Restoration of normal febrile response to endotoxin in pyrogen-tolerant rabbits by injection with human beta interferon.

Early-phase pyrogen tolerance was induced in rabbits by two consecutive daily injections of 125 ng of endotoxin per kg of body weight. The second injection of the same dose of endotoxin evoked only a monophasic fever with a peak response 1.5 h after the injection; no second peak was observed. The rabbits were released from the tolerance to develop a typical biphasic fever by an injection of 125 ng of endotoxin along with human beta interferon (HuIFN-beta), although the tolerance-inducing amount of endotoxin alone could not. The profile of the febrile response of tolerant rabbits injected with both endotoxin and HuIFN-beta could not be distinguished from that of normal rabbits. There was no essential difference between natural and recombinant HuIFN-beta in breaking tolerance. Heat-stable (70 degrees C, 30 min) endogenous pyrogen or tumor necrosis factor was increased significantly in concentration in the serum of tolerance-broken rabbits. These results suggest that HuIFN-beta stimulates the production of tumor necrosis factor in tolerant rabbits to elicit the second peak of febrile response.     

Mechanism of augmentation of endotoxin fever by beta interferon in rabbits: possible participation of tumor necrosis factor (cachectin).

We analyzed the mechanism of the augmentation of endotoxin fever by human beta interferon (IFN) cross-reacting to rabbit cells in rabbits by using a purified rabbit tumor necrosis factor (RaTNF) and a monoclonal anti-RaTNF. The late peak of fever evoked by the injection with both endotoxin and HuIFN was suppressed when the animals were injected previously with anti-RaTNF. IFN also augmented the pyrogenicity of RaTNF in a synergistic manner in rabbits. The blood collected 2 h after the injection of RaTNF plus IFN contained a significant endogenous TNF activity, and the serum was shown to be pyrogenic. The endogenous pyrogen activity in the 2-h blood was heat stable (70 degrees C, 30 min) and was reduced by the in vitro treatment with anti-RaTNF. These results suggest that IFN augments the febrile response of rabbits to endotoxin by stimulating endogenous TNF-mediated TNF production to induce the late peak of fever.     

Provocation of pulmonary vascular endothelial injury in rabbits by human recombinant interleukin-1 beta.

Interleukin-1 (IL-1) mediates components of the acute-phase response, stimulates granulocyte metabolism, and induces endothelial cell surface changes. We studied the effects of human recombinant IL-1 beta (rIL-1 beta) or rIL-1 alpha on circulating granulocytes, their sequestration within the pulmonary microvasculature, pulmonary edema formation, and changes in pulmonary vascular permeability to 125I-labeled albumin. rIL-1 beta administration induced significant (P less than 0.03) but transient granulocytopenia followed by significant (P less than 0.04) neutrophilia and significant (P less than 0.04) pulmonary leukostasis compared with saline-infused rabbits. Rabbits preinfused with 125I-labeled rabbit serum albumin and administered saline, rIL-1 beta, or rIL-1 alpha were sacrificed, and lung wet/dry weight ratios and bronchoalveolar lavage fluid and plasma 125I activities determined. Both rIL-1 beta and rIL-1 alpha increased lung wet/dry weight ratios (P less than 0.025 and P less than 0.01, respectively) compared with saline controls. rIL-1 beta increased bronchoalveolar lavage fluid/plasma 125I radioactivity ratios (P less than 0.025). Electron microscopic analysis of lung sections obtained from rIL-1 beta-infused animals demonstrated endothelial injury, perivascular edema, and extravasation of an ultrastructural permeability tracer. The observation that human rIL-1 can evoke acute pulmonary vascular endothelial injury and lung edema in rabbits supports the hypothesis that IL-1 may play a role in the pathogenesis of the adult respiratory distress syndrome.     

Induction of tubuloreticular structures in cultured human endothelial cells by recombinant interferon alfa and beta.

Tubuloreticular structures were induced in human umbilical vein endothelial cells cultured in media containing recombinant interferon alfa and beta but not in media containing recombinant interferon gamma or other agents that induce interferon, such as 5-bromodeoxyuridine or polyinosinicpolycytidylic acid. Recombinant interferon beta induced tubuloreticular structures in endothelial cells at a lower concentration and in a greater percentage of cell sections than recombinant interferon alfa. This report of tubuloreticular structures being induced in vitro in nonlymphoid cells provides evidence that interferon is the substance that causes the formation of tubuloreticular structures in endothelial cells in vivo.     

Augmentation of human polymorphonuclear leukocyte adherence by interferon

Augmentation of human polymorphonuclear leucocyte adherence by alpha and gamma interferons occurred as early as 2 min after incubation. Enhancement of adherence occurred at optimal concentrations of 100-1,000 IU/ml. There was synergism between alpha and gamma interferons, but not between two subtypes of alpha interferon, on augmentation of adherence, indicating that alpha and gamma interferons act on different receptors on the polymorphonuclear leucocyte. Heat treatment at 65 degrees C for 30 min abolished the effect of interferon on adherence.     

Antibacterial activity of recombinant murine beta interferon.

Recombinant murine beta interferon was protective and therapeutic for mice against Listeria monocytogenes infection in vivo. The recombinant murine beta interferon caused enhanced H2O2 release by macrophages in vivo, but not in vitro.     

Radioimmunoassay for human beta interferon.

Pure human beta interferon (Hu IFN-beta) (formerly human fibroblast interferon) was used to raise antibodies in rabbits. Anti-IFN-beta immunoglobulins from rabbit serum were purified by IFN-beta affinity chromatography and were used in the development of a sandwich-type radioimmunoassay for Hu IFN-beta. This radioimmunoassay consisted of (i) incubating Hu IFN-beta with anti-IFN-beta immunoglobulins immobilized on Sepharose 4B beads and (ii) incubating the resulting solid-phase IFN antibody complex with 125I-labeled anti-Hu IFN-beta immunoglobulins. The amount of 125I-labeled anti-Hu IFN-beta bound to the complex was linearly proportional to the amount of antiviral activity present in the complex from 0 to 500 U of standard IFN-beta per ml; 1 U of antiviral activity was equivalent to about 40 cpm of 125I-labeled anti-IFN immunoglobulins in the radioimmunoassay. The results of the radioimmunoassay were not influenced by the protein content of the IFN sample assayed, and the degree of intraassay variability was low; coefficients of variability were 9.4% at 5 U/ml and 1.1% at 500 U/ml. Thus, compared with the traditional antiviral assay for IFN, this radioimmunoassay was equally sensitive and more precise. In addition, it was highly specific for Hu IFN-beta and took only 5 h to complete.     

二甲亚砜对家兔内毒素性发热的影响

目的:观察二甲亚砜(DMSO)对家兔内毒素性发热的影响。方法:以健康封闭群新西兰兔为实验对象,随机分组。经耳缘静脉注射内毒素(ET)和DMSO,用WRY-B型微机热原测温仪测定家兔的结肠温度。结果:静脉注射ET引起家兔结肠温度双相性升高,其发热反应指数明显高于对照组。静脉注射ET10min前注射不同剂量DMSO组,家兔发热反应指数明显低于静脉注射内毒素组,并呈剂量依赖关系。静脉注射ET(0.4μg/mL,1mL/kg)10min后注射DMSO(60%,1mL/kg)组,发热反应指数同样明显低于静脉注射内毒素组。结论:DMSO明显抑制家兔内毒素性发热。     

Potentiation of lymphocyte natural killing by mixtures of alpha or beta interferon with recombinant gamma interferon.

Human lymphocytes were treated with human alpha (IFN-alpha), beta (IFN-beta), or recombinant gamma (IFN-gamma) interferons separately or in combination to determine their ability to enhance natural killing against mouse L cell targets. Our results showed that recombinant IFN-gamma was approximately 50 times more active per unit of antiviral activity than either IFN-alpha or IFN-beta. Moreover, the levels of natural killing by lymphocytes treated with combinations of IFN-alpha and IFN-beta were additive, whereas combinations of recombinant IFN-gamma and IFN-alpha or recombinant IFN-gamma and IFN-beta were synergistic. The development of natural killing in lymphocytes treated with recombinant IFN-gamma did not occur more rapidly but reached higher levels (62%) than that observed with lymphocytes treated with IFN-alpha or IFN-beta (15%). The results suggest the importance of IFN-gamma and mixtures of IFN-gamma with IFN-alpha or IFN-beta in the enhancement of natural killing activity against virus infections and neoplasia.     

Reduction in antiviral activity of human beta interferon by gallic acid.

Gallic acid (GA) is a common part of the human diet, both in the free form and as a metabolite of tannic acid and propyl gallate. Cell cultures were incubated with mixtures of either GA and beta interferon (IFN-beta) (formerly fibroblast IFN) or medium and IFN-beta. The cells were subsequently challenged with virus. The virus plaque yields were greater in cells incubated with IFN-beta and GA than in cells incubated with IFN-beta and medium, indicating that in the former mixture, IFN-beta had lost antiviral activity. The magnitude of the loss was dependent upon the GA concentration. IFN-alpha and IFN-gamma (formerly leukocyte IFN and immune IFN, respectively) were not similarly affected. The effect of GA on IFN-beta could be reversed with 2-mercaptoethanol, suggesting a possible sulfhydryl involvement. Extensive dialysis of IFN-beta-GA mixtures to remove the GA failed to reverse the reduction in antiviral activity. This suggests that a direct and irreversible interaction between IFN-beta and GA took place, reducing the activity of IFN-beta. The significance of this finding with regard to virus infections of the intestine is discussed.     

Augmentation of host resistance to microbial infections by recombinant human interleukin-1 alpha.

Recombinant human interleukin-1 alpha augmented resistance of mice to microbial infections caused by Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus pneumoniae, Salmonella typhimurium, and Candida albicans. The effective doses of interleukin-1 alpha ranged from 0.01 to 10 micrograms per mouse, depending on the infecting organism, route of administration, and challenge dose. Intravenous interleukin-1 alpha was, dose for dose, more effective than intravenous muramyl dipeptide and lentinan against the P. aeruginosa and K. pneumoniae infections. Augmentation by interleukin-1 alpha of resistance to infection was also observed in P. aeruginosa-infected mice in a state of cyclophosphamide-induced leucopenia. Interleukin-1 alpha may be useful for controlling obstinate infections not curable by antimicrobial agents alone.     

Augmentation of natural and antibody-dependent cell-mediated cytotoxicity by pure human leukocyte interferon

Augmentation of the cytolytic activity of human natural killer cells and of antibody-dependent cell-mediated cytotoxicity has been attributed to human interferons. With the purification to homogeneity of human leukocyte interferon, it became possible to test directly whether pure interferon could increase the activity of these effector cells. Treatment of purified blood mononuclear cells with pure interferon resulted in substantial increases in natural killer cell activity and in antibody-dependent cell-mediated cytotoxicity. Concentrations of 10–100 units/ml of antiviral activity were sufficient to augment appreciably natural killer cell activity.     

Spontaneous production of gamma interferon and induced production of beta interferon by human T-lymphoblastoid cell lines.

Two human T-lymphoblastoid cell lines, CCRF/CEM and Molt 4, produced beta interferon (IFN-beta) upon infection with Sendai virus. Molt 4, but not CCRF/CEM, spontaneously produced up to 300 U of IFN-gamma per ml, apparently not contaminated with IFN-alpha or -beta. Phytohemagglutinin, a T-cell mitogen, did not stimulate IFN production in these lines. A third T-lymphoblastoid line, CCRF/HSB2, produced no IFN either spontaneously or after infection with Sendai virus or treatment with phytohemagglutinin. The Molt 4 cells contained an mRNA which could be translated by oocytes to give IFN-gamma. Molt 4 cells therefore provide a convenient source of human IFN-gamma and its mRNA for experimental purposes.     

Pharmacokinetic properties of human fibroblast and leukocyte interferon in rabbits.

When rabbits were given intramuscular injections of the same quantities of human leukocyte or fibroblast interferons, the former produced moderately higher levels of circulating interferon. Fibroblast interferon was not cleared faster from circulation, nor was direct inactivation by rabbit blood responsible for this difference.     

家兔内毒素热限和前列腺素E热限成因的比较研究

本研究用114只新西兰白兔进行三部分实验。1.家兔静脉注射非热限剂量、热限剂量ET引起发热时,PGE_2含量变化与体温变化之间无明显正相关(p>0.05),即ET性发热达到热限时,PGE_2含量增多不受限。2.侧脑室注射不同剂量PGEt引起的发热呈剂量一效应依赖关系,但当PGE_2剂量递增达到一定水平后,再增加剂量,发热效应不再随之增强,出现“PGE热限”。3.非热限剂量、热限剂量PGE_2引起发热时,脑脊液中cAMP含量变化与体温变化之间呈明显正相关(r=0.9906,p<0.01),PGE_2性发热达到热限水平后,cAMP含量的增多受限。作者推论:PGE可能不参与ET热限的构成,在ET性发热机制中,PGE可能不是主要的中枢介质:PGE作为致热物质也有热限存在。cAMP可能是构成PGE热限的重要介质。     

Augmentation of natural killer cytotoxicity by alpha or gamma natural and recombinant interferons and interferon inducers. Effect of monocytes

We investigated the effect of human peripheral blood monocytes on the augmentation of natural killer cytotoxicity by alpha or gamma natural and recombinant interferons (IFN) and certain interferon inducers. We observed that: (1) in the majority of the donors examined (75%) human peripheral blood monocytes do not affect natural killer cytotoxicity, determined by a 4-hour chromium-51 release assay, against target cells from hemopoietic human tumor cell lines. (2) Monocytes are not required and do not affect the augmentation of natural killer cytotoxicity by Escherichia coli-derived IFN-gamma, natural human IFN-gamma, E. Coli-derived IFN-alpha 2 or natural human IFN-alpha. E. Coli-derived IFN-gamma and natural human IFN-gamma have been reported to activate monocyte cytotoxicity determined in 72-hour assay. (3) Monocytes are not required for the augmentation of natural killer cytotoxicity against target cells from hemopoietic tumor cell lines by polyinosinic acid-polycytidylic acid or staphylococcal enterotoxin A.     

The enhancement of interferon production by endotoxin

Summary Pretreatment of bovine leukocyte cultures with endotoxin enhanced interferon production by Newcastle disease virus (NDV) as evidenced by an early and high rate of interferon production. This enhancing effect was greatest when NDV was inoculated at three hours after endotoxin treatment. It was blocked by actinomycin D both before and after the addition of endotoxin. Propagation of NDV was less marked in endotoxin-treated cultures than in untreated control cultures. Pretreatment with endotoxin interfered with the cytopathic effect of the NDV on the cultured cells.     

Inhibition of growth of Toxoplasma gondii in cultured fibroblasts by human recombinant gamma interferon.

The growth of Toxoplasma gondii in cultured human fibroblasts was inhibited by recombinant human gamma interferon at concentrations of 8 to 16 U/ml. The interferon was titrated by observing a total inhibition of parasite plaque formation 7 days after infection. Inhibition of the growth of T. gondii in the early days after infection was measured by marked reductions in the incorporation of radioactive uracil, a precursor that can only be used by the parasites. This assay showed that when cells were pretreated with gamma interferon for 1 day and then infected, inhibition of T. gondii growth could be readily detected 1 or 2 days after infection. When the pretreatment was omitted and parasites and gamma interferon were added at the same time, no inhibition of parasite growth could be detected 1 day later, although it was apparent after 2 days. Cultures from which the gamma interferon had been removed by washing after a 1-day treatment showed inhibition of T. gondii growth. Gamma interferon had no effect on the viability of extracellular parasites, but it did inhibit the synthesis of host cell RNA and protein by ca. 50% 3 days after treatment. This degree of inhibition is unlikely, of itself, to compromise the growth of T. gondii. Recombinant alpha and beta interferons had no effect on the growth of T. gondii.