Showing papers on "Interferon published in 1987"

Interferon beta 2/B-cell stimulatory factor type 2 shares identity with monocyte-derived hepatocyte-stimulating factor and regulates the major acute phase protein response in liver cells

Abstract: One of the oldest and most preserved of the homeostatic responses of the body to injury is the acute phase protein response associated with inflammation. The liver responds to hormone-like mediators by the increased synthesis of a series of plasma proteins called acute phase reactants. In these studies, we examined the relationship of hepatocyte-stimulating factor derived from peripheral blood monocytes to interferon beta 2 (IFN-beta 2), which has been cloned. Antibodies raised against fibroblast-derived IFN-beta having neutralizing activity against both IFN-beta 1 and -beta 2 inhibited the major hepatocyte-stimulating activity derived from monocytes. Fibroblast-derived mediator elicited the identical stimulated response in human HepG2 cells and primary rat hepatocytes as the monocyte cytokine. Finally, recombinant-derived human B-cell stimulatory factor type 2 (IFN-beta 2) from Escherichia coli induced the synthesis of all major acute phase proteins studied in human hepatoma HepG2 and primary rat hepatocyte cultures. These data demonstrate that monocyte-derived hepatocyte-stimulating factor and IFN-beta 2 share immunological and functional identity and that IFN-beta 2, also known as B-cell stimulatory factor and hybridoma plasmacytoma growth factor, has the hepatocyte as a major physiologic target and thereby is essential in controlling the hepatic acute phase response.

Treatment of multiple sclerosis with gamma interferon Exacerbations associated with activation of the immune system

Abstract: We treated 18 clinically definite relapsing-remitting MS patients with recombinant gamma interferon in a pilot study designed to evaluate toxicity and dosage. Patients received low (1 microgram), intermediate (30 micrograms), or high (1,000 micrograms) doses of interferon by intravenous infusion twice a week for 4 weeks. Serum levels of gamma interferon were proportional to dose and no interferon was detected in CSF. Seven of the 18 patients had exacerbations during treatment, a significant increase compared with the prestudy exacerbation rate (p less than 0.01). Exacerbations occurred in all three dosage groups and were not precipitated by fever or other dose-dependent side effects. There were significant increases in circulating monocytes bearing class II (HLA-DR) surface antigen, in the proliferative responses of peripheral blood leukocytes, and in natural killer cell activity. These results show that systemic administration of gamma interferon has pronounced effects on cellular immunity in MS and on disease activity within the CNS, suggesting that the attacks induced during treatment were immunologically mediated. Gamma interferon is unsuitable for use as a therapeutic agent in MS. Agents that specifically inhibit gamma interferon production or counteract its effects on immune cells should be investigated as candidates for experimental therapy.

Immunoregulatory activity of recombinant human tumor necrosis factor (TNF)-alpha: induction of TNF receptors on human T cells and TNF-alpha-mediated enhancement of T cell responses

Abstract: The expression of specific tumor necrosis factor (TNF) membrane receptors and biological effects of recombinant TNF (rTNF)-alpha on normal human T lymphocytes were studied. Although resting T cells lacked specific binding capacity for rTNF-alpha, high affinity (Kd 70 pM) TNF receptors were de novo induced upon primary activation of T cells. Comparison of TNF receptor expression with that of high affinity interleukin 2 (IL-2) and interferon-gamma (IFN-gamma) receptors, respectively, revealed similarities to IL 2-receptor expression with respect to kinetics of induction. However, maximum expression of TNF receptors (approximately equal to 5000/cell at day 6) and subsequent decline occurred approximately 3 days after the peak of IL 2-receptor expression. In contrast, no change in the expression of IFN-gamma receptors (Kd 10 pM, 300 to 400 receptors/cell) was found in the course of T cell activation. On activated TNF receptor positive T cells, TNF-alpha exerted multiple stimulatory activities. Thus TNF increased the expression of HLA-DR antigens and high affinity IL 2 receptors. As a consequence, TNF-treated T cells showed an enhanced proliferative response to IL 2. Moreover, TNF-alpha was effective as a co-stimulator of IL 2-dependent IFN-gamma production. These data indicate that TNF-alpha may regulate growth and functional activities of normal T cells.

Recombinant interleukin-2 directly augments the cytotoxicity of human monocytes.

Abstract: Interleukin-2 (IL-2), originally described as a growth factor required for sustained proliferation of T cells in vitro1,2 is a glycoprotein hormone of known structure3 which appears to be important for the generation of immune responses in vivo4. As well as T lymphocytes, B lymphocytes5 and large granular lymphocytes with natural killer activity (NK cells)6 can also respond to IL-2. The action of IL-2 seemed to be limited specifically to lymphocytes, however, and the term 'T-lymphocytotrophic hormone' was used7. Here we provide evidence that human monocytes display a substantially increased cytotoxic activity as a direct and rapid response to human recombinant IL-2 but not to human recombinant glycosylated interferon-γ (IFN-γ) or lipopolysac-charide. Our results reveal a previously unknown function of IL-2 and suggest its possible involvement in monocyte-T cell interactions.

Constitutive expression of (2'-5') oligo A synthetase confers resistance to picornavirus infection.

Abstract: Study of the mechanisms by which interferon (IFN) treatment of cells induces resistance to virus infections has been complicated by the multiple biochemical changes induced. Over 20 proteins are increased by IFN, including the double-stranded (ds) RNA-activated protein kinase, (2'-5') oligo A synthetase, surface proteins such as the major histocompatibility complex (MHC) proteins, and various proteins with unknown functions. The availability of cloned complementary DNAs for several IFN-induced proteins now allows us to probe their roles in IFN action. For instance, the murine Mx protein has been shown to confer resistance, to influenza virus. We studied chinese hamster ovary (CHO) cell clones expressing high constitutive levels of (2'-5') A synthetase as a result of transfection with the cDNA encoding the enzyme form which has a relative molecular mass (Mr) of 40K. Elevated enzyme correlates directly with resistance to infection by a picornavirus such as Mengo, but does not make the cells resistant to vesicular stomatitis virus (VSV).

Quantitation, Specificity, Distribution, and Regulation of Their Expression

Abstract: Several factors are involved in the regulation of growth and differentiation of B cells (reviewed in 1) . In fact, B cell stimulatory factor 2 (BSF-2),' which has recently been cloned (2), is a distinct cytokine of 21 kD that acts on activated normal human B cells as well as EBV-transformed B-lymphoblastoid cell lines to induce immunoglobulin secretion (3, 4) . The study with the antipeptide antibody specific to BSF-2 demonstrated that several tumor cells, including cardiac myxomas, produce BSF-2, and patients with such tumors show hypergammaglobulinemia and autoantibody production (5) . From these earlier investigations it was suggested that BSF-2 has an important role in the regulation of antibody production . Recent reports have indicated identity between BSF-2 and other cytokines known as interferon 02 (IFN -N2) and hybridoma plasmacytoma growth factor (HPGF) (6, 7) . Another identical molecule is also reported as a 26 kD protein (8) that is expressed in human fibroblast by poly (IC) in the presence of cycloheximide (9) or (IL-1) (10) . These facts suggest that BSF-2 has an important role not only in the immunoglobulin production of B cells but also in the regulation of growth and differentiation of several other types of cells . The recombinant BSF-2 had no detectable antiviral activity2 (11), and it has been proposed that it be called IL-6 (11) . However, no information is available as to the presence of specific BSF-2 receptors (BSF-2-R) mediating the physiological effects . The availability of highly purified BSF-2 produced in Escherichia coli by recombinant DNA techniques enabled us to study the presence and the properties ofBSF-2-R . We report here in this study the number and distribution of BSF-2-R . Our findings indicate that BSF-2-R are widely distributed in several tissues and cell lines . In contrast to BSF-1-R, which are found on resting B cells (12), our observations indicate that normal B cells express BSF-2-R only after activation . 'Abbreviations used in this paper:

Trans-activation of human immunodeficiency virus gene expression is mediated by nuclear events

Abstract: Human immunodeficiency virus encodes a gene product termed tat that is able to activate viral gene expression when present in trans. The mechanism of action of the tat gene product appears to be bimodal, resulting in both an increase in the steady-state level of viral mRNA and the enhanced translation of that RNA. In this report we have examined the mechanism by which tat elevates viral mRNA levels. Data are presented demonstrating that tat acts by increasing the rate of viral transcription, rather than by modulating the stability of viral mRNA. Indirect immunofluorescence was used to show that tat is predominantly localized in the nucleus of expressing cells, a location consistent with a role in the regulation of viral transcription. These results suggest that tat could play a role in human immunodeficiency virus replication essentially similar to that proposed for the trans-acting nuclear gene products described for several other virus species.

Synergistic inhibition of human immunodeficiency virus in vitro by azidothymidine and recombinant alpha A interferon.

Abstract: Both recombinant alpha A interferon and azidothymidine inhibit the replication of human immunodeficiency virus in peripheral blood mononuclear cells. Combinations of recombinant alpha A interferon and azidothymidine at concentrations that are easily achievable in patients synergistically inhibit human immunodeficiency virus in vitro with minimal toxicity. Combinations of antiretroviral compounds that act by different mechanisms may prove useful in the treatment of acquired immunodeficiency syndrome-related disorders.

Lymphokines and interferons : a practical approach

Abstract: Induction, production and purification of natural mouse IFN-a and b Induction, production and purification of murine gamma interferon Production and purification of recombinant mouse interferon -y from E.Coli Production of human interferon -a Production of recombinant interferons by expression in heterologous mammalian cells Biological assays for interferons Quantitation of IFN mRNA Antibodies against interferons: characterization of interferos and immunoassays Quantification of interferons by anti-viral assays and their standardization Analysis of anti-viral mechanisms: interferon-regulated 2'5' oligoadenylate and protein kinase systems Cell growth inhibition by interferons and tumour necrosis factor Cytoxicity assays for tumour necrosis factor and lymphotoxin Anti-microbial and hydrogen peroxide assays for mafs In vitro tumour cytotoxicity assays for macrophage activation Measurement of interleukin-1 activity Production and assay of interleukin 2 Assays for interleukin 3 and other myeloid colony-stimulating factors Eosinophil differentiation factor and its associated B cell growth factor activities Assays for human B cell growth and differentiation factors

Induction of colony stimulating factor in vivo by recombinant interleukin 1 alpha and recombinant tumor necrosis factor alpha 1.

Abstract: In response to a potent inflammatory challenge, such as Gram-negative endotoxin, a number of cytokines are induced that, in turn, mediate many of the pathophysiologic alterations associated with endotoxicity. In this study, we have observed two endotoxin-associated monokines, recombinant interleukin-1 alpha (rIL 1 alpha) and recombinant tumor necrosis factor alpha (rTNF alpha), to induce colony stimulating factor (CSF) in vivo. The CSF activities produced in response to rIL 1 alpha or rTNF alpha gave rise to a mixture of granulocyte-macrophage colonies and were induced in a dose- and time-dependent fashion, peaking within 3 hr of cytokine injection (preceding peak CSF induction by endotoxin by several hours). Combined injection of suboptimal concentrations of rIL 1 alpha and rTNF alpha were additive, and simultaneous injection of optimal concentrations of each failed to increase CSF levels over that observed with either cytokine alone. Unlike endotoxin, neither cytokine induced interferon in vivo. These findings extend our understanding of the cytokine cascade that is operative in an inflammatory response and may account for many of the observed hematopoietic alterations that accompany inflammation.

Human chromosomes 6 and 21 are required for sensitivity to human interferon. gamma

Abstract: The human interferon gamma receptor has previously been assigned to chromosome 6. Chromosome 6 also encodes HLA, the human class I major histocompatibility antigens. However, the presence of chromosome 6 in hamster-human hybrids is by itself insufficient to confer sensitivity to human immune interferon as measured by the induction of human HLA. Human chromosome 21 was found to be the second chromosome essential for HLA inducibility. Similar results were found with mouse-human somatic cell hybrids. Thus, at least two steps are involved in the action of human interferon gamma: the binding of interferon gamma to its receptor coded by chromosome 6 and the linkage of this binding event through a factor coded by chromosome 21 to trigger biological action. Both of these steps are species-specific.

The role of interferon-beta 1 and the 26-kDa protein (interferon-beta 2) as mediators of the antiviral effect of interleukin 1 and tumor necrosis factor.

Abstract: This study confirms our earlier finding that human interleukin (IL)-1 beta exerts an antiviral effect on diploid fibroblasts and on MG-63 osteosarcoma cells. It also extends the observation in that a similar effect was noted on aged but not freshly trypsinized HEp-2 cells, and that not only IL-1 beta but also IL-1 alpha and tumor necrosis factor (TNF)-alpha exerted similar antiviral effects on cells. The antiviral effects of these cytokines were neutralized by addition to the assay system of an antibody that was specific for interferon (IFN)-beta 1, indicating that IFN-beta 1 or a structurally or functionally related substance is involved in the antiviral activity observed. Both IL-1 and TNF were able to induce production of the 26-kDa protein, also known as IFN-beta 2, hybridoma/plasmacytoma growth factor (HPGF) or B-cell stimulatory factor-2 (BSF-2) and previously proposed as an alternative to IFN-beta 1 for mediating the antiviral effect of TNF. However, no good correlation was found between the antiviral effects of TNF and its potential to induce production of the 26-kDa protein. Furthermore, the anti-IFN-beta 1 serum which neutralized the antiviral activity of IL-1 and TNF did not cross-react with the 26-kDa protein. Conversely, the antiviral effect of IL-1 and TNF was only weakly neutralized by an antibody that did react with the 26-kDa protein and showed low cross-reactivity with IFN-beta 1. These observations, together with the low specific activity of the 26-kDa protein as an antiviral agent (less than 10(5) U/mg protein) provide strong arguments against this protein and in favor of IFN-beta 1 (or still another IFN-beta 1-related molecule) as the ultimate mediator of the antiviral effect of IL-1 and TNF.

Interferon treatment of renal cell carcinoma. Current status and future prospects.

Abstract: Studies with various interferon alpha preparations, including interferons induced in human leukocytes, interferon alfa-N1, interferon alfa-2a, and interferon alfa-2b, have all provided evidence for modest but reproducible antitumor activity in advanced renal cell carcinoma. Review of the data suggests that maximal response rates are achieved when interferon alpha is administered within a fairly restricted range of moderate to high doses, whereas extremely low or extremely high dosage regimens appear less likely to induce therapeutic response. Preliminary evidence suggests that interferons beta and gamma may also induce regression of metastatic renal cell carcinoma. Recent in vitro and animal studies have shown that combinations of interferon gamma with interferon alpha or interferon beta, produce synergistic biologic activities, suggesting that the various interferons may have different pathways of action related to agent-specific cellular receptors. Possible interactions of different interferon species given concurrently to patients with renal cell carcinoma are under investigation, as are combinations of interferon alpha with chemotherapeutic agents. Despite in vitro data suggesting enhanced antiproliferative activity for the combination of interferon alpha and vinblastine, most clinical studies of this combination have proved to be no more effective than interferon alpha alone, but they have provided evidence of increased toxicity. The recent identification and purification of other biologically active cytokines, such as tumor necrosis factor and interleukin-2, and of monoclonal antibodies that recognize unique cell surface antigens on renal carcinoma cells, provide exciting possibilities for combination regimens with various interferon species.

Murine natural killer cells limit coxsackievirus B3 replication.

Abstract: Previous indirect evidence suggested that natural killer (NK) cells play a role in coxsackie virus B3 serotype 3, myocarditic variant (CVB3m)-induced myocarditis by limiting virus replication. In this study, we present direct evidence that NK cells can limit CVB3m replication both in vitro and in vivo. Virus titers are lowered in primary murine neonatal skin fibroblast (MNSF) cultures incubated with activated splenic large granular lymphocytes (LGL) taken from mice 3 days postinoculation of CVB3m, a time of maximal NK cell activity. The antiviral effect of this cell population is diminished by complement-mediated lysis with the use of anti-asialo GM1 antiserum but not with anti-Lyt-2 monoclonal antibody. Neither interferon nor anti-CVB3m-neutralizing antibody was detected in these cultures. Although activated LGL initiate lysis within CVB3m-infected MNSF in vitro within 3 hr of addition, they do not lyse uninfected MNSF cultures. CVB3m replication is required for expression of surface changes on MNSF that result in lysis by NK cells because cell cultures treated with compounds that prevent CVB3m replication are not killed by LGL. LGL also do not lyse MNSF cultures inoculated with UV-inactivated virus. Mice inoculated with activated LGL and subsequently challenged with CVB3m had reduced titers of virus in heart tissues in comparison to titers of CVB3m in heart tissues of mice not given LGL. The antiviral activity of the LGL preparation was abolished by prior treatment with anti-asialo GM1 antiserum plus complement but not by prior treatment with anti-Lyt-2 monoclonal antibody and complement. These data suggest that NK cells can specifically limit a nonenveloped virus infection by killing virus-infected cells.

Activity of Interferons Alpha, Beta, and Gamma Against Human Immunodeficiency Virus Replication In Vitro

Abstract: The antiviral activities of various interferon preparations against human immunodeficiency virus (HIV) were evaluated in vitro. Recombinant inferferon alpha-A, and beta interferons and leukocyte-derived alpha interferons show similar concentration-dependent antiviral activity. Recombinant and lymphocyte-derived gamma interferons show minimal antiviral activity against HIV replication in normal peripheral blood mononuclear cells, but definite activity against HIV in the H9 lymphocytic and U937 monocyte-macrophage cell lines.

Functional equivalents of interferon-mediated signals needed for induction of an mRNA can be generated by double-stranded RNA and growth factors.

Abstract: In our earlier studies we demonstrated that in HeLaM cells, interferon-alpha produces two functionally distinguishable signals, both of which are needed for induced transcription of mRNA 561 and other inducible mRNAs. Interferon-gamma cannot induce mRNA 561 because it produces only signal 1. Here we report that platelet-derived growth factor or epidermal growth factor could also produce signal 1. On the other hand, signal 2, which can be produced by interferon-alpha but not by interferon-gamma, could be elicited also by double-stranded RNA. Several lines of evidence suggest that the production of signal 2 by double-stranded RNA was not mediated through interferon. Interferon-induced transcription of mRNA 561 in HeLaM cells or in human fibroblast GM2767 cells was transient. However, in interferon-alpha-treated GM2767 cells, which had ceased to synthesize mRNA 561, transcription of this mRNA could be induced effectively by double-stranded RNA suggesting that this induction process could bypass the interferon-mediated down-regulation of induced transcription. Unlike HeLaM and GM2767 cells, in Daudi cells, induction of mRNA 561 by interferon-alpha was not transient. Transcription of this and two other induced mRNAs continued at a high rate even after 18 h of interferon-alpha treatment of these cells. The lack of down-regulation of interferon-induced gene expression may be responsible for interferon's acute antigrowth effects on these cells.

Rapid enhancement of beta 2-interferon/B-cell differentiation factor BSF-2 gene expression in human fibroblasts by diacylglycerols and the calcium ionophore A23187

Abstract: The expression in human fibroblasts of the beta 2-interferon (IFN-beta 2) gene, which is now recognized to be identical to the gene encoding B-cell differentiation factor BSF-2, is enhanced by several cytokines that affect cell growth (tumor necrosis factor, interleukin 1, platelet-derived growth factor, and beta 1-interferon). We have examined the possibility that IFN-beta 2 gene expression is regulated through activation, by diacylglycerol, of the protein kinase C pathway. The synthetic diacylglycerols 1,2-dioctanoylglycerol (diC8) and 1-oleoyl-2-acetylglycerol strongly enhanced IFN-beta 2, but not IFN-beta 1, gene expression in human fibroblasts (FS-4 strain). An increase in IFN-beta 2 mRNA level was detected within 15 min after addition of diC8 (290 microM) to FS-4 cells and was maximal approximately 20 hr later. An increase in IFN-beta 2 gene transcription was detected within 5 min of addition of diC8, and the rate of transcription was near-maximal by 15-30 min. The enhancement of IFN-beta 2 gene expression by diC8, interleukin 1, or tumor necrosis factor was not prevented by H8, a preferential inhibitor of cAMP- and cGMP-dependent protein kinases, but was blocked by H7, an inhibitor of protein kinase C as well as of cyclic nucleotide-dependent protein kinases. diC8 was found to protect FS-4 cells from the cytopathic effect of vesicular stomatitis virus; this protection was blocked by polyclonal or monoclonal antibodies that neutralize IFN-beta, suggesting that the antiviral effect was due to the secretion of IFN-beta 2 by the diC8-treated fibroblasts. The calcium ionophore A23187 (1-10 microM) also elicited an increase in the level of IFN-beta 2 mRNA in FS-4 fibroblasts; appropriate combinations of A23187 and diC8 had at least an additive effect in enhancing IFN-beta 2 mRNA levels. These results show that protein kinase C-activating or [Ca2+]-elevating agents rapidly increase the expression of the IFN-beta 2 gene in human fibroblasts.

Identification of interferon-modulated proliferation-related cDNA sequences

Abstract: To identify genes mediating the antiproliferative action of interferon (IFN), two cDNA libraries were constructed with mRNA from IFN-treated and untreated human fibrosarcoma (HT1080) cells previously shown to be highly sensitive to the antiproliferative effects of IFN. Differential screening of these two libraries identified cloned sequences whose expression was either induced or repressed with IFN treatment. Rescreening of these sequences with cDNA probes constructed from proliferating or quiescent cells led to the identification of one IFN-induced and three IFN-repressed sequences whose expressions also appeared to be modulated by cell proliferation. Blot-hybridization analysis revealed that RNA levels corresponding to the three repressed genes decreased when HT1080 cells were treated with IFN or when proliferation of normal CUA foreskin fibroblast cells became naturally arrested by contact inhibition. Levels of RNA corresponding to the induced gene increased in HT1080 cells within 24 hr after IFN-treatment but declined below basal levels by 48 hr. Expression of these genes was unaffected or only slightly affected by IFN treatment in variant cells resistant to the antiproliferative effects of IFN. Collectively, these results suggest that the identified cDNAs correspond to genes that are involved in the antiproliferative action of IFN. Moreover, these results also suggest that IFN's antiproliferative action may be exerted through genes that contribute to arresting cell proliferation during contact inhibition.

Incidence and clinical significance of neutralizing antibodies in patients receiving recombinant interferon alfa-2a by intramuscular injection.

Abstract: More than 1600 patients with neoplastic disorders have received recombinant human interferon alfa-2a (Roferon®-A, Hoffmann-La Roche, Nutley, NJ) as part of ongoing or completed clinical trials. In this report, the efficacy of interferon alfa-2a therapy was compared with the incidence of antibodies to this interferon in 617 patients who received the drug by intramuscular administration. Antibody measurements were performed using a highly sensitive enzyme immunoassay, and an interferon antiviral neutralization bioassay. Partial or complete remission occurred in 28% (43 of 152) of the antibody-positive patients, and in 24% (112 of 465) of the antibody-negative patients (P = 0.33). The highest incidence of antibody formation occurred among patients with renal cell carcinoma and acquired immune deficiency syndrome (AIDS)-related Kaposi's sarcoma (44% and 34%, respectively). Both the duration of treatment and length of survival were significantly longer for antibody-positive than for antibody-negative patients. No significant intergroup differences emerged for response rates or for time to onset or duration of therapeutic response. When results from the above assays were compared to those used for the detection of antibodies to recombinant interferon alfa-2b (Intron A®, Schering-Plough Inc., Kenilworth, NJ), the immunoradiometric assay method was determined to be seriously deficient for determination of antibody incidence. This decreased assay sensitivity may account for the reportedly lower incidence of antibodies to recombinant alfa-2b interferon.

Protective mechanisms against pulmonary infection with influenza virus. I. Relative contribution of polymorphonuclear leukocytes and of alveolar macrophages to protection during the early phase of intranasal infection.

Abstract: Summary The relative contribution of polymorphonuclear leukocytes and macrophages in the early protection against intranasal infection of mice with influenza virus was investigated. Virus multiplication in the lung in the early phase of infection with less than 1.5 × 103 plaque-forming units was enhanced by X-ray irradiation. The intranasal administration of carrageenan did not influence the titre of virus. However, when mice were infected with 1.5 × 104 plaque-forming units, the virus titre was elevated by intranasal administration of carrageenan as well as by X-ray irradiation, but not by intraperitoneal administration of carrageenan. The intranasal administration of carrageenan not only inhibited the phagocytic activity of alveolar macrophages but also enhanced susceptibility to the virus. On the other hand, polymorphonuclear leukocytes were capable of phagocytosing the virus in vitro and were non-permissive for virus infection. Neutralizing antibody and interferon were not detectable in the early stage of the infection. These results suggested that polymorphonuclear leukocytes (X-ray-sensitive, carrageenan-resistant) were the cells primarily responsible for early protection in influenza virus infection and that after infection with a high dose of the virus alveolar macrophages (X-ray-resistant, carrageenan-sensitive) also played a protective role in the early phase.

Interferons increase transcription of a major histocompatibility class I gene via a 5' interferon consensus sequence.

Abstract: Interferons (IFNs) augment expression of major histocompatibility class I genes in many cells. To study the effect of IFNs on transcription of class I genes, we prepared and tested activity of chloramphenicol acetyltransferase (CAT) hybrid genes in which the cat gene is under the control of the 5' flanking region of the murine H-2Ld gene. NIH 3T3 cells transiently transfected with a cat construct having the sequence from position -210 to -134 showed a four- to fivefold increase in CAT activity when treated with IFN-alpha/beta. This sequence contains the IFN consensus sequence (ICS) shared among IFN-inducible genes, as well as the class I regulatory element (CRE) that controls up and down regulation of class I gene expression. To determine the precise sequence requirement for the IFN action, the ICS and CRE were independently placed upstream of the class I or a heterologous simian virus 40 promoter, and CAT activity was tested. The ICS, but not the CRE, enhanced activity of both promoters by about twofold upon exposure to IFN-alpha/beta, although greater responses were noted when the ICS and CRE were combined. These results demonstrate that the ICS alone is capable of enhancing promoter activity in response to IFN-alpha/beta treatment and that the CRE exerts a synergistic effect. Further, we show that the ICS functions as an inducible enhancer since it acts regardless of its orientation and distance in the simian virus 40 promoter.

Interferon-inducible gene maps to a chromosomal band associated with a (4;11) translocation in acute leukemia cells.

Abstract: An interferon-inducible cytokine, IP-10, containing homology to a family of proteins having chemotactic (platelet factor 4, beta-thromboglobulin) and mitogenic (connective tissue-activating peptide III) activities has been mapped to chromosome 4 at band q21, a locus associated with an acute monocytic/B-lymphocyte lineage leukemia that exhibits the nonrandom translocation t(4;11)(q21;q23). In situ hybridization of t(4;11)(q21;q23)-carrying leukemic cells revealed that the IP-10 gene is proximal to the breakpoint of this translocation. No DNA rearrangement was evident when the IP-10 gene was hybridized to genomic DNA isolated from two patients' leukemic cells that contain t(4;11)(q21;q23). However, restriction fragment length polymorphism in the 5' region of the IP-10 gene was detected. The ETS1 protooncogene is located at 11q23 and is known to translocate to chromosome 4 in t(4;11) (q21;q23) and into the interferon gene cluster in (9;11) (p22;q23). Both translocations are associated with acute monocytic leukemia. These results suggest a model in which juxtaposition of genetic loci regulated by antiproliferative signals, such as interferon, next to an oncogene, like ETS1, could effectively short circuit homeostatic control circuits and contribute to the neoplastic state.

Virus-resistant transgenic mice

Abstract: A transgenic mouse with enhanced viral resistance transmissible to its offspring is prepared by introduction of a gene encoding a human interferon having antiviral activity into a host mouse. The gene encodes the interferon of a different animal species and therefore its expression product is less toxic to the host at an embryonic, fetal, neonatal or junvenile stage of development. Preferably, the human beta interferon gene is introduced into the cells of a mouse.