Course of fever response to repeated administration of sublethal doses of lipopolysaccharides,polyinosinic: Polycytidylic acid and muramyl dipeptide to rabbits

Summary The purpose of the present study was to examine the development of tolerance to three structurally dissimilar pyrogens, i.e., lipopolysaccharide (LPS), muramyl dipeptide (MDP) and polyinosinic: polycytidylic acid (poly I:C) in rabbits. The possibility of pyrogenic cross-tolerance among these agents has also been studied. It was observed that repeated injection of sublethal doses of LPS and MDP was connected with the changing of biphasic fever to monophasic. The consequence of this was a drop in the fever index. In contrast to LPS and MDP, the repeated administration of poly I:C did not result in such changes. Successive injections of this pyrogen always evoked biphasic fever. We also demonstrated that pyrogenic cross-tolerance between LPS and MDP did not occur. The cross-tolerance between LPS and MDP did not occur. The cross-tolerance among pyrogens was possible if they originated from the same class, for example endotoxin fromSalmonella abortus eq. and endotoxin fromEscherichia coli.     

Lack of pyrogenic tolerance transmission between brain and periphery in the rabbit

Summary Successive injections of lipopolysaccharide (LPS) either intravenously (i.v.) or intracerebroventricularly (i.c.v.) induced pyrogenic tolerance to LPS in rabbits. Tolerance was shown by a decrease of the magnitude of the fever response to repeated doses of LPS, irrespective of the route of pyrogen administration. A significantly greater and more dramatic decrease of the fever index, however, was observed in rabbits made tolerant to pyrogen given i.v. than when the pyrogen was given i.c.v. Transmission of the pyrogenic toleraance between brain and peripheral tissues, however, has not been ascertained.     

Lack of pyrogenic tolerance transmission between brain and periphery in the rabbit

Successive injections of lipopolysaccharide (LPS) either intravenously (i.v.) or intracerebroventricularly (i.c.v.) induced pyrogenic tolerance to LPS in rabbits. Tolerance was shown by a decrease of the magnitude of the fever response to repeated doses of LPS, irrespective of the route of pyrogen administration. A significantly greater and more dramatic decrease of the fever index, however, was observed in rabbits made tolerant to pyrogen given i.v. than when the pyrogen was given i.c.v. Transmission of the pyrogenic tolerance between brain and peripheral tissues, however, has not been ascertained.     

Depletion of hypothalamic norepinephrine reduces the fever induced by polyriboinosinic acid: polyribocytidylic acid (Poly I:Poly C) in rats

Administration of either Poly I:Poly C (0.05-0.50 micrograms) or norepinephrine (2-8 micrograms) into the anterior hypothalamic area produced a dose-related fever in rats. The fever induced by Poly I:Poly C was attenuated after selective depletion of norepinephrine in the hypothalamus. However, selective depletion of hypothalamic norepinephrine did not affect the fever induced by intrahypothalamic norepinephrine. The data indicate that Poly I:Poly C may act to induce fever through the endogenous release of norepinephrine from the rat's hypothalamus.     

Endogenous pyrogen formation by human blood monocytes stimulated by polyriboinosinic acid:Polyribocytidylic acid

The pyrogenic response to supernatants from human blood monocytes stimulated with polyriboinosinic acid:polyribocytidylic acid (poly I:C) was characteristic of a response to endogenous pyrogen in that it was brief and monophasic, and was destroyed by heating the supernatants at 70°C for 30 min. Pyrogen production was unimpaired when the incubations were carried out in the presence of cycloheximide (50 g/ml; an inhibitor of protein synthesis) or indomethacin (50 g/ml; an inhibitor of prostaglandin synthesis). Also, neither interferon, interleukins, tumor necrosis factor nor prostaglandin E₂ were detectable in the supernatants from the poly I:C-stimulated human monocytes.     

Depletion of hypothalamic norepinephrine reduces the fever induced by polyriboinosinic acid: polyribocytidylic acid (Poly I:Poly C) in rats

Summary Administration of either Poly I:Poly C (0.05–0.50 g) or norepinephrine (2–8 g) into the anterior hypothalamic area produced a dose-related fever in rats. The fever induced by Poly I:Poly C was attenuated after selective depletion of norepinephrine in the hypothalamus. However, selective depletion of hypothalamic norepinephrine did not affect the fever induced by intrahypothalamic norepinephrine. The data indicate that Poly I:Poly C may act to induce fever through the endogenous release of norepinephrine from the rat's hypothalamus.This work was supported by grants from the National Science Council (Taipei, Republic of China).     

Effect of synthetic polynucleotides on the growth of transplantable tumours in BALB/c mice.

The effect of BALB/c mice pretreatment with tumour cells (a mammary adenocarcinoma, ADK-1t and an IgA secreting plasmocytoma, MOPC-315) adsorbed with poly I:C, poly I and poly C is examined. Only mice pretreated with cells of both tumours adsorbed with poly I:C and poly C proved to be extensively protected against challenge by homologous untreated tumour cells, whereas this was not so in the case of poly I. A possible explanation of this phenomenon is discussed.     

Effect of synthetic polynucleotides on the growth of transplantable tumours in BALB/c mice

Summary The effect of BALB/c mice pretreatment with tumour cells (a mammary adenocarcinoma, ADK-1t and an IgA secreting plasmocytoma, MOPC-315) adsorbed with poly I:C, poly I and poly C is examined. Only mice pretreated with cells of both tumours adsorbed with poly I:C and poly C proved to be extensively protected against challenge by homologous untreated tumour cells, whereas this was not so in the case of poly I. A possible explanation of this phenomenon is discussed.This work was supported by a research contract with the Italian National Research Council (C.N.R.).     

Absence of endotoxin-fever but not hyperthermia in Brattleboro rats

I.c.v. administration of bacterial endotoxin produced a fever in the Long-Evans rat but not in the Brattleboro rat. Similar administration of arachidonic acid, prostaglandin E2, prostacyclin, dibutyryl cAMP, norepinephrine, morphine and beta-endorphin caused hyperthermia in both Long-Evans and Brattleboro rats. Variable doses of exogenous arginine vasopressin (AVP) when centrally administered with endotoxin caused fever in the Brattleboro rat. It is suggested that AVP may play an important role in the production and release of endogenous pyrogen.     

Absence of endotoxin-fever but not hyperthermia in Brattleboro rats

Summary I. c. v. administration of bacterial endotoxin produced a fever in the Long-Evans rat but not in the Brattleboro rat. Similar administration of arachidonic acid, prostaglandin E₂, prostacyclin, dibutyryl cAMP, norepinephrine, morphine and -endorphin caused hyperthermia in both Long-Evans and Brattleboro rats. Variable doses of exogenous arginine vasopressin (AVP) when centrally administered with endotoxin caused fever in the Brattleboro rat. It is suggested that AVP may play an important role in the production and release of endogenous pyrogen.     

Colony stimulating activity in acute and chronic endotoxinemia in man

Summary Blood granulocyte-macrophage colony stimulating activity (GM CSF) was measured in 6 normal individuals challenged with low-dose endotoxin and in 63 unselected patients with nonhaematological disorders. 5/63 patients were febrile and 5 other patients showed detectable endotoxin levels, as measured by the Limulus assay. CSA levels showed a rapid increase in normal individuals following endotoxin administration, but were in the normal range in patients with chronic endotoxinemia or in those with febrile disorders. Thus, unlike acute endotoxinemia, chronic endotoxinemia is not associated with elevated activity that promotes growth of myeloid commited stem cells. In addition, fever per se did not coincide with elevated blood CSA levels.     

Colony stimulating activity in acute and chronic endotoxinemia in man.

Blood granulocyte-macrophage colony stimulating activity (GM CSF) was measured in 6 normal individuals challenged with low-dose endotoxin and in 63 unselected patients with nonhaematological disorders. 5/63 patients were febrile and 5 other patients whoed detectable endotoxin levels, as measured by the Limulus assay. CSA levels showed a rapid increase in normal individuals following endotoxin administration, but were in the normal range in patients with chronic endotoxinemia or in those with febrile disorders. Thus, unlike acute endotoxinemia, chronic endotoxinemia is not associated with elevated activity that promotes growth of myeloid commited stem cells. In addition, fever per se did not coincide with elevated blood CSA levels.     

Resistance of in vivo-selected spontaneously transformed cells and Rous sarcoma virus-transformed cells to macrophage-mediated cytotoxicity

The cytotoxic activity (CTA) of activated peritoneal macrophages (MP) on variant lines of Syrian hamster embryo (HE) cells of differing malignant characteristics was studied. The target cells were a line of low-malignant cells resulting from spontaneous transformation of HE cells in vitro (STHE strain), and malignant variants selected from them in vivo (STHE-LM-4, STHE-LM-8, and STHE-75/18 strains). In addition, we used cells of the HET-SR-1 strain; these are HE cells transformed in vitro by a tumorigenic Rous sarcoma virus (Schmidt-Ruppin strain, RSV-SR), or the TU-SR strain induced by RSV-SR in vivo. Thioglycollate-elicited peritoneal MP from Syrian hamsters were activated in vitro with bacterial levan, LPS or MDP and used as effector cells. MP-mediated cytolysis was determined by means of a 42-h radioactivity release assay with³H-thymidine-labeled target cells. We found that only the parental STHE cells were susceptible towards fully-activated MP-mediated CTA. All three of the in vivo-selected malignant variants of the STHE cell sublines, as well as the tumorigenic RSV-SR transformants, were resistant to cytolysis by activated MP. Non-activated thioglycollate-elicited MP did not lyse any of the tumor cells studied.     

Resistance of in vivo-selected spontaneously transformed cells and Rous sarcoma virus-transformed cells to macrophage-mediated cytotoxicity.

The cytotoxic activity (CTA) of activated peritoneal macrophages (MP) on variant lines of Syrian hamster embryo (HE) cells of differing malignant characteristics was studied. The target cells were a line of low-malignant cells resulting from spontaneous transformation of HE cells in vitro (STHE strain), and malignant variants selected from them in vivo (STHE-LM-4, STHE-LM-8, and STHE-75/18 strains). In addition, we used cells of the HET-SR-1 strain; these are HE cells transformed in vitro by a tumorigenic Rous sarcoma virus (Schmidt-Ruppin strain, RSV-SR), or the TU-SR strain induced by RSV-SR in vivo. Thioglycollate-elicited peritoneal MP from Syrian hamsters were activated in vitro with bacterial levan, LPS or MDP and used as effector cells. MP-mediated cytolysis was determined by means of a 42-h radioactivity release assay with 3H-thymidine-labeled target cells. We found that only the parental STHE cells were susceptible towards fully-activated MP-mediated CTA. All three of the in vivo-selected malignant variants of the STHE cell sublines, as well as the tumorigenic RSV-SR transformants, were resistant to cytolysis by activated MP. Non-activated thioglycollate-elicited MP did not lyse any of the tumor cells studied.     

Antibody to tumor necrosis factor (TNF) reduces endotoxin fever

Summary Antibody to tumor necrosis factor (TNF), injected intravenously, reduced endotoxin fever in the rabbit. The fever-reducing effect was apparent in the latter half of the febrile response.This work was supported by a Grants-in-Aid from the Ministry of Education, Science and Culture of Japan (Grant No. 62480112).     

Antibody to tumor necrosis factor (TNF) reduces endotoxin fever

Antibody to tumor necrosis factor (TNF), injected intravenously, reduced endotoxin fever in the rabbit. The fever-reducing effect was apparent in the latter half of the febrile response.     

Inhibited hormonal induction of hepatic phosphoenolpyruvate carboxykinase in poly I∶C treated mice,an endotoxin-like glucocorticoid antagonism

Summary Corticosteroid induction of mouse hepatic phosphoenolpyruvate carboxykinase was inhibited by prior injection of poly IC. Mice challenged with a lethal dose of endotoxin 4 h after administration of poly IC could not be protected by a concurrent injection of hydrocortisone.This investigation was supported by U. S. Public Health Service research grant No. AI-10087 from the National Institute of Allergy and Infectious Diseases.     

Lack of tolerance development to tumor necrosis factor α inside the central nervous system

Tumor necrosis factor (TNF) was repeatedly microinfused into the lateral ventricle of guinea pig brains at a dose of 200 ng, 4 times within 150 min, at intervals of 3 days. In comparison to guinea pigs infused with solvent according to the same time schedule, the animals responded to TNF with pronounced fevers. The quantity of the fever response was the same after each of the 4 microinfusions of TNF. Three days after the last infusion of TNF or solvent all animals received an intramuscular injection of bacterial lipopolysaccharide (LPS). The fever in response to LPS was the same in both groups. Thus, the reported development of tolerance to repeated systemic administration of TNF^1–3 does not develop inside the blood-brain barrier. Also, the febrile response to LPS is not influenced by repeated central pre-treatment with TNF, whereas repeated peripheral treatment does have an effect.     

Purfication and molecular weight of an RNA-dependant RNA polymerase from Brassicae oleracea var. Botrytis]

An RNA-dependent RNA polymerase has been completely purified from Cauliflower inflorescences. Analysis of the purified enzyme on SDS-polyacrylamide gels showed one polypeptide chain with a molecular weight of 140,000 dalton. The enzyme is monomeric in its native state. The in vitro activity was completely dependent on added RNA, the most efficient templates being poly (U), poly (U, C), poly (I) and viral RNA.     

Changes in body temperature and circulating levels of interleukin-6 after intra-arterial injections or infusions of tumor necrosis factor α in guinea pigs

Tumor necrosis factor (TNF) is released systematically during the early phase of endotoxin induced fever. To study the effects of this cytokine in guinea pigs, 2 g TNF were intra-arterially injected as a bolus or slowly infused within 60 min. Both modes of administration induced a biphasic elevation of the animals' abdominal temperature lasting 6 h and stimulated the release of endogenous interleukin-6 (IL-6)-like activity. The second phase of the thermal response and the release of endogenous IL-6-like activity were significantly higher, when TNF was slowly infused into the animals' circulation, in spite of a transiently higher TNF-like activity after the bolus injection of TNF. Both TNF and IL-6 may therefore be regarded as candidates to trigger the febrile response in guinea pigs.