glucocorticoids are required for induction of tolerance, it has been postulated that well known glucocorticoids-dependent negative feedback on the production and biological activity of cytokines may play an important role in development of pyrogenic tolerance. We can not, however, rule out possibility that other mechanisms may participate directly or indirectly in a suppression of cytokines response due to repeated exogenous pyrogen challenge. Either the enhanced uptake of exogenous pyrogens by the hepatic Kupffer cells or the desensitization to exogenous pyrogens by the loss of binding sites, have been proposed as an additional mechanisms which may participate in exogenous pyrogen hyporesponsiveness.
Animals↗
Studies on the pathogenesis of fever with influenzal viruses. III. The relation of tolerance to the production of endogenous pyrogen.
Tolerance to the pyrogenic action of intravenously injected virus has been studied in rabbits given either PR8 strain of influenza A virus or Newcastle disease virus (NDV). The following findings suggest that the capacity of the animal to release an endogenous pyrogen is a critical factor. (a) Viruses produce fever by the release of endogenous pyrogen. (b) Tolerance to the pyrogenic effect of reinjected virus is associated with a decrease or absence of endogenous pyrogen production. (c) Tolerance to virus fever may be induced by the prior injection of endogenous pyrogen. (d) Cross-tolerance has been demonstrated between virus and bacterial endotoxin (typhoid vaccine), both of which cause the release of endogenous pyrogen. A difference has been noted in the mechanism of tolerance to successive injections of virus and of bacterial endotoxin. Repeated injections of endotoxins bring about an accelerated clearance of these substances from the blood stream with the result that there is a diminished stimulus to endogenous pyrogen production. Tolerance to virus, on the other hand, is unaccompanied by changes in the rate at which virus disappears from the circulation. It is postulated that circulating endogenous pyrogen, induced by the injection of a number of pyrogenic agents including viruses, temporarily suppresses the further release of endogenous pyrogen and thereby contributes to virus tolerance.
Animals↗
International validation of novel pyrogen tests based on human monocytoid cells.
It is a requirement that parenteral medicines be tested for pyrogens (fever causing agents) using one of two animal-based tests: the rabbit pyrogen test and the bacterial endotoxin test. Understanding the human fever reaction has led to novel non-animal alternative tests based on in vitro activation of human monocytoid cells in response to pyrogens. Using 13 prototypic drugs, clean or contaminated with pyrogens, we have validated blindly six novel pyrogen tests in ten laboratories. Compared with the rabbit test, the new tests have a lower limit of detection and are more accurate as well as cost and time efficient. In contrast to the bacterial endotoxin test, all tests are able to detect Gram-positive pyrogens. The validation process showed that at least four of the tests meet quality criteria for pyrogen detection. These validated in vitro pyrogen tests overcome several shortcomings of animal-based pyrogen tests. Our data suggest that animal testing could be completely replaced by these evidence-based pyrogen tests and highlight their potential to further improve drug safety.
Animals↗
Studies on the pathogenesis of fever. IX. Characteristics of endogenous serum pyrogen and mechanisms governing its release.
The "endogenous serum pyrogen" that appears in the circulating blood after a single intravenous injection of endotoxin does not produce leukopenia in normal animals, fails to provoke the local Shwartzman reaction, and elicits no "tolerance" when injected daily. Suppression of the febrile response to endotoxin by prednisone does not prevent the appearance of pyrogen in the blood. Animals given large amounts of endotoxin daily continue to respond with high fevers despite failure of endogenous serum pyrogen to appear in detectable amounts after the first two or three injections. Analysis of the response to daily injections shows clearly that the fever during the first 2 hours after administration of endotoxin is unrelated to levels of endogenous serum pyrogen; in contrast, the magnitude of the fever after the 2nd hour correlates well with endogenous pyrogen in some instances. The leukopenic response to endotoxin could not be correlated with the appearance of endogenous serum pyrogen. The differences between endotoxin and endogenous pyrogen and the similarities between leukocyte extracts (sterile exudates) and endogenous pyrogen are summarized and discussed. Dissociation of the febrile response to bacterial endotoxin and levels of endogenous serum pyrogen are discussed and it is concluded that a mechanism involving both direct and indirect action of endotoxins offers the best explanation for the pyrogenic action of these bacterial products.
Animals↗
Studies on the pathogenesis of fever with influenzal viruses. I. The appearance of an endogenous pyrogen in the blood following intravenous injection of virus.
A substance with pyrogenic properties appears in the blood streams of rabbits made febrile by the intravenous inoculation of the PR8 strain of influenza A and Newcastle disease viruses (NDV). By means of a technique involving passive transfer of sera from animals given virus to recipient rabbits, the titer of circulating pyrogen was found to be closely correlated with the course of fever produced by virus. Certain properties of the pyrogen are described which differentiate it from the originally injected virus and suggest that the induced pyrogen is of endogenous origin. These properties resemble those of endogenous pyrogens occurring in other forms of experimental fever. The source of virus-induced pyrogen is unknown. In vitro incubation of virus with various constituents of the circulation did not result in the appearance of endogenous pyrogen. Granulocytopenia induced by HN(2) failed to influence either fever or the production of endogenous pyrogen in rabbits injected with NDV. Similarly, the intraperitoneal inoculation of NDV into prepared exudates did not modify the febrile response. These findings do not lend support to the possibility that the polymorphonuclear leukocyte is a significant source of endogenous pyrogen in virus-induced fever. It is concluded that the liberation of an endogenous pyrogen from some as yet undefined source is an essential step in the pathogenesis of fever caused by the influenza group of viruses.
Animals↗
Studies on the pathogenesis of fever. XIX. Localization of pyrogen in granulocytes.
Only intact exudate granulocytes from rabbits generated large amounts of endogenous pyrogen when incubated in 0.15 M NaCl. No matter how whole-cell lysates or combinations of subcellular fractions were incubated, their yields of pyrogen never approached those of whole cells; at most, only minimal amounts of pyrogen were formed, once the integrity of the cells had been destroyed. Some pyrogen could be extracted from disrupted cells, but never more than a fraction (<25%) of that released from incubated whole cells. The yield could be slightly improved by lowering the pH (to 3.5) and by increasing the volume of extraction fluid. Virtually all of the preformed pyrogen that could be extracted from sucroselysed cells was found in their cytoplasmic fraction. Contrary to the results of Herion et al. (3), none could be detected in the granular (or lysosomal) fraction. Likewise, all efforts to recover pyrogen from the membrane-nuclear fraction were unsuccessful. In keeping with the finding that preformed pyrogen is contained in the cytoplasmic fraction were the observations that practically all of the aldolase, a cytoplasmic enzyme, and very little of the acid phosphatase, a granular enzyme, were lost from the cells during the release of pyrogen. Lysozyme, an enzyme stored in both the granules and the cytoplasm, was partially released from the cells under the same circumstances. Neither the release of pyrogen nor its slight intracellular buildup that precedes release (4) were affected by concentrations of puromycin that block protein synthesis in the cells and prevent their activation. Hence, it is concluded that the release process, which also involves the formation of active pyrogen (4), does not require protein synthesis, whereas activation of the cells, which may involve the synthesis of an inactive precursor (2), does.
Acid Phosphatase↗
Studies on the origin of human leukocytic pyrogen.
Release of the protein molecule, leukocytic pyrogen, is one of the many reactions exhibited by leukocytes after phagocytosis. After the ingestion of heat-killed S. albus, a 3-4 hr latent period exists, during which human peripheral leukocytes release no pyrogen, yet cellular metabolism is altered in such a way that pyrogen output may subsequently occur in the absence of further phagocytosis. Transcription of messenger RNA and translation of new protein are initial events in the. activation process, since addition of the inhibitors, actinomycin D, and cycloheximide or puromycin, during this period markedly depressed or abolished subsequent pyrogen release. These effects were noted to be dependent upon the time of addition of the inhibitors. None of the inhibitor drugs interfered with cell viability as measured by phagocytosis and hexose monophosphate shunt activity, nor did they alter the pyrogenicity of preformed leukocytic pyrogen. Vincristine did not inhibit pyrogen formation, consistent with its reported failure to alter RNA synthesis in mature human granulocytes. The glycolytic inhibitor, sodium fluoride, blocked pyrogen release both when added prior to particle ingestion or 1 hr after the initiation of phagocytosis. Whereas inhibition of phagocytosis would explain the sodium fluoride effect prior to 1 hr, this was not observed in leukocyte preparations incubated for 1 hr with S. albus before adding sodium fluoride. When sodium fluoride was added to preparations 2 hr after the start of incubation, the LP production was unimpaired. Potassium cyanide had no effect on cell activation or pyrogen release. These findings suggest that the primary energy supply for the activation process is derived from high energy phosphate bonds provided by anaerobic glycolysis. Since the major amount of cell activation appears to occur in the 1st hr after phagocytosis, this energy might be involved in the induction of a genome leading to the transcription of m-RNA and its translation into new protein or is required for polysome integrity during protein synthesis. It is suggested that this new protein may be leukocytic pyrogen itself, or an enzyme responsible for cleaving it from an inactive precursor.
Animals↗
Role of surface glycoproteins in influenza virus pyrogenicity.
Eleven H3N2, seven H1N1 and three H3N1 influenza virus reassortants of the pyrogenic A/Puerto Rico/8/34-A/England/939/69 clone 7a (H3N2) (A/7A) and poorly pyrogenic A/Fiji/15899/83 (H1N1) (A/Fiji) parents were analysed genetically for the parental origin of their genes and for their pyrogenicity in ferrets. All H3N2 reassortants were pyrogenic and produced significantly more fever than A/Fiji but differences in pyrogenicity between them could not be correlated with either single or constellations of genes. All H1N1 reassortants were poorly pyrogenic compared with A/7A but one (Am29) produced significantly more fever than A/Fiji. No correlation of the increased fever with inserted A/7A genes was evident in Am29 and, while mutations were detected in the H1 haemagglutinin of this reassortant using monoclonal antibodies, similar mutations were present in the other H1N1 reassortants which showed no increase in fever production. The three H3N1 reassortants were intermediate in their pyrogenicity, being more pyrogenic than A/Fiji and less pyrogenic than A/7A. Overall, these results support previous conclusions that the haemagglutinin and/or neuraminidase play a major role in the pyrogenicity of influenza virus.
Animals↗
Rabbit macrophages secrete two biochemically and immunologically distinct endogenous pyrogens.
Rabbit endogenous pyrogens occurred in two forms. One was an apparently single protein with a pI of 7.3; the other was a family of proteins with pI values of 4.5 to 5.0. We selected two of the latter, with pI values of 4.6 and 4.72, as representative of the group and compared them with the pI 7.3 pyrogen. Antisera raised in three goats completely neutralized the pyrogenic activity of the pI 7.3 pyrogen. Larger doses of these antisera did not block the pyrogenic activity of either of the pI 4.5 to 5.0 pyrogens. The pI 7.3 pyrogen contained a free --SH group which was essential to its biological activity. It was inactivated by 100 mM N-ethylmaleimide or 200 mM iodoacetamide, bound to Thiol-Sepharose columns, and could be eluted from them with mercaptoethanol. Neither of the pI 4.5 to 5.0 pyrogens was inactivated by N-ethylmaleimide or iodoacetamide, and neither bound to Thiol-Sepharose. Both endogenous pyrogens gave negative results in the Limulus lysate test for bacterial endotoxins. These results suggest that the pI 7.3 and pI 4.5 to 5.0 endogenous pyrogens are not closely related to each other and are consistent with the idea that they may not be related at all. Alternative hypotheses are discussed.
Animals↗
Heterogeneity of rabbit endogenous pyrogens is not attributable to glycosylated variants of a single polypeptide chain.
Rabbit endogenous pyrogens were of about the same molecular size, but showed considerable heterogeneity of their isoelectric points. We attempted to show that this heterogeneity was attributable to variable glycosylation of a single polypeptide chain. When peritoneal exudate cells were stimulated to make pyrogens in the presence of 2-deoxy-D-glucose, there was a relatively trivial suppression of pyrogen release, and analysis by isoelectric focusing showed parallel inhibition of secretion of all the forms of endogenous pyrogen. When cells were stimulated in the presence of 3H-labeled amino acids and 14C-labeled glucosamine or glucose, the purified pyrogens were labeled with 3H but not with 14C. Macrophage membrane preparations were made which contained glycosyl transferases and could transfer sugar residues from sugar nucleotides to deglycosylated fetuin. These macrophage membrane preparations did not transfer sugars to the pI 7.3 endogenous pyrogen. Treatment of endogenous pyrogens with neuraminidase or with periodate produced no evidence suggesting that the pyrogens were glycosylated. Last, endogenous pyrogens did not bind to any of four lectins with different carbohydrate specificities. This evidence suggests that the heterogeneity of rabbit endogenous pyrogens is not attributable to glycosylation and must have some other cause.
Animals↗
Effect of ibuprofen on fever and metabolic changes induced by continuous infusion of leukocytic pyrogen (interleukin 1) or endotoxin.
Many of the metabolic sequelae to infection and inflammation, such as fever, trace mineral redistribution, skeletal muscle catabolism, and the acute-phase protein response, are mediated by leukocytic pyrogen (interleukin 1). In the anterior hypothalamus and in skeletal muscles leukocytic pyrogen appears to induce the synthesis of prostaglandin E2 which mediates fever and skeletal protein catabolism. It is unclear whether any additional metabolic responses to leukocytic pyrogen result from prostaglandin production. This study was undertaken to investigate the ability of ibuprofen, a specific cyclooxygenase inhibitor, to alter protein and trace metal responses to leukocytic pyrogen or endotoxin when given in quantities sufficient to block the febrile response. In guinea pigs given continuous infusions of leukocytic pyrogen or endotoxin, a 0.6 to 0.8 degrees C fever was observed within 4 h, and zinc and iron concentrations in serum fell by 63 to 78% (P less than 0.01). Rates of whole body amino acid appearance, oxidation, and incorporation into protein were all significantly increased by leukocytic pyrogen and endotoxin treatment, (P less than 0.05) as were the fractional hepatic and seromucoid protein synthesis rates in leukocytic pyrogen-treated animals (P less than 0.01). Muscle protein synthesis was unchanged. Although pretreatment with infusions of ibuprofen completely ablated the febrile response to leukocytic pyrogen and endotoxin, decreases in zinc and iron concentrations in serum and leukocytosis were unaffected. Overall increases in whole body amino acid kinetics induced by leukocytic pyrogen or endotoxin were only minimally affected by ibuprofen. We concluded that treatment with prostaglandin synthesis inhibitor ibuprofen did not affect whole body trace metal, hematological, or hepatic acute-phase-induced responses to leukocytic pyrogen or endotoxin, either because these responses are prostanoid independent or because they are only partially mediated by eicosanoid products.
Animals↗
Comparison of temperature rise interpretations between European and United States Pharmacopeias' pyrogen tests.
The European Pharmacopeia (EP) and the United States Pharmacopeia (USP) pyrogen test for parenterals involve the measurement of the temperature rise in rabbits following the intravenous injection of the test solution. Between the two methods, the conditions for the result "pyrogen free" or "pyrogen", as well as the number of rabbits tested, differ substantially. Therefore, both methods were compared with respect to the differences in temperature rise interpretations with special attention to the selectivity of the tests. To exclusively study the temperature rise interpretations, the temperature measurements were simulated with models. With an increasing mean temperature rise, an intermediate range exists where the probability of "pyrogen free" and of "pyrogen" cannot be ignored. A single pyrogen test still gives an unambiguous result, but in this range, the probability is rather high that additional tests will not reproduce the same result. This range is approximately 0.3 degrees C wide for the USP test and 0.2 degrees C wide for the EP test. Simulating the temperature rise with a normally distributed model, the intermediate range is narrower for the interpretation according to the EP than the USP. For a USP test, the probability of the test result "pyrogen free" decreases as lower mean temperature rises. However, the two methods are similar in the high probability range for the presence of pyrogens. At the edge of the intermediate range, a slight mean temperature rise of 0.05 degrees C significantly changes the probability of a pyrogen result. Within a rather wide mean temperature rise range (approximately 0.15 degrees C wide), a product will reliably fulfil the EP requirements but not the USP requirements. These main statements are rather robust and do not depend significantly on the model used. Different temperature rise distributions only result in negligible variations in the interpretation of the tests. Information more detailed than mean temperature rise and standard deviation of the temperature rises is not absolutely necessary. For product quality, it is much more useful to review and interpret all individual temperature rises measured than to interpret the results of the pyrogen test only [corrected].
Animals↗
Assay of pyrogenic contamination in pharmaceuticals by cytokine release from monocytes.
In 1984 it was reported that a batch of human recombinant growth hormone which had passed the rabbit pyrogen test and a Limulus amoebocyte lysate (LAL) test was pyrogenic in man (1). Further, it was shown that the growth hormone caused human monocytes to release leukocyte pyrogen which evoked fevers in rabbits (1). Leukocyte pyrogen is believed to comprise of a mixture of (at least) 2 lymphokines with potent pyrogenic and inflammatory activities, interleukin-1 (IL-1) and Tumour Necrosis Factor (TNF), which are synthesized and released by activated peripheral blood monocytes. The development at NIBSC of sensitive and specific bioassays and immunoassays of IL-1 (2) and TNF (3) have permitted a new type of pyrogen test based on the in vitro release by human monocytes of the lymphokines IL-1 and TNF. Studies are underway to evaluate the suitability of monocytic cell lines, rather than human monocytes, since these require a time-consuming and labour intensive preparation. Investigations are in progress to evaluate the suitability of the above "monocyte test" for pyrogen to replace or complement the rabbit pyrogen test which is routinely applied to biological medicines. The new method has already proved useful in detecting pyrogenic contamination of a large volume parenteral medicinal product which passed the rabbit pyrogen test but caused adverse reactions in patients.
Cells, Cultured↗