Differential efficacies of human type I and type II interferons as antiviral and antiproliferative agents

Designing monomeric IFNγ: The significance of domain-swapped dimer structure in IFNγ immune responses

Interferon (IFN) γ can initiate immune responses by inducing the expression of major histocompatibility complex molecules, suggesting its potential for cancer immunotherapy. However, it also has an immunosuppressive function that limits its application as a therapeutic agent. IFNγ has a characteristic domain-swapped dimer structure with two of the six α-helices exchanged with each other. As we hypothesized that the contrasting functions of IFNγ could be attributed to its unique domain-swapped structure, we designed monomeric IFNγ by transforming the domain-swapped dimer structure of WT IFNγ. We conjectured the evolution of this domain-swapped dimer and hypothesized that the current IFNγ structure emerged through shortening of the loop structure at the base of the swapped domain and the accumulation of hydrophobic amino acids at the newly generated interface during domain-swapping. We then designed and generated a stable monomeric IFNγ by retracing this evolutionary process, complementing the lost loop structure with a linker, and replacing the accumulated hydrophobic amino acids with hydrophilic ones. We determined that the designed variant was a monomer based on molecular size and number of epitopes and exhibited activity in cell-based assays. Notably, the monomeric IFNγ showed a qualitatively similar balance between immunostimulatory and immunosuppressive gene expression as WT IFNγ. This study demonstrates that the structural format of IFNγ affects the strength of its activity rather than regulating the fate of downstream gene expression.

Normal and keloid fibroblasts are differentially influenced by IFN-γ and triamcinolone as well as by their combination

Impaired wound healing as well as imbalanced cell proliferation and extracellular matrix synthesis and degeneration can cause aberrant scarring. The most severe impacts of such scarring on patients' lives are stigmatization and physical restriction. Although, a broad variety of combinatorial approaches with, e.g., glucocorticoids, chemotherapeutics, and immunomodulators are used, there is still a high recurrence rate of keloids. The aim of this study was to investigate which influence interferon γ (IFN-γ, 1.000-10.000 IU/mL) and/or triamcinolone acetonide (TA, 1 μg/mL) have on proliferation, cell viability, collagen type I synthesis, and cytokine secretion in healthy and keloid fibroblasts. It was shown that mono-treatment with IFN-γ or TA for 2 days induced a severe reduction of the proliferative potential in both cell species. The combinatory treatment (IFN-γ plus TA) of keloid fibroblasts enhanced the anti-proliferative effect of the mono-treatments, whereas no additional anti-proliferative effect was observed in normal fibroblasts. Furthermore, we observed that the combinatory treatment regimen reduced the expression of α-smooth muscle actin (α-SMA), an actin isotype contributing to cell-generated mechanical tension, in keloid fibroblasts. In normal fibroblasts, α-SMA was reduced by the mono-treatment with IFN-γ as well as by the combinatory treatment. The analysis of collagen-type I synthesis revealed that TA did not reduce collagen type I synthesis in normal fibroblasts but in keloid fibroblasts. IFN-γ reduced in both cell species the collagen type I synthesis. The combination of TA and IFN-γ intensified the previously observed collagen type I synthesis reduction in keloid fibroblasts. The herein presented data suggest the combinatory application of IFN-γ and TA as a promising therapy concept for keloids.

A phase I trial of recombinant gamma interferon administered intravenously on a daily × 5 schedule

Objective: To determine the maximally tolerated dose and associated toxicity of r-γ-IFN. In addition, to evaluate the development of serum IFN neutralizing factors. Design: This is an open-labeled, Phase I dose escalating trial.

Setting: This trial was carried out at a Veteran's Administration and Army hospital.

Patients: Patients with advanced malignancies for whom no known effective therapy is available were eligible. Patients must have adequate organ function, a performance status of 2 or lower and a minimal life expectancy of 2 months.

Intervention: Patients received escalating doses of r-γ-IFN (0.5, 1.0, 2.0, 4.0, 6.0, 8.0, 10.0 X 106 IU/m2) daily for 5 days given intravenously over 2 hours every other week.

Main Outcome Measures: Tumor response was followed clinically, with radiographic support when appropriate. Toxicity was evaluated using the World Health Organization (WHO) standard toxicity grading guidelines. Serum samples were used to monitor and evaluate the IFN neutralizing factors.

Promotion of expression of interferon-stimulated genes in U937 monocytic cells by HIV RNAs, measured using stable isotope labeling with amino acids in cell culture (SILAC)

Type I interferon (IFN) exerts strong antiviral activity, particularly against human immunodeficiency virus (HIV), and although several viral proteins have been shown to deregulate IFN induction, little is known about the induction of type I IFNs by HIV RNAs. In the present study, we used the stable isotope labeling with amino acids in cell culture (SILAC) method to determine the proteomic profile in U937 monocytic cells after transfection with viral RNA of HIV. We then used a western blot assay to validate the proteomic results. It was revealed by the SILAC method that there were 1624 non-redundant peptides with quantitative information and 281 proteins with quantitative information in the HIV-RNA-transfected U937 cells when compared to cells transfected with control RNA. In particular, 6, 8 or 12 hours post-transfection, HIV RNA transfection promoted the expression of such interferon stimulated genes (ISGs) as interferon-induced proteins with tetratricopeptide repeats (IFITs), interferon-induced transmembrane proteins (IFITMs), interferon-induced gene 15 protein (ISG15), myxovirus (influenza virus) resistance protein 1 (MX1), and interferon-induced guanylate-binding protein 1 (GBP1), and this was confirmed by western blot assay. In conclusion, HIV RNA is a strong stimulator of IFNs, promoting the expression of such ISGs as IFITs, IFITMs, ISG15, MX1 and GBP1.

Beta interferon regulation of glucose metabolism is PI3K/Akt dependent and important for antiviral activity against coxsackievirus B3

An effective type I interferon (IFN)-mediated immune response requires the rapid expression of antiviral proteins that are necessary to inhibit viral replication and virus spread. We provide evidence that IFN-β regulates metabolic events important for the induction of a rapid antiviral response: IFN-β decreases the phosphorylation of AMP-activated protein kinase (AMPK), coincident with an increase in intracellular ATP. Our studies reveal a biphasic IFN-β-inducible uptake of glucose by cells, mediated by phosphatidylinositol 3-kinase (PI3K)/Akt, and IFN-β-inducible regulation of GLUT4 translocation to the cell surface. Additionally, we provide evidence that IFN-β-regulated glycolytic metabolism is important for the acute induction of an antiviral response during infection with coxsackievirus B3 (CVB3). Last, we demonstrate that the antidiabetic drug metformin enhances the antiviral potency of IFN-β against CVB3 both in vitro and in vivo. Taken together, these findings highlight an important role for IFN-β in modulating glucose metabolism during a virus infection and suggest that the use of metformin in combination with IFN-β during acute virus infection may result in enhanced antiviral responses.

IMPORTANCE

Type I interferons (IFN) are critical effectors of an antiviral response. These studies describe for the first time a role for IFN-β in regulating metabolism--glucose uptake and ATP production--to meet the energy requirements of a robust cellular antiviral response. Our data suggest that IFN-β regulates glucose metabolism mediated by signaling effectors similarly to activation by insulin. Interference with IFN-β-inducible glucose metabolism diminishes the antiviral response, whereas treatment with metformin, a drug that increases insulin sensitivity, enhances the antiviral potency of IFN-β.

Mapping of the interferon gamma (IFNG) gene in river and swamp buffaloes by in situ hybridization

In situ hybridization technique was applied using a tritiated (3H) bovine IFNG cDNA probe to regionally localize the gene on river and swamp buffalo chromosomes. The hybridization signals peaked on the 4q23-->q26 bands in river buffaloes and on the 1p24-->p26 bands in swamp buffaloes. The results are compared to the localization of the same gene in cattle. Possible evolutionary conservation in the Bovidae is discussed.

Chronic myeloid leukemia

Chronic myeloid leukemia is a clonal myeloproliferative disorder of a pluripotent stem cell with a specific cytogenetic abnormality, the Philadelphia chromosome, involving myeloid, erythroid, megakaryocytic, B lymphoid, and sometimes T lymphoid cells but not marrow fibroblasts. Advances in cell biology and molecular genetics and a plethora of biochemical, cytogenetic, and molecular data of clinical relevance have yielded much new information regarding this disease. This article reviews the hematologic and clinical aspects of chronic myeloid leukemia; discusses the pertinent aspects of the advances in understanding of the cytogenetics and molecular biology of the disease; and reviews treatment programs employing busulfan, hydroxyurea, interferon, and marrow transplantation, which still are clinically important and relevant despite the development of the exciting new drug imatinib mesylate, a new paradigm for cancer chemotherapy in general.

Interferon gamma inhibits growth of human pancreatic carcinoma cells via caspase-1 dependent induction of apoptosis

BACKGROUND AND AIMS

The poor prognosis of pancreatic cancer is partly due to resistance to a broad spectrum of apoptotic stimuli. To identify intact proapoptotic pathways of potential clinical relevance, we characterised the effects of interferon gamma (IFN-gamma) on growth and survival in human pancreatic cancer cells.

METHODS

IFN-gamma receptor expression and signal transduction were examined by reverse transcriptase-polymerase chain reaction (RT-PCR), immunoprecipitation, western blot analysis, and transactivation assays. Effects on cell growth and survival were evaluated in terms of cell numbers, colony formation, cell cycle analysis, DNA fragmentation, and poly(ADP ribose) polymerase (PARP) cleavage.

RESULTS

All four pancreatic cancer cell lines examined expressed functional IFN-gamma receptors and downstream effectors, including the putative tumour suppressor interferon regulatory factor 1 (IRF-1). IFN-gamma treatment profoundly inhibited anchorage dependent and independent growth of pancreatic cancer cells. Cell cycle analyses revealed subdiploid cells suggesting apoptosis, which was confirmed by demonstration of DNA fragmentation and PARP cleavage. Time and dose dependency of apoptosis induction and growth inhibition correlated closely, identifying apoptosis as the main, if not exclusive, mechanism responsible for growth inhibition. Apoptosis was preceded by upregulation of procaspase-1 and accompanied by proteolytic activation. Furthermore, the caspase inhibitor z-vad-fmk completely prevented IFN-gamma mediated apoptosis.

CONCLUSIONS

These results identify an intact proapoptotic pathway in pancreatic cancer cells and suggest that IRF-1 and/or procaspase-1 may represent potential therapeutic targets to be further explored.

Expression of nucleotide-regulated Cl(-) currents in CF and normal mouse tracheal epithelial cell lines

The dominant route for Cl(-) secretion in mouse tracheal epithelium is via Cl(-) channels different from the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), the channel that is defective in CF. It has been proposed that the use of purinergic agonists to activate these alternative channels in human airways may be beneficial in CF. In the present study, two conditionally immortal epithelial cell lines were established from the tracheae of mice possessing the tsA58 T antigen gene, one of which [MTE18-(-/-)] was homozygous for a knockout of CFTR and the other [MTE7b-(+/-)] heterozygous for CFTR expression. In Ussing chamber studies, amiloride (10(-4) M) and a cocktail of cAMP-activating agents (forskolin, IBMX, and dibutyryl cAMP) resulted in small changes in the short-circuit current (I(sc)) and resistance of both cell lines, with larger increases in I(sc) being elicited by ionomycin (10(-6) M). Both cell lines expressed P(2)Y(2) receptors and responded to the purinergic agonists ATP, UTP, and 5'-adenylylimidodiphosphate (10(-4) M) with an increase in I(sc). This response could be inhibited by DIDS and was abolished in the presence of Cl(-)-free Ringer solution. Reducing the mucosal Cl(-) concentration increased the response to UTP of both cell lines, with a significantly greater increase in MTE18-(-/-) cells. Pretreatment of these cells with thapsigargin caused a direct increase in I(sc) and inhibited the response to UTP. These data suggest that both cell lines express purinergic-regulated Cl(-) currents and may prove valuable tools in studying the properties of this pathway.

Overproduction of gamma interferon in B/Jas inbred rabbits with herpes simplex virus encephalitis

Inbred rabbits of the B/Jas strain are highly susceptible to herpes simplex virus type-1 (HSV-1) encephalitis, developing seizures of encephalitis after intravenous injection of the KOS strain of the virus. Anti-viral interferon activity became detectable in the serum just prior to or at the onset of seizures, its level being lower in the serum than in the cerebrospinal fluid. The activity was of gamma interferon, as suggested by the acid instability and the inability of Mx protein induction. An immunohistochemical analysis of the brain tissues of encephalitic rabbits showed that MHC class I antigen was expressed on the microglia cells of inflamed lesions but not on these cells in uninflamed areas. These findings were discussed in correlation with the pathogenesis of herpetic encephalitis in the inbred rabbits.

Interferon-induced guanylate binding protein-1 (GBP-1) mediates an antiviral effect against vesicular stomatitis virus and encephalomyocarditis virus

A cDNA encoding the human guanylate binding protein-1 (hGBP-1) was expressed in HeLa cells using a constitutive expression vector. Stably transfected clones expressing hGBP-1 exhibited resistance to the cytopathic effect mediated by both vesicular stomatitis virus (VSV) and encephalomyocarditis virus (EMCV) and produced less viral progeny than control cells following infection with these viruses. To study the role hGBP-1 plays in the IFN-mediated antiviral effect, cells were stably transfected with a construct expressing antisense RNA for hGBP-1. VSV infection of IFN-alpha-treated antisense RNA-expressing cells produced an amount of virus comparable to that produced in the parental cell line, while EMCV infection of the IFN-alpha-treated transfected cells and VSV and EMCV infection of the IFN-gamma-treated transfected cells produced far more virus than was produced in the parental cell line. These results demonstrate that GBP-1 mediates an antiviral effect against VSV and EMCV and plays a role in the IFN-mediated antiviral response against these viruses.

Conditioned immune response to interferon-gamma in humans

We determined whether a classical conditioning paradigm may be used to condition immunologic responses in normal human subjects receiving an optimal immunostimulating dose of recombinant human interferon-gamma (rhIFN-gamma). We conducted a placebo-controlled, double-blind study of 31 normal volunteers in order to determine whether an initially immune-neutral stimulus, oral propylene glycol (PG), could eventually elicit an immune response as a consequence of its being paired with a known immunostimulatory dose and schedule of rhIFN-gamma. Subjects were randomly assigned to one of three groups: (A) rhIFN-gamma injections paired with PG; (B) normal saline injections paired with PG; (C) rhIFN-gamma injections alone. During the 4-week study, subjects received progressively fewer injections so that, by the final week of the study, no injections were given and groups A and B received only PG. The principal outcome measures were serum concentrations of quinolinic acid (QUIN) and neopterin, two nonspecific but sensitive markers of immune activation, and expression of Fc receptors (CD64) on peripheral blood mononuclear cells. RhIFN-gamma injections produced significant and predictable alterations in each of the measured immune parameters. No group B subject made an immune response. Mean serum QUIN levels were significantly higher at the end of week three for subjects in the experimental condition (group A) than for subjects receiving rhIFN-gamma alone (group C) despite receiving identical doses of rhIFN-gamma. Similarly, the predicted decay in mean serum neopterin levels from the end of week 1 to the end of week 2 was seen in group C but not in group A. The exposure of group A to PG blunted the decline of CD64 expression in week four. The data suggest that the pairing of an unconditioned stimulus (rhIFN-gamma) and a conditioned stimulus (PG) permits the conditioned stimulus alone to prolong a cytokine-induced response in normal humans.

Multiple effects of transfection with interleukin 2 and/or interferon gamma on the behavior of mouse T lymphoma cells

We have previously reported that transfection of mouse interferon gamma (IFN-gamma) in H-2Kk-positive BW variants (BW-Sp3) abolishes tumorigenicity and reduces metastatic capacity. To further increase the immunogenicity of BW-Sp3 cells, the gene for human interleukin 2 (huIL-2) was transfected in these cancer cells. Single BW-Sp3(huIL-2) and double BW-Sp3(huIL-2+IFN-gamma) transfectants were generated and their behavior was investigated as compared to parental and IFN-gamma-transfected BW-Sp3. Although expression of huIL-2 was equally effective as IFN-gamma in preventing tumor formation and reducing experimental metastasis, it did not confer protection to spontaneous metastases and even reversed the anti-metastatic activity of IFN-gamma. Inoculation of the BW variants in immunocompromised mice revealed that expression of IL-2 activates both T cells and aspecific immune effectors. However, in immunocompromised mice a clear pro-metastatic effect of IL-2 was recorded. Analysis of membrane antigens on the different variants showed a selective effect of huIL-2 on the expression of two surface antigens, i.e. L-selectin and metastatic T cell hybridoma antigen (MTH), which may contribute to metastasis. Hence upon expression of huIL-2 in T lymphoma variants, tumor outcome will depend on the balanced effects of the transfected cytokines on the immune response and the redirected effect on tumor progression.

Reoviruses and the interferon system

Reovirus induces IFN, and reovirus is sensitive to the antiviral actions of IFN. The characteristics of the IFN-inducing capacity of reovirus, and the antiviral actions of IFN exerted against reovirus, are dependent upon the specific combination of reovirus strain, host cell line, and IFN type. Responses, both IFN induction and IFN action, differ quantitatively if not qualitatively and are dependent upon the virus, cell, and IFN combination. Stable natural dsRNA, identified as the form of nucleic acid that constitutes the reovirus genome, is centrally involved in the function of at least three IFN-induced enzymes. Protein phosphorylation by PKR, RNA editing by the ADAR adenosine deaminase, and RNA degradation by the 2',5'-oligoA pathway all involve dsRNA either as an effector or as a substrate. Considerable evidence implicates PKR as a particularly important contributor to the IFN-induced antiviral state displayed at the level of the single virus-infected cell, where the translation of viral mRNA is often observed to be inhibited following treatment with IFN-alpha/beta. In the whole animal infected with reovirus, elevated cellular immune responses mediated by enhanced expression of MHC class I and class II antigens induced by IFN-alpha/beta or IFN-gamma may contribute significantly to the overall antiviral response.

Immune response to mouse mammary tumor virus in mice lacking the alpha/beta interferon or the gamma interferon receptor

Mouse mammary tumor virus (MMTV) is a retrovirus which induces a strong immune response and a dramatic increase in the number of infected cells through the expression of a superantigen (SAg). Many cytokines are likely to be involved in the interaction between MMTV and the immune system. In particular, alpha/beta interferon (IFN-alpha/beta) and gamma interferon (IFN-gamma) exert many antiviral and immunomodulatory activities and play a critical role in other viral infections. In this study, we have investigated the importance of interferons during MMTV infection by using mice with a disrupted IFN-alpha/beta or IFN-gamma receptor gene. We found that the SAg response to MMTV was not modified in IFN-alpha/betaR(0/0) and IFN-gammaR(0/0) mice. This was true both for the early expansion of B and T cells induced by the SAg and for the deletion of SAg-reactive cells at later stages of the infection. In addition, no increase in the amount of proviral DNA was detected in tissues of IFN-alpha/betaR(0/0) and IFN-gammaR(0/0) mice, suggesting that interferons are not essential antiviral defense mechanisms during MMTV infection. In contrast, IFN-gammaR(0/0) mice had increased amounts of IL-4 mRNA and an altered usage of immunoglobulin isotypes with a reduced frequency of IgG2a- and IgG3-producing cells. This was associated with lower titers of virus-specific antibodies in serum early after infection, although efficient titers were reached later.

Effects of intranasal administration of recombinant murine interferon-gamma on murine acute myocarditis caused by encephalomyocarditis virus

BACKGROUND

Viral myocarditis has been strongly implicated in the pathogenesis of dilated cardiomyopathy as well as acute myocarditis. Among the antiviral therapies, interferons (IFNs) have been widely studied and become very important in clinical practice.

METHODS AND RESULTS

To investigate the possibilities of IFN therapy in viral myocarditis, we analyzed the effects of recombinant murine interferon (mIFN)-gamma and natural mIFN-alpha/beta by the intranasal and intramuscular routes on the development of acute murine myocarditis caused by encephalomyocarditis virus. Both mIFN-gamma and mIFN-alpha/beta treatment by either route significantly increased the survival rate; none of the mIFN-gamma-treated mice died. The effect of mIFN-gamma was significantly greater than that of mIFN-alpha/beta. Furthermore, intranasal administration of mIFN-gamma significantly suppressed virus replication and inflammation in the heart.

CONCLUSIONS

Our data demonstrate that IFN therapy, especially intranasal administration of IFN-gamma, dramatically improved the prognosis of acute murine viral myocarditis by suppressing virus replication and raises the possibility of antiviral therapy with IFN-gamma in patients with acute myocarditis.

HIV p17 enhances lymphocyte proliferation and HIV-1 replication after binding to a human serum factor

OBJECTIVE

To analyse the role of recombinant HIV-1 protein p17 in the modulation of cell activity.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence or absence of p17 with mitogens such as phytohaemagglutinin or interleukin-2 and their response assayed by cell proliferation. Cross-linking experiments were employed to investigate the presence of a binding between p17 and factor(s) present in human serum. An immunoenzymatic assay for p24 antigen detection was used to analyse the effect of the addition of exogenous p17 to cultures of PBMC infected with HIV-1 in vitro.

RESULTS

Purified recombinant p17 protein at a concentration of 0.25 microg/ml significantly increased the proliferation of preactivated PBMC obtained from healthy donors. This effect was obtained by binding p17 to factor(s) present in human serum and observed on both CD4+ and CD8+ T cells. Recombinant p17 also induced an increased rate of HIV-1 replication, probably due to enhanced T-cell proliferation. The activity of p17 protein was inhibited by anti-p17 antibodies generated by injecting recombinant p17 in rabbits, but not by human antibodies generated during the natural course of HIV infection.

CONCLUSION

Characterization of the human factor(s) and identification of the interacting p17 epitope(s) will improve our understanding of the mechanisms used by HIV to efficiently replicate in our organisms.

Effects of retinoic acid combined with interferon-gamma on the expression of major-histocompatibility-complex molecules and intercellular adhesion molecule-1 in human cervical cancer

Retinoids and interferons are important regulators of human epithelial cell differentiation and have been successfully used in the clinical treatment of HPV-involved cervical cancer. In this study, 2 HPV-positive human cervical-carcinoma cell lines were analyzed for their surface expression of MHC-Class-I, MHC-Class-II and ICAM-1 surface antigens before and after exposure to all-trans retinoic acid, interferon-gamma and the combination of the 2 compounds. In addition, the effects on HLA-Class-I-mRNA expression were evaluated after such treatments. Both cell lines expressed MHC-Class-I molecules, and their levels were markedly up-regulated after exposure to IFN-gamma. Similarly, MHC-Class-II and ICAM-1 antigens were either induced or significantly up-regulated by IFN-gamma. Exposure to all-trans retinoic acid was also able to significantly increase the expression of MHC-Class-I and ICAM-I antigens as compared with untreated tumor cells. However, unlike IFN-gamma, retinoids were not able to induce the expression of HLA-Class-II surface antigens. Exposure to the combination of IFN-gamma plus retinoic acid significantly up-regulated (in an additive manner) HLA-Class-I and ICAM-1 molecules as compared with the levels obtainable after exposure to IFN-gamma alone. Finally, Northern-blot analysis of HLA-Class-I-mRNA expression confirmed that the activity of both of these biologic response modifiers was at transcriptional level. These data indicate that the combination of these modalities could induce an additive effect on the expression of immunologically important surface antigens on human cervical-cancer cells. These findings, together with the known anti-proliferative effects mediated by retinoids and IFN-gamma on tumor cells, further support the combination of these agents in the treatment of pre-invasive and invasive human cervical cancer.

Interferon γ Downregulates Stem Cell Factor and Erythropoietin Receptors But Not Insulin-Like Growth Factor-I Receptors in Human Erythroid Colony-Forming Cells

Interferon γ (IFNγ) has been shown to inhibit proliferation and differentiation of erythroid progenitor cells and to produce apoptosis of erythroid cells, whereas stem cell factor (SCF ), erythropoietin (EP), and insulin-like growth factor-I (IGF-I) have distinct roles in enhancing erythroid cell production and preventing apoptosis. The mechanism by which IFNγ exerts an inhibitory effect on the positive roles of these growth factors is unknown. Although some inhibitory cytokines including IFNγ have been shown to downregulate growth factor receptors, the effect of IFNγ on SCF, EP, and IGF-I receptors of human erythroid progenitor cells has not been defined. We obtained highly purified day-5 or day-6 erythroid colony-forming cells (ECFCs) from human blood in sufficient quantity and purity for radiolabeled cytokine binding studies and analysis of mRNA. When day-5 ECFCs were incubated with increasing concentrations of recombinant human (rh) IFNγ for 24 hours at 37°C, specific binding of 125I-rhSCF to SCF receptors was significantly decreased by 25% to 40% in a dose-dependent fashion, with the maximum effect at 2,500 to 5,000 U/mL of IFNγ. The decrease was apparent by 12 hours of incubation and was only slightly lower by 24 hours. The numbers of SCF and EP receptors, but not of IGF-I receptors, per ECFC, calculated by Scatchard analysis, were significantly decreased by 30% and 23% to 25%, respectively, after incubation with 2,500 U/mL rhIFNγ for 24 hours at 37°C, whereas the binding affinities were not affected. This decrease in SCF receptors was confirmed by flow cytometry using an anti–c-kit mouse monoclonal antibody. Northern blot analysis showed that the mRNAs for the SCF and EP receptors, but not for the IGF-I receptors, were decreased by 50% to 60% after 3 hours of incubation at 37°C with 2,500 U/mL of rhIFNγ. This persisted for 24 hours without alteration of the stability of the SCF and EP receptor mRNAs. These observations suggest that one means by which IFNγ inhibits erythroid cell proliferation and differentiation and produces apoptosis may be through the reduction of the number of target receptors for SCF and EP and that this occurs through transcriptional inhibition of the corresponding mRNAs.

Interferon γ Downregulates Stem Cell Factor and Erythropoietin Receptors But Not Insulin-Like Growth Factor-I Receptors in Human Erythroid Colony-Forming Cells

Interferon γ (IFNγ) has been shown to inhibit proliferation and differentiation of erythroid progenitor cells and to produce apoptosis of erythroid cells, whereas stem cell factor (SCF ), erythropoietin (EP), and insulin-like growth factor-I (IGF-I) have distinct roles in enhancing erythroid cell production and preventing apoptosis. The mechanism by which IFNγ exerts an inhibitory effect on the positive roles of these growth factors is unknown. Although some inhibitory cytokines including IFNγ have been shown to downregulate growth factor receptors, the effect of IFNγ on SCF, EP, and IGF-I receptors of human erythroid progenitor cells has not been defined. We obtained highly purified day-5 or day-6 erythroid colony-forming cells (ECFCs) from human blood in sufficient quantity and purity for radiolabeled cytokine binding studies and analysis of mRNA. When day-5 ECFCs were incubated with increasing concentrations of recombinant human (rh) IFNγ for 24 hours at 37°C, specific binding of 125I-rhSCF to SCF receptors was significantly decreased by 25% to 40% in a dose-dependent fashion, with the maximum effect at 2,500 to 5,000 U/mL of IFNγ. The decrease was apparent by 12 hours of incubation and was only slightly lower by 24 hours. The numbers of SCF and EP receptors, but not of IGF-I receptors, per ECFC, calculated by Scatchard analysis, were significantly decreased by 30% and 23% to 25%, respectively, after incubation with 2,500 U/mL rhIFNγ for 24 hours at 37°C, whereas the binding affinities were not affected. This decrease in SCF receptors was confirmed by flow cytometry using an anti–c-kit mouse monoclonal antibody. Northern blot analysis showed that the mRNAs for the SCF and EP receptors, but not for the IGF-I receptors, were decreased by 50% to 60% after 3 hours of incubation at 37°C with 2,500 U/mL of rhIFNγ. This persisted for 24 hours without alteration of the stability of the SCF and EP receptor mRNAs. These observations suggest that one means by which IFNγ inhibits erythroid cell proliferation and differentiation and produces apoptosis may be through the reduction of the number of target receptors for SCF and EP and that this occurs through transcriptional inhibition of the corresponding mRNAs.

Treatment of experimental autoimmune encephalomyelitis by feeding myelin basic protein conjugated to cholera toxin B subunit

Oral administration of autoantigens can prevent and partially suppress autoimmune diseases in a number of experimental models, Depending on the dose of antigen fed, this approach appears to involve distinct yet reversible and short-lasting mechanisms (anergy/deletion and suppression) and usually requires repeated feeding of large (suppression) to massive (anergy/deletion) amounts of autoantigens to be effective. Most importantly, this approach is relatively less effective in animals already systemically sensitized to the fed antigen, such as in animals already harboring autoreactive T cells and, thus, presumably also in humans suffering from an autoimmune disorder. We have previously shown that feeding a single dose of minute amounts of antigens conjugated to cholera toxin B subunit (CTB) can effectively suppress delayed-type hypersensitivity reactions in systemically immune animals. We now report that feeding small amounts of myelin basic protein (MBP) conjugated to CTB either before or after disease induction protected rats from experimental autoimmune encephalomyelitis. Such treatment was as effective in suppressing interleukin 2 production and proliferative responses of lymph node cells to MBP as treatment involving repeated feeding with much larger (50- to 100-fold) doses of free MBP. Different from the latter treatment, which led to decreased production of interferon-gamma in lymph nodes, low-dose oral CTB-MBP treatment was associated with increased interferon-gamma production. Most importantly, low-dose oral CTB-MBP treatment greatly reduced the level of leukocyte infiltration into spinal cord tissue compared with treatment with repeated feeding of large doses of MBP. These results suggest that the protection from experimental autoimmune encephalomyelitis achieved by feeding CTB-conjugated myelin autoantigen involves immunomodulating mechanisms that are distinct from those implicated by conventional protocols of oral tolerance induction.

Tumor necrosis factor-alpha and interferon-gamma inhibit synergistically viral replication in hepatitis B virus-replicating cells

The effects of tumor necrosis factor-alpha and/or interferon-gamma on the replication of hepatitis B virus were examined using HB611 cells. These cells were derived from human hepatoblastoma cells, Huh6, by integrating hepatitis B virus DNA, and produce hepatitis B virus continuously. Each of the cytokines inhibited hepatitis B virus replication in the cells assessed as the amount of episomal hepatitis B virus DNA, without a decrease in cell viability. When the two cytokines were administered together, the inhibitory effect became greater. Incubation of the cells with 1,000 U/ml tumor necrosis factor-alpha decreased HBV DNA replicative intermediates by 55%, and that with 1,000 U/ml interferon-gamma decreased these by 51%. Furthermore, incubation with 1,000 U/ml tumor necrosis factor-alpha and 1,000 U/ml interferon-gamma in combination decreased HBV DNA replicative intermediates by 71%. In contrast, the amount of hepatitis B virus RNA and secretion of hepatitis B e antigen were not apparently reduced by the cytokines, and 2',5'-oligoadenylate synthetase activity was not detected in the supernatant. These results suggest that tumor necrosis factor-alpha and interferon-gamma inhibit hepatitis B virus replication by blocking some step in reverse transcription and that the 2',5'-oligoadenylate synthetase is not involved in the mechanism underlying the inhibition by these two cytokines.

Systemic and hemodynamic effects of recombinant tumor necrosis factor alpha in isolation perfusion of the limbs

OBJECTIVE

To describe the systemic effects of high-dose recombinant tumor necrosis factor alpha (rTNF-alpha), recombinant interferon gamma (rIFN-gamma), and melphalan administered through hyperthermic isolation perfusion of the limbs (IPL) in patients with melanoma and malignant soft-tissue tumors.

DESIGN

The clinical, hemodynamic, and biologic parameters were recorded after IPL during the postoperative period.

SETTING

Surgical intensive care service of a 1,000-bed tertiary university medical center.

PATIENTS

Nineteen patients referred to a pluridisciplinary Center for Oncology after relapse of regionally advanced melanoma or soft-tissues tumors, included in a phase 2 therapeutic study.

RESULTS

Major systemic and hemodynamic changes were observed after IPL in all patients. Ninety-four percent (17/18) of the evaluable patients presented a shock unresponsive to fluid challenge, requiring the continuous perfusion of vasopressors, inotropic agents, or both. Analysis of hemodynamic data showed two distinctive patterns: a pure distributive shock in nine patients requiring norepinephrine, and a mixed distributive and cardiogenic shock in eight patients requiring vasopressor and inotropic agents. The oxygen parameters were characterized by an increase in both the delivery and the uptake of oxygen, with a prolonged reduced oxygen extraction ratio for most patients. The other observed effects were as follows: transient bilateral or mixed pulmonary infiltrates in all patients; some hematologic disturbances in 83% of patients; infection requiring a modification of the antibiotic prophylaxis in 61% of patients; and some liver toxic reactions in 50% of patients. Very high systemic TNF-alpha serum bioactivity was found in 12 patients for whom serum samples were available, indicating an early and important rTNF-alpha leakage from the IPL. No correlations could be found between the levels of TNF-alpha and the observed systemic effects. Despite the severity of the hemodynamic disturbance, no patient died.

CONCLUSION

Major systemic effects, consisting mainly in cardiovascular, respiratory, and hematologic disturbances, were observed in patients after IPL with high-dose of rTNF-alpha. The likely explanation for these observations is an early rTNF-alpha leakage related to inadequate IPL technique. These data show that the iatrogenic administration of high circulating TNF levels lead to a "septic shock-like" syndrome without resulting in lethal organ dysfunction.

A monoclonal antibody to the NH2-terminal region of human interferon-gamma inhibits its antiproliferative activity without affecting its internalization

MAb IGMB-15, an anti-hIFN-gamma MAb, neutralizes the antiproliferative activity of hIFN-gamma without affecting that of hIFN-alpha or hIFN-beta. The neutralizing capacity of MAb IGMB-15 is wide: it has been assessed on cell lines whose origin and sensitivity to hIFN-gamma differ. The binding of hIFN-gamma to its receptor and its subsequent internalization into the target cell were not influenced by the antibody. MAb IGMB-15 has been found to interact with hIFN-gamma in solution but not when the lymphokine was associated with its cell surface receptor, showing that the growth of certain cell lines can be inhibited at the cell membrane level. This finding is consistent with the existence of an accessory factor responsible for the antiproliferative activity of hIFN-gamma.

Expression of the interferon-gamma receptor gene in mouse placentas is related to stage of gestation and is restricted to specific subpopulations of trophoblast cells

In order to evaluate the potential of placental cells to bind the multifunctional cytokine, interferon-gamma (IFN-gamma), tissues collected from pregnant Swiss mice were analysed for IFN-gamma receptor (IFN-gamma R) mRNA and protein. Northern blot hybridization studies indicated that the relative abundance of IFN-gamma R mRNA increased as gestation progressed to term. Analysis by in situ hybridization revealed that trophoblast cells first contained high steady state levels of IFN-gamma R mRNA at g.d. 12. At g.d. 12 and 14, transcription was restricted to cells in the spongiotrophoblast region and nests of similar cells in the labyrinthine region. These cells also contained immunoreactive IFN-gamma R protein. By g.d. 18, IFN-gamma R mRNA was clearly detectable in large spongiotrophoblast cells and labyrinthine trophoblast. IFN-gamma R mRNA was low to absent in giant trophoblast cells at all stages of gestation. Specific mRNA was present in parietal and visceral yolk sac cells by g.d. 14. Thus, expression of the IFN-gamma R gene in mouse placental cells is influenced by stage of gestation, cell lineage and state of differentiation. Whether or not these cells respond vigorously to IFN-gamma with induction of antiviral proteins, increased MHC class I antigens and growth modulation may therefore be determined by their expression of specific receptors for this pluripotent cytokine.

Antitumor response to recombinant murine interferon gamma correlates with enhanced immune function of organ-associated, but not recirculating cytolytic T lymphocytes and macrophages

The mechanism of therapeutic activity for recombinant murine interferon-gamma (rMu IFN gamma) in the treatment of metastatic disease was investigated by comparing effector cell augmentation with therapeutic activity in mice bearing experimental lung metastases (B16-BL6 melanoma). Effector cell functions in spleen, peripheral blood, and lung (the tumor-bearing organ) were tested after 1 week and 3 weeks of rMu IFN gamma administration (i.v. three times per week). Natural killer (NK), lymphokine-activated killer (LAK), cytolytic T lymphocyte (CTL) activities against specific and nonspecific targets, and macrophage tumoristatic activity were measured. rMu IFN gamma demonstrated immunomodulatory activity in most assays of immune function. The optimal therapeutic protocol of rMu IFN gamma (2.5 x 10(6) U/kg, three times per week) prolonged survival and decreased the number of pulmonary metastatic foci. This therapeutic activity was correlated with specific CTL activity from pulmonary parenchymal mononuclear cells (PPMC), but not from spleen or blood. Macrophage tumoristatic activity in PPMC also correlated with therapeutic activity, but activity in alveolar macrophages did not. However, therapeutic activity did not correlate with NK or LAK activity at any site. These results demonstrate that the optimal therapeutic protocol is the same as the optimal immunomodulatory dose for pulmonary CTL and macrophage activities. Furthermore, while immunological monitoring may help to optimize treatment protocols, current monitoring procedures that use readily accessible sites, particularly peripheral blood, may not accurately predict the therapeutic efficacy of biological response modifiers in clinical trials.

Interferon-alpha and interferon-gamma induced modulation of proteins in human corneal fibroblasts

Little is known about the effects of interferon (IFN) on cell function in the eye. We have analyzed the effect of INF-alpha and IFN-gamma on the expression of proteins in cultured human corneal fibroblasts. Treatment with IFN-alpha increased the synthesis of proteins of 84, 76, 52, and 28 kD and decreased the synthesis of a 72-kD protein. Treatment with IFN-gamma increased the synthesis of proteins of 83, 66, 64, 54, and 47 kD. The effect of IFN-alpha and IFN-gamma were first detected at 5-9 h and 9 h, respectively, after the addition of the IFNs and were maximal at 17 and 24 h, respectively. Most of the changes were seen at doses of 1 x 10(1) to 1 x 10(2) U/ml of IFN-alpha or IFN-gamma and were maximal at 1 x 10(2) to 1 x 10(3) U/ml. Thus, each IFN induced distinct proteins based on apparent molecular weight and isoelectric point. These results show that IFN-alpha and IFN-gamma affect the synthesis of small groups of distinct proteins in human corneal fibroblasts.

Inhibition of duck hepatitis B virus replication by interferon-gamma

Interferons have been evaluated extensively as candidate antiviral agents in hepadnaviral infection. We examined the effect of recombinant human interferon-gamma on duck hepatitis B virus replication in human hepatoma cells (Huh 7) transiently transfected with cloned duck hepatitis B virus DNA. Cells transfected in the presence of interferon-gamma display a dose-dependent reduction in the levels of encapsidated replicative intermediates in the cytoplasm, as judged by Southern blotting of purified viral core DNA. The effect is observed at interferon-gamma concentrations that do not affect growth rate or viability of Huh 7 cells or their transfection efficiency. Northern analysis of duck hepatitis B virus transcripts in transfected cells demonstrated markedly diminished levels of pre- and subgenomic RNA in interferon-gamma-treated cells. Nuclear run-on analysis was performed to determine whether these transcripts were diminished due to decreased rates of transcription initiation or increased rates of RNA degradation. Levels of transcription initiation were unaffected by interferon-gamma, implying that duck hepatitis B virus transcripts in interferon-gamma-treated cells are degraded more rapidly than in untreated cells.

Interferon-gamma inhibits DNA synthesis and insulin-like growth factor-II expression in human neuroblastoma cells

Interferon-gamma (IFN-gamma) is known to be an antiproliferative, differentiating agent in many cell types, including neuroblastoma. In this study, we determined the effects of IFN-gamma on cellular growth and expression of insulin-like growth factor II (IGF-II) and IGF receptors in the human neuroblastoma cell line SH-SY5Y. Incubation of SH-SY5Y cells in IFN-gamma (20-100 U/ml) induced the formation of long neuritic processes. IFN-gamma treatment also induced decreases in [3H]TdR incorporation, as well as serum-dependent changes in cell number. Treatment with IFN-gamma reduced cell number 33% in the presence of serum but had no effect on cell number in the absence of serum. IGF-II mRNA content was 60% inhibited by IFN-gamma, and was not serum dependent. The concentration of immunoreactive IGF-II in SH-SY5Y conditioned medium was also reduced in the presence of IFN-gamma, to less than half of control levels. In contrast, type I IGF receptor mRNA content was increased more than three-fold after treatment with IFN-gamma and serum. Co-incubation in IFN-gamma (20-100 U/ml) and IGF-II (3-10 nM) prevented the inhibitory effects of IFN-gamma on [3H]TdR incorporation in serum-free media. Our results suggest that IFN-gamma may inhibit DNA synthesis and cell growth by interfering with an IGF-II/type I IGF receptor autocrine growth or survival mechanism.

Pharmacokinetics of recombinant human interferon-beta ser in healthy volunteers and its effect on serum neopterin

The pharmacokinetics of and biologic response modification by recombinant human interferon-beta ser (rIFN-beta ser) were evaluated in 12 healthy male volunteers. Subjects received a single intravenous (iv) injection of 90 x 10(6) IU of rIFN-beta ser followed by a single or eight consecutive daily 90 x 10(6) IU subcutaneous (sc) doses. Blood samples collected after the iv, first sc, and last sc doses and prior to each sc dose were assayed for interferon antiviral activity and the interferon-inducible marker neopterin. Following iv administration, serum interferon concentrations generally declined biexponentially, with a mean serum clearance of 0.76 +/- 0.28 L/hr-kg, a mean steady-state volume of distribution of 2.88 +/- 1.81 L/kg, and a mean terminal half-life of 4.29 +/- 2.29 hr as determined by noncompartmental analysis. Following sc administration, absorption of rIFN-beta ser was prolonged, with serum concentrations generally below 100 IU/mL. No accumulation of rIFN-beta ser in serum was noted after eight daily sc injections. In contrast, serum neopterin levels did not increase above baseline levels until 12 hr after iv dosing and 24 hr after sc dosing. The mean increase in serum neopterin at 24 hr post iv injection was significantly greater than that at 24 hr post sc dosing.

Phase II trial of recombinant interferon gamma in refractory undifferentiated carcinoma of the nasopharynx

The presence of Epstein-Barr virus (EBV) genomes in the DNA of tumor cells of undifferentiated carcinoma of nasopharyngeal type (UCNT), associated with significant lymphocytic infiltration of tumor led to therapeutic trials with interferon (IFN) because of its antiviral, antiproliferative, and immunomodulatory properties. Fourteen patients with histologically proven UCNT (2 had locoregional disease alone and 12 metastatic disease) who were refractory to conventional chemotherapy, were treated with IFN gamma 20 x 10(6) U twice a week. Treatment was well tolerated. No objective response were achieved in the 13 evaluated patients, and all patients progressed after a median treatment duration of 10 weeks (6-32). IFN gamma seems unable to induce antitumor activity alone in such heavily pretreated patients. Its possible place in the management of UCNT is probably earlier in the natural history of this disease.

Production, purification and characterization of recombinant human interferon gamma

An essentially three-step chromatographic purification procedure, i.e., ion-exchange, immobilized metal ion affinity and size-exclusion chromatography, is described for the purification to homogeneity of recombinant human interferon-gamma (rhIFN-gamma) from the inclusion bodies produced in genetically transformed Escherichia coli cells. Batchwise adsorption of the cloudy solution of renatured rhIFN-gamma obviated the need for high-speed centrifugation to clarify the suspension. This step effectively removed about 70% of extraneous protein impurities. The established purification process is reproducible and leads to a total recovery of 32%. Pilot-scale processing of E. coli cells grown in a 30-l fermentor gave about 70 mg of a homogeneous preparation of rhIFN-gamma. The specific biological activity of purified rhIFN-gamma is ca. 3.4 x 10(7) I.U./mg protein, which is comparable to that of its natural counterpart. It is basic protein (pI greater than pH 9) with a monomer relative molecular mass of 15,000. It behaves, however, as a dimer on size-exclusion chromatography. Its partial NH2-terminal sequence is identical with that established for the rhIFN-gamma. However, its amino acid composition and its relative molecular mass (15,067 as determined by electrospray mass spectrometry) indicate that the purified protein is a truncated form lacking fifteen amino acid residues from its carboxyl-terminal side. This modification does not seem to have any adverse effect on its biological potency. The levels of DNA, bacterial endotoxins and Ni(II) ions in the final product were determined.

A collection of mRNA species that are inducible in the RAW 264.7 mouse macrophage cell line by gamma interferon and other agents

To identify genes induced during macrophage activation, a cDNA library was prepared from cultures of the RAW 264.7 mouse macrophage cell line that had been treated with conditioned medium from mitogen-stimulated spleen cells, and the cDNA library was screened by differential plaque hybridization. Eleven cDNA clones, designated CRG-1 through CRG-11, corresponding to mRNA species inducible in RAW 264.7 cells by the spleen cell conditioned medium, were isolated. Inductions were not blocked by cycloheximide. All of the mRNAs were inducible by gamma interferon, and some were also inducible by alpha and beta interferons, by lipopolysaccharide, by phorbol 12-myristate 13-acetate, and by the calcium ionophore A23187. Sequencing of the cDNAs revealed that CRG-1, CRG-3, and CRG-5 are cDNAs of recently identified transcription factors IRF-1, zif/268, and LRF-1 respectively. As previously reported, CRG-2 and CRG-10 (MIG) encode new members of the platelet factor 4 family of cytokines. CRG-6 corresponds to a new member of a family of interferon-inducible genes clustered on mouse chromosome 1, CRG-9 corresponds to a prostaglandin synthase homolog, CRG-8 corresponds to beta 2-microglobulin, and CRG-4 corresponds to metallothionein II. CRG-11 contains sequences of a truncated L1Md repetitive element as well as nonrepetitive sequences. The nonrepetitive sequence of CRG-11 as well as the sequences of CRG-7 are not closely related to published sequences. The CRG genes and proteins are of interest because of their involvement in macrophage activation, because of their roles as mediators of the effects of gamma interferon and other pleiotropic agents, and because of their usefulness as tools for studying the signal pathways through which gamma interferon and other inducers exert their effects on gene and protein expression.

A collection of mRNA species that are inducible in the RAW 264.7 mouse macrophage cell line by gamma interferon and other agents

To identify genes induced during macrophage activation, a cDNA library was prepared from cultures of the RAW 264.7 mouse macrophage cell line that had been treated with conditioned medium from mitogen-stimulated spleen cells, and the cDNA library was screened by differential plaque hybridization. Eleven cDNA clones, designated CRG-1 through CRG-11, corresponding to mRNA species inducible in RAW 264.7 cells by the spleen cell conditioned medium, were isolated. Inductions were not blocked by cycloheximide. All of the mRNAs were inducible by gamma interferon, and some were also inducible by alpha and beta interferons, by lipopolysaccharide, by phorbol 12-myristate 13-acetate, and by the calcium ionophore A23187. Sequencing of the cDNAs revealed that CRG-1, CRG-3, and CRG-5 are cDNAs of recently identified transcription factors IRF-1, zif/268, and LRF-1 respectively. As previously reported, CRG-2 and CRG-10 (MIG) encode new members of the platelet factor 4 family of cytokines. CRG-6 corresponds to a new member of a family of interferon-inducible genes clustered on mouse chromosome 1, CRG-9 corresponds to a prostaglandin synthase homolog, CRG-8 corresponds to beta 2-microglobulin, and CRG-4 corresponds to metallothionein II. CRG-11 contains sequences of a truncated L1Md repetitive element as well as nonrepetitive sequences. The nonrepetitive sequence of CRG-11 as well as the sequences of CRG-7 are not closely related to published sequences. The CRG genes and proteins are of interest because of their involvement in macrophage activation, because of their roles as mediators of the effects of gamma interferon and other pleiotropic agents, and because of their usefulness as tools for studying the signal pathways through which gamma interferon and other inducers exert their effects on gene and protein expression.

Prolonged interferon-gamma application by subcutaneous infusion in cancer patients: differential response of serum CD14, neopterin, and monocyte HLA class I and II antigens

This study reports on biological response modification induced by prolonged continuous subcutaneous (s.c.) infusion of recombinant interferon-gamma (rIFN-gamma) with particular attention to changes of soluble CD14. This glycoprotein with an unknown function is derived from myeloid cells carrying membrane CD14, which is the receptor for lipopolysaccharide (LPS)-LPS-binding protein (LBP) complexes. Fifteen metastatic cancer patients received weekly escalating doses of rIFN-gamma starting at either 50 or 100 micrograms/24 h and increasing up to 400 micrograms/24 h for a median duration of 6 weeks. The maximum tolerated dose was higher (200 micrograms/24 h) with the lower (50 micrograms/24 h) starting dose. Biological activity of rIFN-gamma was evaluated by weekly measurements of CD14, neopterin, and beta 2-microglobulin concentrations in serum as well as monocyte HLA class I and II antigen expression and tumor cytotoxicity. Serum IFN-gamma concentrations increased 20-fold within 4 weeks of therapy. The levels were correlated to the mean dose (r = 0.95, p less than 0.05). Among the biological markers, two patterns were observed. First, serum CD14 concentration and expression of monocyte HLA class II antigens increased significantly during the first week, and marker expression correlated with serum IFN-gamma levels (p less than 0.05); CD14 and HLA class II antigens thereafter returned to pretreatment levels within 4 weeks of therapy despite persistently elevated serum IFN-gamma concentrations. Second, serum neopterin and beta 2-microglobulin concentrations as well as monocyte HLA class I expression also increased significantly within the first week, but remained elevated thereafter without any further dose relationship.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and biologic effects of combination therapy with gamma-interferon and tumor necrosis factor

Tumor necrosis factor (TNF) and gamma-interferon (gamma-IFN) are cytokines with synergistic biologic and antiproliferative effects in vitro and in mouse models. The biologic effects of the combination of TNF and gamma-IFN, however, have not been studied well in humans. A Phase I trial was conducted of TNF and gamma-IFN therapy in 24 patients with advanced malignancies to determine the tolerability of the combination and the biologic effects of TNF and gamma-IFN in vivo. Both TNF and gamma-IFN were administered as 30-minute intravenous infusions three times per week. Doses of TNF ranged from 25 to 100 micrograms/m2; all patients received 100 micrograms/m2 of gamma-IFN. Dose-limiting toxicity consisted primarily of orthostatic hypotension and constitutional symptoms. The maximum tolerated dose level (MTDL) of 50 micrograms/m2 of TNF and 100 micrograms/m2 of IFN-gamma was less than the maximum tolerated dose (MTD) observed in previous Phase I trials of gamma-IFN and TNF alone. Biologic responses were studied in seven patients treated at the MTDL. Serum interleukin-2 receptor levels and neopterin secretion were enhanced significantly 24 hours after therapy (P = 0.002); enhancement of monocyte Fc receptor levels had borderline statistical significance (P = 0.07). With the exception of the mean fluorescent intensity on monocytes positive for histocompatibility antigen HLA-DR (P = 0.03), HLA Class I and II cell surface protein expression was not increased. The combination significantly enhanced indoleamine dioxygenase activity and serum beta 2-microglobulin expression (P less than 0.04) but not 2',5'-oligoadenylate synthetase activity, bactericidal function, or chemiluminescence. These results were compared retrospectively with those observed in previous Phase I trials of gamma-IFN and TNF alone. The combination of TNF and gamma-IFN significantly increased urinary kynurenine levels more than either TNF alone or gamma-IFN alone. Given the limitations inherent in any retrospective analysis, however, the enhancement in the other biologic parameters measured at the MTDL during this trial did not differ significantly from the changes observed at the MTD of either TNF or gamma-IFN alone. It was concluded that the combination of TNF and gamma-IFN, when administered at the MTDL of the combination, does not offer any enhancement in biologic responses over either agent alone.

Different molecular mechanisms lead to same endpoints with different function: TNF-alpha induces non-functional CSF-1 receptors on HL-60 cells in contrast to interferon-gamma

Tumour necrosis factor-alpha (TNF-alpha) induces differentiation on human promyelocytic leukemia cells (HL-60) as assessed by growth inhibition accompanied by reduction of c-myc levels, and expression of surface colony-stimulating factor-1 (CSF-1) receptors reported as molecular markers for acute myeloid leukemia (AML). CSF-1 receptors can be readily demonstrated by direct binding of 125I-CSF-1 and expression of v-fms whose gene product retains a complete ligand binding domain. Although the same findings have been previously demonstrated on HL-60 cells after interferon-gamma (IFN-gamma) treatment, the major difference between the two pathways of cellular differentiation is the functional state of the induced receptors: when IFN-gamma is used as differentiation agent, the cells are driven to express a high number of CSF-1 receptors and are able to respond to a CSF-1 stimulus. Such mitogenic response is not obtained when TNF-alpha is applied as inducer indicating that the newly expressed receptors are not functional. This difference may be due to different molecular mechanisms the two factors trigger in order to reach the same endpoint: the maturation of this leukemic population.

A phase II study alternating alpha-2a-interferon and gamma-interferon therapy in patients with chronic myelogenous leukemia

Patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) were treated with a combination of alpha-interferon and gamma-interferon. Recombinant alpha-2a-interferon (Roferon-A, Hoffmann-LaRoche, Inc., Nutley, NJ) and recombinant gamma-interferon (Genentech, Inc., South San Francisco, CA) were administered on alternating weeks each at doses ranging from 2 to 10 MU/m2 given intramuscularly. Of the 27 patients, 11 (41%) achieved complete hematologic remission (CHR) and 3 (11%) achieved partial hematologic remission (PHR). Responses were seen among 9 of 22 (41%) patients treated during the chronic phase of the disease and in 2 of 5 (40%) patients treated during the accelerated phase/second chronic phase. Cytogenetic responses were seen in six patients, including one complete response and five minor responses. Toxicities included flu-like symptoms, which appeared to be more severe with gamma-interferon than with alpha-interferon, hypertriglyceridemia, and thrombocytopenia. In this limited study, an improved outcome was not observed for the combination regimen compared with alpha-interferon alone.

Regulation of interleukin-2 and interferon-gamma gene expression in renal failure

Regulated expression of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) genes, induced in cultured peripheral blood mononuclear cells from patients with end-stage renal disease on hemodialysis (HD; N = 13) or peritoneal dialysis (PD; N = 13), was compared to that of 32 normal donors. Culture conditions were chosen that measure the transient, phytohemagglutinin-induced expression of IL-2 and IFN-gamma messenger RNA (mRNA), as well the intactness of post-transcriptional and suppressor T cell-dependent mechanisms that control this expression. The latter was achieved by analyzing the superinduction of IL-2 and IFN-gamma mRNA occurring upon culture with cycloheximide or after low-dose gamma-irradiation, respectively. HD subjects showed a complete loss of inducibility of the IL-2 gene, concomitant with decreased inducibility of IFN-gamma mRNA. In PD subjects, by contrast, expression of IL-2 mRNA was as vigorous as in normal donors, while IFN-gamma mRNA was even more strongly inducible. This difference in gene inducibility is caused by a lack of T cell function in HD subjects. The defect in IL-2 gene expression in HD subjects, occurring most likely at transcription, may underly their impaired immune function.

Recombinant interferon-gamma inhibits the growth of IL-6-dependent human multiple myeloma cell lines in vitro

Recombinant human IFN-gamma (100-1000 U/ml) inhibited the IL-6-induced growth of 2 human IL-6-dependent multiple myeloma (MM) cell lines U-1958 and U-266-1970 in vitro. In contrast, the U-1996 line, independent of IL-6 for maintenance at a slow growth rate but responding to IL-6 by increased proliferation, and the IL-6-independent U-266-1984 were refractory to the anti-proliferative effect of IFN-gamma. The effect of IFN-gamma in the sensitive MM cell lines was cytostatic in U-266-1970, and cytostatic and cytotoxic in U-1958. Northern blot analysis revealed that the growth inhibition of the IL-6-dependent MM cell line U-1958 was not due to down-regulation of IL-6 receptor mRNA expression and that the differential sensitivity to IFN-gamma was not due to differences in IFN-gamma receptor expression. The growth inhibition was not a consequence of an IFN-gamma-induced terminal differentiation as flow cytometric analyses demonstrated an arrest in all phases of the cell cycle. IFN-alpha inhibited the growth in 3 of the 4 cell lines tested. The results thus suggest that the particular MM phenotype, which includes IL-6 dependency for survival and growth, may also be characterized by IFN-gamma sensitivity. Furthermore, the study demonstrates that MM cell lines are not simultaneously sensitive to IFN-gamma and alpha, indicating that the mechanisms of action of the two types of IFN are distinct.

Pharmacokinetics and biological activity in subcutaneous long-term administration of recombinant interferon-gamma in cancer patients

We have investigated the pharmacokinetics, tolerance, and biological activity of recombinant human interferon-gamma (rHuIFN gamma) administered subcutaneously to cancer patients. Twenty-one patients with lymphoma and metastatic cancer received rHuIFN gamma (in doses of 0.1, 0.25, or 0.5 mg/m2) in two or three injections per week for up to 180 days. The most common adverse effects encountered were flu-like symptoms, fever and fatigue. The increase in body temperature after each administration ranged from 0 to 4 degrees C depending on the individual patient, but was unrelated to the rHuIFN gamma dose or its plasma concentration. The pharmacokinetic response of the patients after the two treatments showed a low intra-individual variability with respect to the plasma concentration/time profiles. However, as observed for the fever side-effect, the interindividual variation (CV greater than 50%) was high for the parameters area under the data points (AUC0-t) and maximum plasma concentration (cmax). Despite this high interindividual variability, the mean values obtained for AUC0-t and cmax after s.c. injection of rHuIFN gamma were approximately proportional to the dose administered: the injection of 0.1, 0.25 or 0.5 mg/m2 rHuIFN gamma resulted in AUC0-t values of 15.4, 31.5 or 69.6 ng h/ml, respectively and cmax was found to be 1.0, 2.4 and 4.9 ng/ml, respectively. With this s.c. administration protocol, objective antitumour responses were observed in two patients, but there was no partial or complete remission.

Transforming growth factor beta 1 enhances expression of 50 kDa protein related to 2'-5' oligoadenylate synthetase in human sperm cells

Human cellular polypeptide factors, namely interferon-alpha, interferon-gamma transforming growth factor (TGF)-alpha, and TGF-beta 1, were analyzed for their effect on motility of human sperm cells. Both interferons caused an inhibition of sperm cell motility due to direct cytotoxic effects without inducing 2'-5' oligoadenylate [2-5(A)]synthetase activity. TGF-alpha affected neither motility nor the levels of 2-5(A) synthetase in sperm cells. TGF-beta 1 had no affect on sperm motility, yet it caused an induction of 2-5(A)synthetase activity. Western immunoblot analysis of TGF-beta 1-treated sperm indicated an enhancement of a 50 kDa protein. Metabolic labeling of sperm cells revealed biosynthesis of one major protein of 50 kDa and at least five minor proteins in the range of 30-92 kDa; the level of 50 kDa protein increased after treatment with TGF-beta 1. The treatment of sperm cells with TGF-beta 1 did not affect their penetration in zona-free hamster eggs (SPA). These results indicate that TGF-beta 1 enhances expression of a 50 kDa protein related to 2-5(A) synthetase in human sperm cells along with other minor proteins, and this increase does not affect sperm motility and SPA.

Cytostasis of different tumours by a murine PPD-reactive CD4+ T lymphocyte clone is mediated by interferon-gamma and tumour necrosis factor alone or synergistically

We have shown that a murine CD4+ PPD-reactive T lymphocyte clone was weakly cytotoxic towards the syngeneic tumour B16 melanoma and MC6A fibrosarcoma which had been coated with PPD using a monoclonal antibody-PPD heteroconjugate. Cell-free supernatants produced by PPD-stimulated T lymphocyte clones were however highly cytostatic for the two tumour targets when assayed over 48-72 h. In this study we have demonstrated good titres of tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma) in the supernatants, which accounted for their observed cytostatic activity on the tumour targets. The high level of cytostasis seen with the B16 melanoma using the supernatants could be attributed to their sensitivity to the cytostatic activity of IFN-gamma; the lower levels of cytostasis seen with the IFN-gamma-resistant MC6A target was the result of IFN-gamma increasing the sensitivity of this target to TNF. Antibodies to IFN-gamma were able to neutralize the majority of the cytostatic activity of the supernatants on both targets, consistent with the role demonstrated for this lymphokine.