Showing papers on "Interferon published in 1983"

Production of human beta interferon in insect cells infected with a baculovirus expression vector.

Abstract: Autographa californica nuclear polyhedrosis virus (AcNPV) was used as an expression vector for human beta interferon. By using specially constructed plasmids, the protein-coding sequences for interferon were linked to the AcNPV promoter for the gene encoding for polyhedrin, the major occlusion protein. The interferon gene was inserted at various locations relative to the AcNPV polyhedrin transcriptional and translational signals, and the interferon-polyhedrin hybrid genes were transferred to infectious AcNPV expression vectors. Biologically active interferon was produced, and greater than 95% was secreted from infected insect cells. A maximum of ca. 5 X 10(6) U of interferon activity was produced by 10(6) infected cells. These results demonstrate that AcNPV should be suitable for use as a eucaryotic expression vector for the production of products from cloned genes.

Ia expression by vascular endothelium is inducible by activated T cells and by human gamma interferon.

Abstract: We have used monoclonal antibody binding, measured by radioimmunoassay, fluorescence flow cytometry, and ultrastructural immunocytochemistry, to measure expression of Ia antigens on cultured human umbilical vein endothelial (HUVE) cells. Under standard culture conditions, HUVE cells do not express Ia antigens. However, treatment of primary HUVE cultures with phytohemagglutinin induces the expression of Ia antigens. Every endothelial cell in the culture becomes Ia-positive and endothelial cells appear to synthesize Ia. HLA-A,B is concomitantly increased. The expression of Ia appears to be mediated by T cells because (a) pretreatment of primary HUVE cultures with OKT3 plus complement blocks the action of the lectins but not of medium conditioned by lectin-activated peripheral blood mononuclear cells; (b) co-culture of endothelial cells with allogeneic T cells, in the absence of lectin, also induces endothelial Ia; and (c) human immune (gamma) interferon, produced by Chinese hamster ovary cells transfected with the human gamma interferon gene, directly induces endothelial Ia. During co-culture with lymphocytes, about one-third of the endothelial cells are Ia-positive after 24 h and all of the endothelial cells are Ia-positive by 72 h. Proliferation of allogeneic T cells starts by 96 h and peaks at 144 h. Thus, endothelial Ia appears sufficiently early to be a determinant for the proliferation of allogeneic T cells. Inducible expression of Ia by endothelium may be important both for allograft rejection and for recruitment of circulating T cells into the site of an immune response.

Human tumor necrosis factor produced by human B-cell lines: synergistic cytotoxic interaction with human interferon

Abstract: Human cell lines of hematopoietic origin were tested for production of tumor necrosis factor (TNF). B-cell lines transformed by Epstein-Barr virus release a factor (referred to as hTNF) that is cytotoxic for mouse L cells sensitive to mouse TNF but not for L cells resistant to mouse TNF. Exposure to 4 beta-phorbol 12 beta-myristate 13 alpha-acetate augmented production of hTNF. hTNF activity was not found in supernatants of cell lines of T-cell, monocytic, or promyelocytic origin. Partially purified hTNF has a molecular weight of approximately 70,000, has no interferon activity, is acid labile, is destroyed by heating at 70 degrees C for 1 hr, induces cross-resistance to mouse TNF in vitro, and causes hemorrhagic necrosis of Meth A mouse sarcoma in the standard in vivo mouse TNF assay. Tests with a panel of 23 human cancer cell lines showed that hTNF is cytotoxic for 7 cell lines, cytostatic for 5, and has no effect on 11. Comparative studies with human alpha, beta, and gamma interferons indicated that sensitivity to hTNF and interferon can be distinguished. Combined treatment with hTNF and alpha or gamma interferon resulted in a synergistic cytotoxic effect.

Interleukin 2-mediated immune interferon (IFN-gamma) production by human T cells and T cell subsets.

Abstract: Human interleukin 2 (IL 2, or T cell growth factor), which was free of lectin and interferon activity (IFN), induced human peripheral T lymphocytes to produce immune IFN (IFN-gamma). In contrast, non-T cells and macrophages did not produce IFN-gamma in response to IL 2. IL 2 acted directly on unstimulated T cells to induce IFN-gamma production, and also acted in synergy with a suboptimal dose (2 micrograms/ml) of concanavalin A (Con A) to enhance IFN-gamma production. The IFN-gamma-inducing activity of partially purified IL 2 was absorbed along with the IL 2 activity by murine IL 2-dependent CT-6 cell line cells. This further supports the view that IFN-gamma-inducing activity is identical to IL 2. When T cells were separated further into helper/inducer T4+ and suppressor/cytotoxic T8+ subsets by negative selection with monoclonal antibody and complement, both T4+ and T8+-enriched cells produced significant levels of IFN-gamma in response to IL 2. Complete removal of macrophages from purified T lymphocyte populations by treatment of OKM1 plus complement consistently reduced IFN-gamma production in response to IL 2 to a limited degree; readdition of macrophages restored IFN-gamma production by both T cell subsets. This observation that IL 2 contributes to the production of IFN-gamma by human lymphocytes suggests that a cascade of lymphocyte-cell interactions participates in human immune responses.

Recombinant immune interferon increases immunoglobulin G Fc receptors on cultured human mononuclear phagocytes.

Abstract: Although recent studies suggest that interferons can increase the number of IgG Fc receptor (FcR gamma) sites on mouse macrophages, direct assessment of similar effects on human mononuclear phagocytes is lacking. We therefore measured the specific binding of 125I- and fluorescein-labeled IgG1 to human monocytes and leukemic cell lines after culture in vitro with highly purified human interferons. We report that natural and recombinant human gamma-interferon causes a dramatic (nearly 10-fold) increase in the number of FcR gamma on normal human monocytes and on the human cell lines HL-60 and U-937. Alpha and beta-interferons cause a modest but significant increase in these receptors. This report demonstrates that gamma-interferon acts directly on human mononuclear phagocytes to increase FcR gamma sites, it identifies a qualitative difference in the physiologic actions of human type I and type II interferons, and it suggests that HL-60 and U-937 cells will be important models for further study of the molecular mechanisms of interferon action. The results reported here could also be the basis for a bioassay to assess the pharmacokinetics and variability of gamma-interferon action on monocytes of individual patients during treatment in vitro and in vivo.

Natural killer cell depletion enhances virus synthesis and virus-induced hepatitis in vivo.

Abstract: The role of natural killer (NK) cells in the natural resistance of mice to infections by several viruses was examined. Mice were specifically depleted of NK cells by i.v. injection of rabbit antiserum to asialo GM1, a neutral glycosphingolipid present at high concentrations on the surface of NK cells. Control mice were left untreated or were injected with normal rabbit serum. Four to 6 hr later, these mice were infected with lymphocytic choriomeningitis virus (LCMV), mouse hepatitis virus (MHV), murine cytomegalovirus (MCMV), or vaccinia virus. The mice were sacrificed 3 days post-infection and assayed for virus in liver and spleen, spleen NK cell activity, and plasma interferon (IFN). All mice treated with anti-asialo GM1 antibody had drastically reduced NK cell-mediated lysis. Correlating with NK cell depletion, these mice had significantly higher (up to 500-fold) titers of MCMV, MHV, or vaccinia virus in their livers and spleens as compared to control mice. NK cell-depleted MCMV and MHV-infected mice had higher levels of plasma IFN than controls, correlating with the higher virus titers. These NK cell-depleted, virus-infected mice had more extensive hepatitis, assayed by the number of inflammatory foci in their livers, as compared to control virus-infected mice; these foci were also larger and contained more degenerating liver cells than those in control mice. In contrast to the results obtained with MHV, MCMV, and vaccinia virus, NK cell depletion had no effect on virus titers in the early stages of acute LCMV infection or during persistent LCMV infection. Mice depleted of NK cells had similar amounts of LCMV in their spleens and similar plasma IFN levels. Because this antibody to asialo GM1 does not impair other detectable immunologic mechanisms, these data support the hypothesis that NK cells act as a natural resistance mechanism to a number of virus infections, but suggest that their relative importance may vary from virus to virus.

Comparative analysis of the influences of human gamma, alpha and beta interferons on human multipotential (CFU-GEMM), erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells.

Abstract: Preparations of human interferon (HuIFN) immune (gamma) (2 X 10(7) units/mg protein), HuIFN leukocyte (alpha) (1.4 X 10(8) units/mg protein) and HuIFN fibroblasts (beta) (10(6) U/mg protein) were assessed for their influence on colony formation of human hematopoietic progenitor cells: colony forming unit-granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM), burst forming unit-erythroid (BFU-E), day 7 colony forming unit granulocyte-macrophage (CFU-GM) and day 14 CFU-GM. Colony formation by CFU-GEMM and BFU-E was suppressed equally by the three preparations of HuIFN, but colony formation by CFU-GM was suppressed differentially. CFU-GM were, on the whole, more responsive to HuIFN gamma than HuIFN alpha, and HuIFN beta was least effective. HuIFN alpha, but not HuIFN gamma or HuIFN beta, suppressed colony formation from CFU-GM without also suppressing the total number of colonies plus clusters. This was due to an increase in the numbers of clusters formed in the presence of HuIFN alpha. The suppressive influence on colonies from CFU-GM by the preparations of HuIFN and the enhancement of clusters by HuIFN alpha was apparently equal for colonies and clusters of neutrophils, eosinophils, macrophages and neutrophils plus macrophages. The suppressive effects of HuIFN gamma were inactivated by a monoclonal antibody to HuIFN gamma and the suppressive and enhancing effects of HuIFN alpha were inactivated with a heteroantiserum to HuIFN alpha. Depletion of monocytes, T lymphocytes and B lymphocytes from the target bone marrow cells had no influence on the effects of the preparations of HuIFN. These results demonstrate that the effects of HuIFN gamma and HuIFN alpha are due to the HuIFN themselves and that these actions on the hematopoietic progenitor cells are probably not mediated through monocytes and/or lymphocytes.

Renal cell carcinoma: antitumor effects of leukocyte interferon.

Abstract: Partially purified human leukocyte (α) interferon was administered i.m. at a dose of 3 × 10 6 units/day to 19 patients with metastatic renal cell carcinoma. Five patients (26%) showed partial responses; two patients (10.5%), objective minor responses; three patients (16%), mixed effects (evidence of biological effect with regression of some lesions but concomitant progression); two patients (10.5%), disease stabilization; and seven patients (37%), progressive disease. All tumor responses were seen in lung or mediastinal metastases. Tumor response significantly correlated with interferon-induced leukopenia and granulocytopenia and with pretreatment performance status. Antibodies to interferon were found in one patient prior to treatment. We concluded that interferon is a potential active antitumor agent in patients with renal cell carcinoma.

Natural killer (NK) cells as a responder to interleukin 2 (IL 2). II. IL 2-induced interferon gamma production.

Abstract: In the accompanying paper, we showed that natural killer (NK) cells were a major population in the naive spleens of normal mice that responded directly to a T cell growth factor, interleukin 2 (IL 2), and clonally replicated without other stimulating agents. The cloned cells growing in IL 2 showed a potent NK activity against several NK targets without addition of an NK-activating agent, interferon (IFN). In the present study, therefore, we examined whether these cloned NK cells on their own produced IFN. It was found that all NK clones growing in IL 2 produced IFN in the culture fluids. The titers of IFN produced in the IL 2-containing media correlated well with the number of growing cells. With the culture in the absence of IL 2, neither cell growth nor IFN production could be detected. Addition of Con A into the culture in the IL 2-free media showed no IFN production. The antiserum neutralizing IFN alpha and IFN beta failed to significantly neutralize IFN produced by NK clones. Treatment with either a pH of 2.0 or antiserum neutralizing mouse IFN gamma resulted in a marked reduction of IL 2-induced NK IFN, indicating that a major part of IFN produced was IFN gamma. These results indicate that IL 2 stimulates NK clones to proliferate, accompanied by IFN gamma production. The results also show that an NK clone, when stimulated with Sendai virus, produced a type 1 IFN (IFN alpha and/or IFN beta), suggesting that murine NK cells can produce both type 1 (alpha and/or beta) and type 2 (gamma) IFN, depending on inducers.

Capacity of human large granular lymphocytes (LGL) to produce multiple lymphokines: interleukin 2, interferon, and colony stimulating factor.

Abstract: Human large granular lymphocytes (LGL), which are known to be responsible for natural killer (NK) cell activity, also produced a variety of lymphokines including interleukin 2 (IL 2), colony stimulating factor (CSF), and interferon (IFN) in response to phytohemagglutinin (PHA) or concanavalin A (Con A). Human peripheral blood LGL, which were purified by removal of monocytes adhering to plastic flasks and nylon columns, followed by separation on a discontinuous Percoll gradient, and additional treatment with anti-OKT3 and Leu-M1 plus complement, were more potent producers of these lymphokines than unseparated mononuclear cells (MNC), nylon column-eluted cells, or purified T lymphocytes. Moreover, IL 2 production by LGL could be further distinguished in that it was not enhanced by the addition of macrophages or macrophage-derived factor, i.e., IL 1, whereas addition of macrophages did potentiate IL 2 production by T lymphocytes. Further analysis of cells in the LGL population using various monoclonal antibodies revealed that removal of cells with OKT11 or AF-10, a monoclonal antibody against human HLA-DR antigen, decreased IL 2 production, whereas removal of OKT8+, OKM1+, Leu-M1+, or Leu-7+ cells led to enhanced IL 2 production. The LGL population is therefore heterogeneous and includes at least three functionally and phenotypically distinct subsets. An atypical T cell subset (OKT3-, Leu-1-, OKT11+) rather than the myeloid subset of LGL (Leu-M1+ or OKMI+) was the source of LGL-derived IL 2, whereas the latter subset and/or another subset of OKT8+ cells appear to regulate this IL 2 production. In addition to performing NK activity, LGL on a per cell basis seem to be more effective than T lymphocytes in producing lymphokines, namely, IL2, CSF, and IFN.

Interferon induces a unique protein in mouse cells bearing a gene for resistance to influenza virus.

Abstract: Mouse cells carrying the dominant resistance gene Mx develop a more efficient antiviral state toward influenza viruses in response to interferon than do Mx-negative cells. We have identified an Mx gene-associated product by labeling cultured peritoneal macrophages and embryonic cells with [35S]methionine in the presence or absence of interferon. The radioactive proteins from unfractionated cytoplasmic extracts were separated electrophoretically in two dimensions and were revealed by fluorography. A protein with a Mr of 72,500 and an isoelectric point of 6.3 was induced by mouse interferon type I (a mixture of alpha and beta interferons) in cells carrying the gene Mx but not in cells lacking Mx. The induction of this protein could be blocked by actinomycin D. The maximal rate of synthesis was reached in embryonic cells 4-5 hr after treatment with 10(3) reference units of interferon per ml. When the allele Mx (present in the inbred mouse strain A2G) was repeatedly backcrossed on different genetic backgrounds (BALB/c, C57BL/6, A/J), a clear correlation between the inducibility by interferon of this protein and the presence of the allele Mx was observed. The results suggest that this protein induced by the interaction of interferon with Mx plays a role in the selective antiviral state against influenza viruses that is observed in interferon-treated Mx-bearing cells.

Interferons with special emphasis on the immune system

Abstract: Publisher Summary First described in 1957, interferons are induced animal proteins. A variety of stimulating substances can act as interferon inducers, and interferons inhibit a wide range of viruses by inducing an intracellular antiviral state; however, many interferons are species-specific in their antiviral activity. The suggestion that a few thousand molecules of interferon may induce an antiviral state indicates that they are among the most active biological substances. There are three general types of human interferon, designated alpha, beta, and gamma. When stimulated with virus, leukocytes in cultures produce predominantly the species called “alpha interferon.” There are at least 14 distinct genes for human alpha interferon. Most alpha interferons contain little or no carbohydrate. While human-beta interferon is usually species-specific and for the most part induces antiviral activity only in human cells, human-alpha interferons induce activity in human as well as some animal cell cultures. Gama interferon is antigenically distinct from them and is more labile to acid. Most alpha and beta interferons are quite stable at pH 2, while the antiviral activity of gamma interferon is significantly reduced.

Activation of human monocyte cytotoxicity by natural and recombinant immune interferon.

Abstract: Human T cell hybridomas were established by fusion of SH9 cells, the 6-thioguanine-resistant mutant line of human T lymphoma Hut 102-B2, with concanavalin A-stimulated human peripheral blood lymphocytes. Hybridoma line L38 produced a macrophage activating factor (MAF) with the ability to activate human peripheral blood monocytes to show enhanced cytotoxicity against human colon adenocarcinoma HT-29 cells in a 72-hr 125iododeoxyuridine-release assay. The L38 line was then cloned by the limiting dilution technique and two sublines, L38B and L38D, were found to produce high levels of MAF constitutively. Interferon activity was also detected in L38B and L38D supernatants. When interferon activity was neutralized with specific antiserum to purified human immune interferon (IFN-gamma), MAF activity was abrogated. To confirm that the MAF activity is indeed due to IFN-gamma, IFN-gamma was purified from the culture supernatant of another human T cell hybridoma, L265K2, a cell line known to produce high levels of IFN-gamma. Two highly purified IFN-gamma fractions with m.w. of 20,000 and 25,000, respectively, were obtained by NaDodSO4/polyacrylamide gel electrophoresis (SDS-PAGE). Similar fractions were obtained from IFN-gamma derived from human peripheral blood lymphocyte (PBL) cultures induced with 12-0-tetradecanoylphorbol-13-acetate (TPA) and phytohemagglutinin (PHA). In comparison, Escherichia coli-derived recombinant human IFN-gamma separated by SDS-PAGE yielded two major active fractions with m.w. of 17,000 and 34,000. With all three types of preparations, a close correlation was found between the presence of IFN-gamma activity demonstrable in an antiviral assay and MAF activity in individual fractions. Substantial quantitative differences were observed in the ability of various human IFN to activate monocytes. Although no MAF activity was detected with IFN-alpha and IFN-beta at concentrations up to 200 U/ml, both natural and recombinant IFN-gamma showed marked MAF activity at concentrations as low as 0.3 to 1 U/ml.

Functional identity between murine γ Interferon and macrophage activating factor

Abstract: We have previously suggested that two lymphokine activities–macrophage activating factor (MAF) and γ interferon (IFN-γ)–are mediated by the same molecule1,2. Striking similarities were noted in their cellular biosynthesis, rate of inactivation with acid treatment and heating, and elution profiles on Sepha-cryl S-200. In addition, highly specific polyclonal antibodies to murine IFN-γ neutralized MAF and IFN-γ to a similar degree. However, definitive studies require a pure product and we now report that murine IFN-γ that had been cloned and expressed in a simian nonlymphoid cell line shows MAF activity. But it is not yet known whether IFN-γ is responsible for all the MAF activity in media conditioned by T cells as the possibility for MAF heterogeneity remains.

Protection of mice from fatal herpes simplex virus type 1 infection by adoptive transfer of cloned virus-specific and H-2-restricted cytotoxic T lymphocytes.

Abstract: Summary A cloned culture of secondary anti-herpes simplex virus (anti-HSV) cytotoxic T lymphocytes (CTL) generated in vitro when adoptively transferred to intact or cyclophosphamide (CP) pretreated syngeneic mice protected the recipients from death following intraperitoneal infection with HSV-1. This in vivo protective effect conferred by anti-HSV CTL was virus-specific and H-2K/D-restricted. Twenty-four h after HSV-1 infection of BALB/c mice (intact or CP-pretreated) relatively high levels of serum interferon-γ were observed in the recipients of syngeneic anti-HSV CTL and this event may explain, at least in part, the CTL-mediated protective effect.

Interleukin 2 induces gamma-interferon production: participation of macrophages and NK-like cells.

Abstract: Interleukin 2 (IL 2) has been shown to be a potent stimulator of natural killer (NK) cells. In the present studies, partially purified mouse and human IL 2 preparations were also found to induce interferon (IFN) from mouse spleen cells. By the criteria of sensitivity to treatment at pH 2 and failure to be neutralized by a potent anti-alpha, beta IFN serum, the species of IFN produced was of type gamma. Cooperation between two types of cell, a macrophage and an NK-like cell, was required for IFN production by murine spleen cells treated with IL 2. The requirement for macrophages could be replaced with supernatant obtained by incubating macrophages for 24 hr with lymphokine preparations containing IL 2. Interestingly, mature T cells apparently played no role in the process. Furthermore, the beige (bg/bg) mutation, which severely impairs NK cell lytic activity, had no effect on the ability of NK-like cells to participate in IFN production. Cell fractionation experiments revealed no dissociation between the requirements for augmentation of NK cytotoxic activity and for IFN production, and it is concluded that at least a portion of the NK boosting induced by IL 2-containing preparations is mediated through gamma-IFN.

Gamma-interferon is the factor in lymphokine that activates human macrophages to inhibit intracellular Chlamydia psittaci replication.

Abstract: We have demonstrated previously that mitogen-induced lymphokines activate human monocyte-derived macrophages to inhibit the intracellular replication of Chlamydia psittaci. To identify the factor(s) in crude lymphokines responsible for this antimicrobial effect, we tested human Con A-induced lymphokines for interferon activity. We also attempted to neutralize the lymphokines with a monoclonal antibody directed against human gamma-interferon and examined the ability of partially purified human gamma-interferon to induce macrophage antichlamydial activity. The lymphokine-induced antichlamydial effect was measured by the inhibition of chlamydial inclusion formation in Giemsa-stained macrophage cultures. Our lymphokines were found to be rich in gamma-interferon; treatment of cells for 48 hr before infection with lymphokines containing 300 U/ml of interferon resulted in an 89% inhibition of chlamydial growth. This lymphokine effect was completely abolished by monoclonal antibody against human gamma-interferon, but not by antisera against human alpha- or beta-interferons. In addition, partially purified human gamma-interferon alone induced macrophages to restrict chlamydial growth by 95%. We conclude that it is the gamma-interferon present in human Con A-induced lymphokines that activates monocyte-derived macrophages to inhibit chlamydial replication.

Effects of several species of human leukocyte interferon on cytotoxic activity of NK cells and monocytes

Abstract: Ten species of purified human leukocyte interferon were tested for their ability to modulate the cytolytic activity of natural killer (NK) cells and the cytolytic and cytostatic activities of monocytes. The interferon species were tested at several antiviral titers and examined for quantitative differences in their ability to modulate immunological function. At the higher doses of interferon (i.e., greater than 500 units) all of the interferon species demonstrated significant augmentation of cytolysis and cytostasis. However, when low levels (i.e., 10-50 units) of interferon were employed, appreciable differences between the various interferon species were seen. A similar pattern of relative potency among the various species of pure leukocyte interferon was seen for augmentation of cytolysis by monocytes and NK cells. In contrast, a different pattern of relative potency was observed for augmentation of cytostasis. These results demonstrated substantial quantitative differences (as much as 100-fold) in the ability of the various species of human leukocyte interferon to induce significant levels of augmentation of these cell-mediated functions. Such results should have significant impact in choosing a specific interferon species for appropriate clinical trials.

Interleukin 2 enhances natural killer cell activity through induction of gamma interferon.

Abstract: Highly purified interleukin 2 (IL 2), free of interferon activity, enhanced natural killer (NK) cell activity against tumor cells in mouse spleen cell cultures and in human peripheral lymphocyte cultures in a manner similar to that of interferon (IFN). We determined that IL 2 enhanced NK activity indirectly in a cascade manner by the induction of gamma IFN (IFN-gamma) in the cultures, which actually mediated the enhanced killing. Accordingly, lymphocyte cultures treated with IL 2 alone produced 10 to 100 U of IFN per ml in 6 to 24 h of culture. The IFN was typed as IFN-gamma by specific antibodies. Specific antibodies either to natural IFN-gamma or to a synthetic peptide corresponding to the human IFN-gamma N-terminal amino acids, when added to cultures treated with IL 2, completely blocked IL 2 enhancement of NK cell activity for both the mouse and human systems. IL 2-induced proliferation was not affected by the antibodies. Thus, the enhancement of NK cell activity by IL 2 is completely mediated by IL 2-induced IFN-gamma. The findings clearly indicate a cascade effect whereby one lymphokine (IL 2) induces the production of another. The latter lymphokine (IFN-gamma) then mediates an important biological effect (natural killing).

Direct Suppression of Natural Killer Activity in Human Peripheral Blood Leukocyte Cultures by Glucocorticoids and Its Modulation by Interferon

Abstract: In vitro treatment of human peripheral blood leukocytes for 18 to 24 hr with physiological concentrations of glucocorticoids resulted in a marked decrease (up to 90%) in natural killer (NK) activity. The effect on NK activity was both dose and time dependent and was specific for glucocorticoids. Glucocorticoids had no effect when added directly to the 4-hr 51Cr release cytotoxicity assay, nor did they alter the susceptibility of K562 cells to NK-mediated cytolysis. Glucocorticoid-induced inhibition occurred in Percoll-fractionated peripheral blood leukocytes enriched for NK activity. Viabilities of steroid-treated and untreated cultures were similar. Mixing experiments failed to demonstrate the involvement of suppressor activity in the inhibition. Purified cloned human leukocyte interferon subtype A and inducers of interferon enhanced NK activity in the presence of glucocorticoid, although the levels of enhancement were lower than those produced by these agents in the absence of the steroid. Thus, glucocorticoids appear to suppress human NK activity by interacting directly with the NK effector cell, and our results obtained with physiological concentrations of these steroids suggest that they may play an important role in regulating NK activity in vivo. Additionally, these findings suggest a possible means for overriding this immunosuppressive side effect of glucocorticoid therapy by simultaneous treatment with interferon.

Effects of cloned human leukocyte interferons in the human tumor stem cell assay.

Abstract: Clonogenic tumor cells from fresh biopsies of human cancers were cultivated in vitro and tested for sensitivity by continuous exposure to pharmacologically achievable concentrations of either of two highly purified human leukocyte interferon subtypes (IFN-alpha A and IFN-alpha D) prepared by recombinant DNA methods. The interferons were compared on a weight basis at concentrations of 0.4 and 4.0 ng/ml (equivalent to 80 and 800 units of interferon activity for IFN-alpha A and 2.0 and 20 units for IFN-alpha D). Inhibition of tumor colony-forming units (50% of control or less) was observed in 38.1% of the 273 tumors tested against IFN-alpha A, and in 16% of the 71 tumors tested against IFN-alpha D. Of the tumor types with at least ten samples tested against IFN-alpha A, the percentage of cases exhibiting inhibition was as follows: melanoma (51.7%), lung cancer (50%), myeloma (33.4%), ovarian cancer (33.9%), sarcoma (33.3%), adenocarcinoma of unknown primary (30.4%), breast cancer (28%), acute leukemia (30.8%...

Reversible induction of natural killer cell activity in cloned murine cytotoxic t lymphocytes.

Abstract: Reversible induction of natural killer cell activity in cloned murine cytotoxic T lymphocytes

Two levels of regulation of beta-interferon gene expression in human cells.

Abstract: We cloned alpha- and beta-interferon cDNA and used them as specific probes to determine the relative levels of interferon mRNA in human fibroblasts cells induced with poly(rI).poly(rC) or Newcastle disease virus to synthesize interferon. Both inducers activated only the beta-interferon gene; however, the half life of beta-interferon mRNA in cells induced with virus was substantially longer than in poly(rI).poly(rC)-induced cells. The transcription rate of beta-interferon RNA sequences was examined in nuclei isolated from poly(rI).poly(rC)-induced cells; it was found that the induction leads to transcriptional activation of the beta-interferon gene and that the shutoff period when no interferon synthesis or cytoplasmic betamRNA are detected. Thus, the synthesis of beta interferon in poly(rI).poly-(rC)-induced human fibroblasts is controlled both by activation of transcription of the beta-interferon gene and by alteration of the beta-interferon mRNA stability.

The beta2-microglobulin mRNA in human Daudi cells has a mutated initiation codon but is still inducible by interferon.

Abstract: The human Burkitt lymphoma cell line Daudi does not synthesize beta2-microglobulin (beta2m) and lacks the cell surface histocompatibility antigens. The cells, however, contain RNA hybridizing to a cloned human beta2m cDNA probe. cDNA from this Daudi beta2m RNA, was cloned and sequenced. By comparison with cDNA prepared from Ramos cells, which synthesized microglobulin, we determined the sequence of the 20 amino acid long leader peptide of pre-beta2m and show that in Daudi cells the initiator ATG has been mutated to ATC. Although Daudi beta2m RNA cannot be translated, interferon induces the beta2m RNA in Daudi cells as well as in normal human cells.

Defective gamma interferon production in leprosy. Reversal with antigen and interleukin 2.

Abstract: Antigen and mitogen-induced gamma interferon (gamma-IFN) production was studied in peripheral blood mononuclear cells from 34 leprosy patients. 17 of 18 lepromatous leprosy and borderline lepromatous patients (LL and BL) failed to release gamma-IFN in response to specific antigen (Mycobacterium leprae) and displayed reduced responses to mitogen (concanavalin A) stimulation. In contrast, cells from six tuberculoid and borderline tuberculoid patients (TT and BT) produced considerable levels of gamma-IFN under the same experimental conditions. Normal controls failed to respond to M. leprae and most displayed good responses to concanavalin A. Mid-borderline patients (BB) showed intermediate levels of gamma-IFN release. gamma-IFN release by lepromatous patients could be partially restored with purified interleukin 2 and M. leprae antigen but not with interleukin 2 alone.

Interferons as macrophage‐activating factors. II. Enhanced secretion of interleukin 1 by lipopolysaccharide‐stimulated human monocytes

Abstract: Human adherent monocytes were incubated with interferon (IFN) preparations, then washed and stimulated with endotoxins. The interleukin (IL1) activity in the supernatants of IFN-treated monocyte cultures was found to be increased as compared to control (not pretreated) cultures. This phenomenon was observed whether alpha or beta IFN was used, and was completely abolished by antiserum to the relevant IFN. IL1 secretion of IFN-treated monocyte cultures could be triggered by suboptimal dosage of endotoxins, unable to induce any IL1 activity in control medium-treated cultures. IFN was highly efficient in this system, since very low concentrations (of the order of 2 units) were effective. Since IFN alone, without endotoxin stimulation, was unable to induce IL1 secretion, the results indicate that IFN is able to activate monocytes, by inducing a potential secretory capable rather than an ongoing IL1 secretion function. The ability of IFN to enhance the IL1 secretory potential of human monocytes may be relevant to the known immunoenhancing effects of IFN preparations and to the pyrogenic effects of IFN administration in patients.

Interferon-induced 2'-5' adenylate synthetase in vivo and interferon production in vitro by lymphocytes from systemic lupus erythematosus patients with and without circulating interferon.

Abstract: The interferon (IFN)-induced enzyme 2-5A synthetase was elevated in mononuclear cells from both serum IFN-positive and -negative systemic lupus erythematosus (SLE) patients. This suggests that a much higher percentage of patients than previously thought produce endogenous IFN. These results may partly explain findings that mononuclear cells from SLE patients are deficient in IFN production in vitro in response to certain IFN inducers. Although normal lymphocytes can produce an acid-labile alpha IFN after stimulation with C. parvum in vitro, the reason for endogenous production of this unusual alpha IFN by SLE patients remains unknown.