Interrelationships of human interferon-gamma with lymphotoxin and monocyte cytotoxin

A fascinating story of the discovery & development of biologicals for use in clinical medicine

A young physician starting a fresh career in medicine in this millennium would hardly stop to think about the genesis of a particular biological drug that he/she will be prescribing for a patient evaluated in the morning outpatient department. For him/her, this is now routine, and the question of 'Who', 'How' and 'When' about these biologicals would be the last thing on their mind. However, for those who came to the medical profession in the 1950s, 1960s and 1970s, these targeted drugs are nothing short of 'miracles'. It would be a fascinating story for the young doctor to learn about the long journey that the dedicated biomedical scientists of yesteryears took to reach the final destination of producing such wonder drugs. The story is much like an interesting novel, full of twists and turns, heart-breaking failures and glorious successes. The biologicals acting as 'targeted therapy' have not only changed the natural history of a large number of incurable/uncontrollable diseases but have also transformed the whole approach towards drug development. From the classical empirical process, there is now a complete shift towards understanding the disease pathobiology focusing on the dysregulated molecule(s), targeting them with greater precision and aiming for better results. Seminal advances in understanding the disease mechanism, development of remarkably effective new technologies, greater knowledge of the human genome and genetic medicine have all made it possible to reach the stage where artificially developed 'targeted' drugs are now therapeutically used in routine clinical medicine.

On-line capillary isoelectric focusing hyphenated to native electrospray ionization mass spectrometry for the characterization of interferon-γ and variants

The on-line hyphenation of Capillary IsoElectric Focusing (CIEF) with ElectroSpray Ionization Mass Spectrometry (ESI/MS) has been carried out in a non-denaturing detection mode at the CIEF-MS interface.

Curcumin: an orally bioavailable blocker of TNF and other pro-inflammatory biomarkers

TNFs are major mediators of inflammation and inflammation-related diseases, hence, the United States Food and Drug Administration (FDA) has approved the use of blockers of the cytokine, TNF-α, for the treatment of osteoarthritis, inflammatory bowel disease, psoriasis and ankylosis. These drugs include the chimeric TNF antibody (infliximab), humanized TNF-α antibody (Humira) and soluble TNF receptor-II (Enbrel) and are associated with a total cumulative market value of more than $20 billion a year. As well as being expensive ($15 000-20 000 per person per year), these drugs have to be injected and have enough adverse effects to be given a black label warning by the FDA. In the current report, we describe an alternative, curcumin (diferuloylmethane), a component of turmeric (Curcuma longa) that is very inexpensive, orally bioavailable and highly safe in humans, yet can block TNF-α action and production in in vitro models, in animal models and in humans. In addition, we provide evidence for curcumin's activities against all of the diseases for which TNF blockers are currently being used. Mechanisms by which curcumin inhibits the production and the cell signalling pathways activated by this cytokine are also discussed. With health-care costs and safety being major issues today, this golden spice may help provide the solution.

LINKED ARTICLES

This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.

Inhibitory Effect of TNF-α Produced by Macrophages Stimulated withGrifola frondosaExtract (ME) on the Growth of Influenza A/Aichi/2/68 Virus in MDCK Cells

We investigated the inhibitory effect of the conditioned medium (CM) from P338D1 (D1) cells, a murine macrophage cell line, stimulated for 10 hours with a fixed dose (100 μg/ml) of the extracts from the fruit bodies of Grifola frondosa (ME) or its ultra filtration-based fractions (MFs), on the growth of influenza A/Aichi/2/68 virus in Madin-Darby canine kidney cells. Direct addition of ME and 3 kinds of MFs (MF1, MF2 and MF3) to the infected cells had no obvious inhibitory effect. However, virus yields were reduced in the presence of CMs. Notably, the inhibitory effect of the CM prepared by using MF2 (molecular weight of 30 Kd to 100 Kd) was the strongest (28% reduction compared to the control). RT-PCR and ELISA assays showed that the CMs could induce the expression of TNF-α mRNA in D1 cells leading to production of TNF-α, known as an antiviral cytokine. These findings suggest that ME and MFs (especially MF-2) might induce the production of certain factors, including TNF-α, which are responsible for the inhibition of viral growth in vitro.

Lymphotoxin: cloning, regulation and mechanism of killing

The gene for murine lymphotoxin (MuLT) has been cloned from a cDNA library prepared using poly(A)+ RNA from an activated murine IL-2-maintained cloned T cell line (21C11). This was accomplished with a MuLT BamHI fragment isolated from a murine genomic library by hybridization to a human LT cDNA probe. Northern blot analysis with RNA from 21C11, an L3T4+ (CD4+-equivalent) ovalbumin-specific class II-restricted T cell line, revealed a 15S band that hybridized to this MuLT fragment. A cDNA library prepared with poly(A)+ RNA from 21C11 cells contained 36 colonies that hybridized with the MuLT BamHI fragment. A full-length cDNA has been isolated, sequenced, expressed in COS-1 cells and used to map MuLT to mouse chromosome 17. The sequence and structure of the MuLT gene has been determined. MuLT cDNA has been used to analyse mRNA expression in several L3T4+ and Lyt-2+ (CD8+-equivalent) T cell clones activated with antigen, mitogen, or antibody to the T cell receptor. LT is expressed by both class I- and class II-restricted T cells. The mechanism of killing by both LT and the functionally related molecule TNF-alpha includes the induction of DNA fragmentation in the target cell.

Historical review: Cytokines as therapeutics and targets of therapeutics

Cytokine research has spawned the introduction of new therapies that have revolutionized the treatment of many important diseases. These therapeutic advances have resulted from two very different strategies. The first therapeutic strategy embodies the administration of purified, recombinant cytokines. The second relies on the administration of therapeutics that inhibit the harmful effects of upregulated, endogenous cytokines. Examples of successful cytokine therapeutics include hematopoietic growth factors (colony stimulating factors) and interferons. Prime examples of cytokine antagonists that have profoundly altered the treatment of some inflammatory disorders are agents that inhibit the effects of tumor necrosis factor (TNF). In this article, we highlight some of the studies that have been responsible for the introduction of cytokine and anti-cytokine therapies, with emphasis on the development of interferons and anti-TNF agents.

Interferon-gamma regulates apoptosis by releasing soluble tumor necrosis factor receptors in a gastric epithelial cell line

BACKGROUND AND AIMS

Interferon (IFN)-gamma and tumor necrosis factor (TNF) are predominant cytokines produced in the gastric mucosa of patients with Helicobacter pylori-infected gastritis. Several studies reported that IFN-gamma and TNF induced the synergistic effect on many cell lines. We attempted to clarify the apoptotic activity and the synergistic effect of IFN-gamma and TNF on the gastric epithelial cell, and whether IFN-gamma relates to soluble TNF receptors (sTNF-R) release from the gastric epithelial cell.

METHODS

On the gastric epithelial cell line MKN45, cytotoxic and apoptotic effects of IFN-gamma and TNF were examined. Next, sTNF-R released in response to IFN-gamma and the protective effect of sTNF-R against the cytotoxic activity of TNF and IFN-gamma were examined by blocking the release of sTNF-R with a serine protease inhibitor such as phenylmethylsulfonyl fluoride.

RESULTS

Interferon-gamma significantly decreased cell viability, but TNF decreased it only slightly. Interferon-gamma and TNF did not make a synergistic effect on cell viability and apoptosis. Interferon-gamma and TNF induced sTNF-R release from gastric epithelial cells. Phenylmethylsulfonyl fluoride significantly inhibited shedding of sTNF-R and a synergistic effect of TNF and IFN-gamma on apoptosis was observed.

CONCLUSION

These results suggest that sTNF-R released by IFN-gamma regulate the injury on the gastric epithelial cell line induced by TNF.

Synergistic cytotoxicity of Rana catesbeiana ribonuclease and IFN-gamma on hepatoma cells

RC-RNase purified from Rana catesbeiana (bullfrog) oocytes is a pyrimidine-guanine sequence-specific ribonuclease. RC-RNase is derived from the RNase superfamily genes exerting distinct ribonucleolytic activity and possesses cytotoxicity to tumor cells, but rarely to primary cells. In this study, we utilized RC-RNase to function with antiproliferative cytokines. The combination with TNF-alpha or TNF-beta would not aggravate cell death. However, the combination with IFN-gamma could induce synergistic cytotoxicity verified by XTT assays toward three hepatoma cell lines bearing different differentiation stages. The distinct cytotoxicity from RC-RNase or RC-RNase/IFN-gamma on different hepatoma cells was correlated with the differentiation extent but not the proliferation rate of the cells. Despite the synergistic cytotoxicity and severe mitochondrial disruptions in the RC-RNase/IFN-gamma-treated cells, we scarcely detected any significant feature of apoptosis or necrosis by FACS analysis on annexin-V/propidium iodide staining. The mechanisms of cell death triggered by RC-RNase or RC-RNase/IFN-gamma require further investigation.

IFN-alpha suppresses activation of nuclear transcription factors NF-kappa B and activator protein 1 and potentiates TNF-induced apoptosis

We and others have reported that IFN-alpha potentiates the apoptotic effects of TNF through a mechanism that is not understood. Because the nuclear transcription factors NF-kappaB and AP-1 have recently been reported to mediate anti-apoptosis and cell survival, we hypothesized that IFN-alpha potentiates the cytotoxic effects of TNF by suppressing TNF-induced activation of NF-kappaB and AP-1. We tested this hypothesis by pretreating human Jurkat T cells with IFN-alpha, which blocked TNF-induced activation of NF-kappaB and AP-1 in a time- and dose-dependent manner as determined by EMSA. IFN-alpha blocked TNF-induced phosphorylation and degradation of the inhibitor subunit of NF-kappaB, and suppressed NF-kappaB and AP-1 activation induced by various other inflammatory stimuli. NF-kappaB-dependent reporter gene expression activated by TNF, TNFR1, TNF receptor-associated factor 2, and NF-kappaB-inducing kinase was also abrogated by IFN-alpha pretreatment. The suppression of NF-kappaB and AP-1 correlated with the potentiation of TNF-induced cytotoxicity and caspase activation. Overall our results suggest that IFN-alpha potentiates the apoptotic effects of TNF possibly by suppressing NF-kappaB and AP-1 activation.

TNF-related ligands and their receptors

Multicellular organisms have the challenging task of coordinating the activities of many distinct cell types. This coordination is accomplished largely by cell-associated and soluble signalling molecules that act locally or distantly to alter target-cell physiology. The tumour necrosis factor family of cytokines are type II transmembrane proteins that are important regulators of homeostasis and have been implicated as mediators of disease. These molecules serve as ligands for a family of cell-surface receptors termed the tumour necrosis factor/nerve growth factor (TNF/NGF) receptor family. The receptors are type I transmembrane proteins capable of mediating a wide range of responses in vitro and in vivo. Signal transduction is mediated by several newly discovered cytoplasmic proteins that couple these receptors to downstream signalling events. The elucidation and use of spontaneously occurring mutants in TNF-related ligands and receptors in addition to gene-targeting experiments have begun to clarify the diverse biological effects mediated by this superfamily of cytokines.

Down-regulation of human tumor necrosis factor-beta gene expression by cells with suppressive activity

Human TNF-beta (lymphotoxin) gene expression is down-regulated by immunosuppression. Induction of TNF-beta mRNA in lymphoid cells is greatly enhanced by gamma-irradiation, cyclophosphamide and cimetidine, agents that each inhibit activation of suppressive cells. The level of TNF-beta mRNA expressed in response to stimulation, whether by mitogen or antigen, is reduced strongly by concomitant activation of suppressive cell subsets. Removal of CD8 or CD11b cells leads to a pronounced superinduction of TNF-beta mRNA in the depleted cell population. Induction of TNF-beta mRNA precedes appearance of suppressive cell activity, allowing for temporary expression. The TNF-beta gene is as sensitive as IFN-gamma and IL-2 genes to suppression. Hence, three genes characteristically expressed in Th1 cells, encoding IL-2, IFN-gamma, and TNF-beta, are similarly regulated by cell-mediated suppression. Actual levels of TNF-beta during an immune response are determined by the balance between activities of expressing and suppressing cell subsets, both transiently manifested.

Prolactin and insulin regulate the release of IL-1-alpha and IFN-gamma from murine splenocytes activated with porins or LPS of Salmonella typhimurium

Murine splenocytes treated with prolactin (PRL) or insulin were stimulated in vitro with porins or lipopolysaccharide (LPS) of Salmonella typhimurium. It was seen that PRL inhibits the release of IFN-gamma from splenocytes treated with porins by about 20% while having no effect on the release of IL-1-alpha. Splenocytes porin-stimulated splenocytes exhibited a remarkable increase in IL-1-alpha release (100%) and a diminished release of IFN-gamma (about 50%) in the presence of insulin. The splenocytes stimulated with LPS had a reduced release of IL-1-alpha (75%) and IFN-gamma (about 50%) when insulin was added. The data suggest that classical endocrine system participates in a bioregulatory feedback loop that may prevent unwanted toxicity from cytokine excess. However, some bacterial products sometimes enormously unbalance this regulatory network.

Effect of tumor necrosis factor-alpha and interferon-gamma on the growth of human prostate cancer cell lines

Human recombinant tumor necrosis factor-alpha (rTNF-alpha, 10(-12)-10(-8) M) inhibited the proliferation of androgen-dependent LNCaP cells by 32-56%. In contrast, proliferation of androgen-independent PC-3 and JCA-1 cells was only slightly inhibited, or not inhibited at all, respectively. Human recombinant interferon-gamma (rIFN-gamma, 500 U/ml) decreased proliferation of PC-3 and JCA-1 cells by 35% and 53%, respectively, but had no effect on LNCaP cells. Interestingly, the combination of rIFN-gamma and TNF-alpha had greater antiproliferative effects on JCA-1 cells than treatment with either cytokine alone. However, the antiproliferative effects of this combination were similar to those observed for PC-3 or LNCaP cells treated with rIFN-gamma or TNF-alpha alone, respectively. These data suggest that some forms of androgen-independent prostate cancer may benefit from a combination therapy of IFN-gamma and TNF-alpha, while the use of IFN-gamma alone may be more efficacious in others.

Thyroid cell survival in coculture with autologous peripheral or intrathyroidal lymphocytes

OBJECTIVE

We have studied lymphocyte induced cytotoxicity and the production of interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) during coculture of thyrocytes and autologous lymphocytes from patients with Graves' disease and from normal subjects.

PATIENTS

Thyroid tissues and lymphocytes were obtained from 28 patients with Graves' disease and from 9 control subjects.

MEASUREMENTS

Lymphocyte induced cytotoxicity was evaluated on autologous thyrocytes using 5 metabolic tests: the MTT assay, the neutral red uptake, lactate dehydrogenase measurement and glutathione assay. IFN-gamma and TNF-alpha measurements were performed after 1, 5 or 7 days' coculture.

RESULTS

The lymphocytes isolated from peripheral blood (PB lymphocytes) altered the morphology and the metabolism of autologous thyrocytes. The intrathyroidal lymphocytes isolated after Dispase digestion were not toxic whereas mechanically isolated lymphocytes exerted a little toxicity. No difference was seen between Graves' disease and normal cells. The supernatants from cocultures had higher IFN-gamma levels than those from lymphocyte cultures. In coculture, PB lymphocytes secreted more IFN-gamma and TNF-alpha than intrathyroidal lymphocytes. The PB lymphocyte induced cytotoxicity was not due to IFN-gamma and TNF-alpha alone.

CONCLUSION

Peripheral blood lymphocytes are cytotoxic in vitro to autologous thyrocytes whereas intrathyroidal lymphocytes exert little or no cytotoxicity according to their isolation method. The mechanisms of lymphocyte induced toxicity remain to be explained.

Induction of tumour necrosis factor-alpha (TNF-alpha) mRNA in bladders and spleens of mice after intravesical administration of bacillus Calmette-Guérin

Intravesical bacillus Calmette-Guérin (BCG) therapy is highly effective in the therapy of carcinoma in situ of the bladder, but the mechanism of BCG immunotherapy is not clearly understood. We studied the production of TNF-alpha in spleens and bladders of mice after intravesical BCG or BCG/interferon-gamma (IFN-gamma) instillation. Significant change of TNF-alpha mRNA expression of spleens and bladders of C3H/He mice was observed after intravesical BCG instillation, although intravesical IFN-gamma therapy 3 days after BCG instillation to maintain the activated state of monocyte/macrophage lineage cells did not show a significant change of TNF-alpha mRNA, compared with that of BCG therapy alone. Maximal production of TNF-alpha mRNA in spleens of mice was seen after the first or second intravesical BCG instillation, and production of TNF-alpha mRNA in bladders was also increased after intravesical BCG instillation. The increment of TNF-alpha production by BCG stimulation in HL-60, a promyelocytic leukaemic cell line, and peripheral blood mononuclear cells in vitro may support the in vivo effect of BCG therapy on the bladder. These data show that local production of TNF-alpha as well as systemic production by intravesical BCG treatment may correlate with one of the mechanisms of BCG immunotherapy of superficial bladder cancer.

Effect of interferon gamma and tumour necrosis factor alpha on sensitivity to cisplatin in ovarian carcinoma cell lines

This study aimed to investigate whether the biological response modifiers (BRM) interferon gamma (IFN gamma) and tumour necrosis factor alpha (TNF alpha) could enhance the cytotoxic action of cisplatin on ovarian tumour cells in vitro. The sensitivity of four cell lines (OAW42, GG, JAM and PE01) to drugs and drug combinations was tested by a radiolabelled-thymidine incorporation assay. Cell lines demonstrated a range of sensitivity to cisplatin and the innate cytotoxic effect of each of the BRM. When IFN gamma was used in combination with cisplatin, a significant enhancement of cisplatin toxicity occurred in three of four cell lines. TNF alpha demonstrated such an effect in two cell lines but diminished the toxicity of cisplatin in one cell line. A purely additive effect of the agents may explain the enhanced toxicity of cisplatin in some of these cases. However, in one cell line at least (PEO1), both TNF alpha and IFN gamma demonstrated a clearly synergistic effect with cisplatin. These BRM used in conjunction with cisplatin may provide better antitumour regimen than cisplatin alone in some patients with ovarian cancer, but the response is likely to be heterogeneous between patients.

The interferons: a biological system with therapeutic potential in viral infections

Successful medical use of interferon for chronic viral infections is increasingly dependent on understanding the biologic and molecular mechanisms of the interferon system. Interferon (IFN) is one of the body's natural defenses. Production of IFN is a defensive response to foreign components of microbes, tumors and antigens. This IFN response begins with the production of the IFN proteins (alpha, beta and gamma) which then induce antiviral, antimicrobial, antitumor, and immunomodulatory actions. Thus, the initial production or administration of IFN(s) does not protect directly but instead reacts with specific receptors on cell surfaces to activate cytoplasmic transduction signals that then enter the nucleus to stimulate cellular genes encoding a number of effector proteins which lead to the defensive actions. The known molecular, humoral and cellular mechanisms by which these effector proteins exert their antiviral activities are presented. In addition, the pathogenesis of chronic infections is overviewed in the context of the interferon defenses.

Interferon-gamma induces a decrease in the susceptibility of human glioma cells to lysis by lymphokine-activated killer cells

We studied the effect that treating two types of glioblastoma cell lines, U-87 MG and U-251 MG, with interferon (IFN)-gamma had on their susceptibility to lysis by lymphokine-activated killer (LAK) cells. We also examined the participation of cell-adhesion molecules and major histocompatibility complex (MHC) class I and II antigens present on the target cells in lysis by LAK cells. Treatment with IFN-gamma (1000 U/ml) for 48 hours resulted in the increased expression of both intercellular-adhesion molecule 1 and MHC class I antigens on tumor cells. In addition, untreated tumor cells expressed neural-cell-adhesion molecules and MHC class II antigens highly, but their expression was not affected by IFN-gamma treatment. These changes in expression were accompanied by a decreased susceptibility to lysis by LAK cells. Treatment with antisense-intercellular-adhesion molecule-1 oligonucleotide further inhibited LAK lysis of target cells, following treatment with IFN-gamma. In contrast, acid treatment of tumor cells after treatment with IFN-gamma increased their susceptibility to lysis by LAK cells. These findings suggest that treatment of glioblastoma cells with IFN-gamma decreased their susceptibility to lysis by LAK cells, and that this decrease in susceptibility is attributable principally to the increased expression of MHC class I antigen on target cells.

Identification and sequence of an accessory factor required for activation of the human interferon gamma receptor

Human chromosomes 6 and 21 are both necessary to confer sensitivity to human interferon gamma (Hu-IFN-gamma), as measured by induction of class I human leukocyte antigen (HLA) and protection against encephalomyocarditis virus (EMCV) infection. Whereas human chromosome 6 encodes the Hu-IFN-gamma receptor, human chromosome 21 encodes accessory factors for generating biological activity through the Hu-IFN-gamma receptor. Probes from a genomic clone were used to identity cDNA clones expressing a species-specific accessory factor. These cDNA clones are able to substitute for human chromosome 21 to reconstitute the Hu-IFN-gamma receptor-mediated induction of class I HLA antigens. However, the factor encoded by the cDNA does not confer full antiviral protection against EMCV, confirming that an additional factor encoded on human chromosome 21 is required for reconstitution of antiviral activity against EMCV. We conclude that this accessory factor belongs to a family of such accessory factors responsible for different actions of IFN-gamma.

Both type I and type II interferons down-regulate human tumor necrosis factor receptors in human hepatocellular carcinoma cell line Hep G2. Role of protein kinase C

It is well known that interferon-gamma (IFN-gamma; type II) potentiates various responses of human tumor necrosis factor (TNF) in a wide variety of cells and that this potentiation is accompanied by the up-regulation of TNF receptor synthesis. In the present studies we examined the regulation of TNF receptors by type I and type II IFNs in a hepatocellular carcinoma cell line, HEP G2. Exposure of these cells to IFN-gamma led to a decrease in TNF receptor number (4029 vs. 2719 sites/cell) without any change in the receptor affinity (0.96 nM vs. 1.1 nM). The effect was time and dose-dependent. Like IFN-gamma, IFN-alpha and IFN-beta (type I) down-modulated the TNF receptors on these cells. The effect of IFNs on the TNF receptors was inhibited by staurosporin, a protein kinase C (PK-C) inhibitor. Furthermore, by the use of receptor-specific antibodies, we found that the IFN-dependent decrease was primarily due to the p60 form of the TNF receptor. Our results presented are the first to demonstrate that IFNs can also down-modulate TNF receptors in certain cells and that this effect is mediated through PK-C.

Identification of a yeast artificial chromosome clone encoding an accessory factor for the human interferon gamma receptor: evidence for multiple accessory factors

Human chromosomes 6 and 21 are both necessary to confer sensitivity to human interferon gamma (Hu-IFN-gamma), as measured by the induction of human HLA class I antigen. Human chromosome 6 encodes the receptor for Hu-IFN-gamma, and human chromosome 21 encodes accessory factors for generating biological activity through the Hu-IFN-gamma receptor. A small region of human chromosome 21 that is responsible for encoding such factors was localized with hamster-human somatic cell hybrids carrying an irradiation-reduced fragment of human chromosome 21. The cell line with the minimum chromosome 21-specific DNA is Chinese hamster ovary 3x1S. To localize the genes further, 10 different yeast artificial chromosome clones from six different loci in the vicinity of the 3x1S region were fused to a human-hamster hybrid cell line (designated 16-9) that contains human chromosome 6q (supplying the Hu-IFN-gamma receptor) and the human HLA-B7 gene. These transformed 16-9 cells were assayed for induction of class I HLA antigens upon treatment with Hu-IFN-gamma. Here we report that a 540-kb yeast artificial chromosome encodes the necessary species-specific factor(s) and can substitute for human chromosome 21 to reconstitute the Hu-IFN-gamma-receptor-mediated induction of class I HLA antigens. However, the factor encoded on the yeast artificial chromosome does not confer antiviral protection against encephalomyocarditis virus, demonstrating that an additional factor encoded on human chromosome 21 is required for the antiviral activity.

Synergistic anti-HSV effect of tumor necrosis factor alpha and interferon gamma in human corneal fibroblasts is associated with interferon beta induction

HSV-1 (17) replicated to high titer in human corneal fibroblasts (> 10(8) PFU/10(5) cells) following infection at one PFU per 100 cells. Pretreatment of the cells for 24 h with 50 U/ml recombinant human tumor necrosis factor alpha (TNF-alpha) or 5 IU/ml of human interferon gamma (IFN-gamma) resulted in only modest reduction (2- to 19-fold) in virus yield. However, when the two cytokines were combined the antiviral effect was dramatically increased. There was > 1000-fold reduction in virus titer in 8 of 8 trials. In contrast, the combinations of 50 U/ml TNF-alpha with 5 IU/ml IFN-alpha or IFN-beta did not produce a synergistic effect. The pronounced synergistic antiviral activity of TNF-alpha+IFN-gamma could be demonstrated in fibroblast cultures from different donors, and HSV-2 as well as HSV-1 strains were inhibited. There was no evidence that dual cytokine treatment was toxic for uninfected or HSV-infected cells. Insight into the mechanism responsible for the synergistic effect was provided by the observation that TNF-alpha+IFN-gamma induced IFN-beta. In addition, anti-IFN-beta but not anti-IFN-alpha antibodies could reverse the antiviral effect, and reconstitution with IFN-beta could duplicate the phenomenon. We conclude that the combination of TNF-alpha and IFN-gamma at low concentrations can exert a powerful anti-herpes effect in human corneal fibroblasts which can be chiefly attributed to the induction of IFN-beta.

Simultaneous electroelution of whole SDS-polyacrylamide gels for the direct cellular analysis of complex protein mixtures

A novel procedure which allow the rapid screening of complex protein mixtures in cellular assays is described. A device has been developed which allows a convenient, simultaneous electroelution of separated proteins from whole SDS polyacrylamide gels into narrow chambers each containing single or a few protein bands. We have optimized the conditions of the procedure and have obtained an efficient removal of SDS, leading to non-toxic protein fractions in a physiological buffer suited for direct testing in cell cultures. The responses generated by stimulating lymphocytes with the purified products have been compared to the native protein and a corresponding preparation of protein transferred to nitrocellulose particles. The method was used to investigate murine T cell responses to secreted mycobacterial antigens during infection with M. tuberculosis. A immunodominant secreted protein fraction was purified in a semipreparative scale by the procedure and used to immunize mice. The specificity of and lymphokine production by T cells generated in these animals were investigated. The device developed has various applications and provides a tool for the possible identification of new T cell antigens of importance for protective immunity.

Tumour necrosis factor-alpha augments the expression of Fc IgE receptor (Fc epsilon RII/CD23) on human monocytic cell lines and down-regulates interleukin-4-driven Fc epsilon RII expression on monocytes

We investigated the expression of the low affinity Fc IgE receptor (Fc epsilon RII/CD23) on the human monocytic cell lines U937, THP-1, Mono-Mac-6, and cultured human peripheral blood monocytes under stimulation with human tumour necrosis factor-alpha (TNF-alpha) and other cytokines. Fc epsilon RII was demonstrated by flow cytometry analysis employing the anti-Fc epsilon RII monoclonal antibody 3-5. TNF-alpha alone had a weak but significant stimulating effect on the Fc epsilon RII expression on the cell lines U937 and THP-1, and very modestly on Mono-Mac-6 cells. TNF-alpha strongly synergized with interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). IFN-alpha per se was ineffectual, but was able to increase the TNF-alpha effect. Furthermore, the action of TNF-alpha was slightly augmented by human IL-6. Similar effects were noted with TNF-beta alone or in combination with other cytokines. Interestingly, on human monocytes TNF-alpha weakly reduced the basal level of Fc epsilon RII, and markedly diminished the IL-4-induced Fc epsilon RII expression. Our results indicate that several cytokines may interact in a cytokine network to modulate Fc epsilon RII expression on monocytic cell lines. On human blood monocytes, TNF-alpha, like IFN-gamma or IL-6, counteracts the IL-4-induced Fc epsilon RII expression. These data suggest different regulatory pathways of Fc epsilon RII expression on blood monocytes and myelomonocytic cell lines.

Isolation of a novel cytotoxic lymphokine (factor 2) from a human B-cell line (Karpas 160b) by preparative isoelectric focusing in the rotofor cell and chromatofocusing

Preparative isoelectric focusing (IEF) using a Rotofor cell was used for the isolation of a biologically active form of a novel cytotoxic lymphokine (Factor 2, F2) produced by a human B-cell line (Karpas 160b). We found that F2 either purified by DE52 or extracted from 160b cells using CHAPS, after adding octyl glucoside to 0.05%, could be electrofocused in the Rotofor cell without the addition of carrier ampholytes. Better recovery and separation were also achieved in the presence of 0.5% CHAPS, 3M urea. We compared the fractionation of F2 by chromatofocusing and IEF in Rotofor. Our results also showed that F2 was separable from tumor necrosis factor and phorbol myristate acetate-associated cytotoxicity by one step IEF in Rotofor. F2 purified by DE52, S-300 and Mono Q was further purified by IEF in Rotofor.

Interferon-gamma induces cell surface expression for both types of tumor necrosis factor receptors

Interferons are known to potentiate various biological effects of tumor necrosis factor (TNF). Recently, two different types of TNF receptors with molecular masses of 60 kDa (p60) and 80 kDa (p80), primarily expressed by epithelial cells and myeloid cells, respectively, have been identified. In the present report, we examined the effect of interferon-gamma (IFN-gamma) on each type of TNF receptor. Our results indicate that IFN-gamma induces TNF receptors on both myeloid (e.g. HL-60) and epithelial cells (e.g. HeLa). Furthermore, by using antibodies specific to each type of receptor, we demonstrate that both TNF receptors are equally inducible by IFN-alpha, IFN-beta and IFN-gamma. Thus, the increase in TNF receptors by interferons may play a role in their synergistic cellular response.

Antiproliferative cytokines secreted by lymphokine-activated killer cells stimulated with tumor cells

Antiproliferative cytokine secretion by lymphokine-activated killer (LAK) cells during coculture with glioblastoma cell lines, autologous glioma cells, and nongliomatous tumor cell lines (Daudi and K562 cells) was assessed, as was the antiproliferative activity of the culture supernatants against the T98G (glioblastoma) cell line. A neutralization test using agents against interferon-gamma (IFN-gamma), tumor necrosis factor (TNF), and lymphotoxin (LT) showed that antiproliferative activity was due to IFN-gamma, but not to TNF or LT. Nongliomatous tumor cells stimulated LAK cells to secrete cytokines, but gliomatous tumor cells did not. It was found that there is a discrepancy between the LAK cell capability to lyse malignant glioma cells and the ability to secrete cytokines. This may be due to the factors secreted by glioblastoma cells.

Inhibition of tumor-induced angiogenesis by the administration of recombinant interferon-gamma followed by a synthetic lipid-A subunit analogue (GLA-60)

The effect of the administration of recombinant interferon-gamma (rIFN-gamma) and a synthetic lipid A subunit analog (GLA-60) on angiogenesis induced by B16-BL6 melanoma was examined in syngeneic C57BL/6 mice. Intravenous administration of rIFN-gamma followed by GLA-60 (referred to as rIFN-gamma/GLA-60) induced endogenous production of tumor necrosis factor (TNF). This treatment on day 3 after tumor inoculation caused a marked decrease in the number of vessels oriented towards the tumor mass (angiogenic response) and tumor size over a period of 9 days. In contrast, neither rIFN-gamma nor GLA-60 alone, nor GLA-60/rIFN-gamma (reverse sequence of administration), which is unable to induce the production of TNF in the serum, had any effect. Sera induced by the treatment with rIFN-gamma/GLA-60, and recombinant TNF, inhibited the in vitro growth of lung endothelial cells which is considered to be one of the essential events in tumor neovascularization. Multiple i.v. treatments with rIFN-gamma/GLA-60 on days 5, 8 and 11 after s.c. implantation of tumor significantly inhibited primary tumor growth by the amputation time (day 20) and lung metastasis of B16-BL6 cells on day 34, while other treatment modalities had no such effect. Our results indicate that inhibition of lung-tumor metastasis by rIFN-gamma/GLA-60 treatment may be partly due to the inhibition of tumor-associated angiogenesis.

Enhanced release of cytokines, interleukin-2 receptors, and neopterin after long-distance running

This study was designed to examine cytokine production in a group of 22 well-trained runners covering a distance of 20 km within 2 hr. After running, all participants displayed a marked granulocytosis for 7 hr. Plasma neopterin levels increased 1 hr after exercise for 24 hr. Except for interleukin-6 (IL-6), cytokines were not reliably detected in plasma but were present in urine. Already before exercise, cytokines were detected in the urine of runners when compared to sedentary controls. Directly after running, interferon-gamma and tumor necrosis factor-alpha were further elevated but rapidly declined to preexercise levels. Interleukin-1 beta and interleukin-6 increased at a slower rate after exercise but secretion into urine persisted longer until 12 and 7 hr, respectively. Interleukin-2 (IL-2) was not detected but soluble IL-2 receptors appeared in the urine directly after running. Enhanced cytokine levels were accompanied by an only low creatinin kinase increase, indicating little muscle damage. These data show that long-distance running elevates cytokine production which supports the concept that regular, but not excessive, physical exercise may be beneficial by maintaining a stimulated immune system.

Tumor necrosis factor and chemotherapeutic drugs targeted at DNA topoisomerase II for the treatment of genitourinary malignancies

Recombinant TNF as a single agent for human cancer appears to be of limited value. However, rTNF has synergistic anticancer effects when combined with chemotherapeutic drugs targeted at DNA topoisomerase II. This effect of rTNF has been observed in several in vitro and in vivo tumor models, both in animal and human studies. The mechanism of this interaction appears to involve lesions to the DNA of tumor cells mediated by inhibition of DNA topoisomerase II. The combinations of rTNF plus doxorubicin and rTNF plus etoposide administered systemically are currently under evaluation by clinical trials in patients with advanced cancers. Determination of the efficacy of such combination therapy must await the completion of phase I and II trails. Other routes of administration that might increase the local concentration of rTNF and could be combined with topoisomerase II-targeted drugs include intravesical administration and the use of tumor-infiltrating lymphocytes.

The lack of receptors for atrial natriuretic peptides on human monocytes prevents a rise of cGMP and induction of tumor necrosis factor-alpha synthesis

Freshly harvested human monocytes were shown to produce tumor necrosis factor-alpha (TNF-alpha) in response to exogenously added or sodium nitroprusside-generated cGMP. In contrast, atrial natriuretic peptide (ANP) that acts by elevating cGMP in a variety of cells, was incapable of inducing TNF-alpha synthesis. This failure was due to a lack of ANP receptors and thus, to the inability of ANP to raise cGMP in human monocytes.

Crystallization and preliminary x-ray diffraction studies of recombinant rabbit interferon-gamma

Two different crystal forms of recombinant rabbit IFN-gamma were obtained under different crystallization conditions. The first, a tetragonal form with space group P43212 or P41212, was obtained through vapor phase equilibration using the sitting drop rods technique with ammonium citrate as the major precipitating agent. The unit cell dimensions of this crystal form are a = b = 82.1 A and C = 116.3 A. These crystals diffract to 2.8 A resolution and contain a dimer in the asymmetric unit. A second crystal form was obtained by the batch method at pH 8.0 using sodium chloride as the precipitating agent. The crystals are hexagonal, space group P6122 or P6522, and with unit cell dimensions of a = b = 58.0 A and c = 169 A. This form contains monomer in the asymmetric unit and diffracts to greater than 2.7 A resolution. Both forms appear to be eminently suitable for further analyses and crystal structure solution.

Regulation of tumor necrosis factor receptor expression by acid-labile interferon-alpha from AIDS sera

High levels of an unusual acid-labile interferon (IFN) alpha in sera of patients with human immunodeficiency virus (HIV) infection are associated with disease progression to acquired immunodeficiency syndrome (AIDS). Since IFNs have been shown to enhance the cytotoxic actions of tumor necrosis factor (TNF), a potent mediator of inflammation and cachexia, a study was undertaken to investigate whether the acid-labile IFN alpha produced in AIDS can regulate TNF receptor expression. The expression of TNF receptors was determined by studying the interaction of [125I]TNF with cellular receptors. The results show the acid-labile IFN alpha present in AIDS sera is capable of inducing the expression of cellular receptors for TNF. The extent of induction of TNF receptors depends on the concentration of the acid-labile IFN alpha in the AIDS sera. There is no significant induction of TNF receptors when the AIDS sera are preneutralized with polyclonal anti-IFN alpha antibodies. It is also shown that the synthesis of TNF by peripheral blood monocytes (PBM) from patients with HIV infection is enhanced during the progression of HIV infection in vivo. Thus, the TNF system is activated in patients with HIV infection. This activation may be a contributing factor to some of the physiological disturbances including the wasting syndrome observed in AIDS.

Lymphocytes involved in cell-mediated immune responses and methods to assess cell-mediated immunity

With increasing need for the development of vaccines against many poultry diseases, it is important to understand host immune mechanisms involved in protection against diseases. Because of increasing evidence suggesting a role of cell-mediated immunity in disease resistance against many poultry disease, investigation of immune systems involved in cell-mediated immunity is crucial for the development of immunological control strategies. Recent advances in hybridoma technology and cellular immunology have facilitated the understanding of the ontogeny, structure, and function of the avian immune system. Isolation and flow cytometric analysis of single lymphoid cells now enables researchers to dissect various components of the avian immune system and to investigate the role of subpopulations of lymphocytes in disease processes. In vitro assays are used to asses the host cellular response based upon antigen-specific lymphoproliferation, specific cellular effector function, and lymphokine secretion. These various assays can be used to quantify and qualify host immune responses and to better understand host immunity.

Antiviral activity against transmissible gastroenteritis virus, and cytotoxicity, of natural porcine interferons alpha and beta

Porcine interferon (POIFN)-alpha prepared in primed peripheral blood leukocyte cultures induced with Newcastle disease virus and POIFN-beta from PK-15 cell cultures induced with polyinosinic:polycytidylic acid were partially purified by precipitation with potassium thiocyanate and anion exchange chromatography. Mean purification factors in terms of units of POIFN per mg of protein, of 37 and 12 were obtained for POIFN-alpha and POIFN-beta respectively. In yield reduction assays in swine testis and pig kidney cell cultures, POIFN-alpha and POIFN-beta had greater antiviral activity against vesicular stomatitis virus than against transmissible gastroenteritis virus (TGEV). The antiviral effects were greater at higher concentrations of interferon (IFN), and when the IFN treatments were continued postinfection. Porcine interferon-beta showed greater antiviral activity against TGEV than POIFN-alpha, but this may have been partly due to cytotoxicity. There were no major differences in the antiviral activities of crude and partially purified IFN preparations. Both types of IFN showed antiviral activity against TGEV in yield reduction assays in porcine intestinal explant and intestinal epithelial cell cultures. Crude POIFN-beta was found to be rapidly cytotoxic, especially in porcine cells, and some fractions of partially purified POIFN-beta were also cytotoxic. The cytotoxicity of POIFN-beta was partially neutralized by antibodies against human IFN-beta, but human IFN-beta was not cytotoxic for porcine or bovine cells.

Increased susceptibility of IFN-gamma-treated neuroblastoma cells to lysis by lymphokine-activated killer cells: participation of ICAM-1 induction on target cells

We have investigated the effect of interferon-gamma (IFN-gamma) treatment of neuroblastoma cells on the susceptibility to lysis by lymphokine-activated killer (LAK) cells and examined the participation of cell-adhesion molecules on the target cells in LAK cell lysis. Untreated neuroblastoma cells expressed lymphocyte-function-associated antigen 3 (LFA-3) and neural-cell-adhesion molecule (NCAM), but did not express MHC-class-I, MHC-class-II, or intercellular-adhesion molecule I (ICAM-I). IFN-gamma treatment of neuroblastoma cells induced the expression of MHC-class-I and ICAM-I antigens, but did not affect the expression of MHC-class-II, LFA-3, and NCAM. This was accompanied by an increased susceptibility to lysis by LAK cells. Anti-ICAM-I antibody inhibited partially the increased sensitivity of IFN-gamma-treated neuroblastoma cells to LAK cell lysis, and blocked completely the increase in binding of LAK cells observed after IFN-gamma treatment of the target cells. These results suggest that the increased LAK sensitivity of IFN-gamma-treated neuroblastoma cells is partially attributable to the induction of ICAM-I on neuroblastoma cells and indicate that post-binding events also play a role in the increased sensitivity to LAK cell lysis observed after IFN-gamma treatment.

Tumor necrosis factor production and receptor expression by a human malignant glioma cell line, D54-MG

Human malignant gliomas possess some of the same immune-related functions as astrocytes do. For instance, they are capable of secreting various immunoregulatory molecules and expressing HLA-DR antigens on their surface. The human malignant glioma cell line, D54-MG, was used to investigate the proliferative effects of tumor necrosis factor-alpha (TNF-alpha) and the expression of specific surface receptors for TNF-alpha. Additionally, we were interested in examining whether D54-MG cells are capable of synthesizing and secreting biologically active TNF-alpha. D54-MG cells responded in a mitogenic fashion upon incubation with TNF-alpha for 48 h under serum-free conditions. 125I-labeled TNF-alpha was used in this study to investigate the expression of receptors specific for TNF-alpha on D54-MG cells. Scatchard analysis of our receptor binding data produced curvilinear plots indicating there are two distinct receptor sites for TNF-alpha. From these data, we calculated that there are approximately 3500 high affinity and 24,666 low affinity binding sites per cell. Pretreating these cells with interferon-gamma (IFN-gamma) resulted in a 2-fold increase in the number of high affinity binding sites and a moderate increase in the number of low affinity binding sites, with no appreciable change in binding affinity (Kd) of either site. D54-MG cells were unable to constitutively secrete TNF-alpha; however, upon stimulation, these cells synthesize and secrete biologically active TNF-alpha. Polyclonal antisera reactive with human macrophage-derived TNF-alpha neutralized the cytotoxicity of D54-MG-derived TNF-alpha, demonstrating that the cytotoxic activity was in fact due to TNF-alpha. Our observations indicate that TNF-alpha could act in an autocrine fashion to induce the proliferation of this malignant glioma cell line and that TNF-alpha exerts its effect by binding to specific TNF-alpha receptors whose expression was enhanced by IFN-gamma.

Effects of murine recombinant interferon-gamma on rat liver fat storing cell proliferation, cluster formation and proteoglycan synthesis

Rat liver fat storing cells (FSC, perisinusoidal lipocytes, Ito cells) in primary culture were exposed to various concentrations of murine recombinant interferon-gamma (rIFN-gamma) in the range of 1 to 50 units/mL medium for 72 hr. FSC kept in complete medium (10% fetal calf serum) showed a dose-dependent increase of both [3H]thymidine incorporation (up to 2.3-fold) and DNA content of culture. Reverse (inhibitory) effects were obtained with cells kept under serum-reduced (0.5% fetal calf serum) conditions. The synthesis of medium proteoglycans and of total cellular protein was not affected by rIFN-gamma. By bromodeoxyuridine-staining (BrdUrd) and phase contrast microscopy it is shown that rIFN-gamma stimulates strongly the cluster growth of FSC in culture. The cluster forming cells differ in their morphology and their cytoskeleton-staining from typical FSC. They were found to be mostly desmin and alpha-actin negative or weakly positive but highly proliferative. Because no contaminating fibroblasts and other cell types were detected in any appreciable amounts in the early cultures we conclude that the clustered cells might be a rapidly proliferating subpopulation of FSC, which is promoted by rIFN-gamma.

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.

Synergistic antitumor effect of glycosylated recombinant human lymphotoxin with human interferon-gamma on lymphotoxin-sensitive human tumor

We examined the antitumor effect of glycosylated recombinant lymphotoxin (LT) in combination with human interferon-gamma (IFN-gamma) on human tumors transplanted into nude mice and compared it with that of tumor necrosis factor (TNF). The results were as follows: (i) The systemic administration of glycosylated LT combined with IFN-gamma produced a significant antitumor activity against HT-1080 fibrosarcoma, G-361 malignant melanoma, KB nasopharyngeal carcinoma, and ZR-75-1 breast carcinoma, all of which are relatively resistant to a single treatment with LT or IFN-gamma. The synergistic effect was also seen in LT-sensitive HeLa S3 tumors. The effect was observed after either i.v. or s.c. injection. (ii) In contrast, no synergistic or additive effect on HeLa S3 tumors was observed in the case of TNF combined with IFN-gamma. (iii) The serum half-life of glycosylated LT in tumor-bearing mice was about 22-fold longer than that of TNF. In conclusion, glycosylated LT, especially in combination with IFN-gamma, appears to be a potent cytokine against tumor growth in vivo compared with TNF. Its long serum half-life can result in a strong antitumor effect in combination with IFN-gamma in vivo.

Interferon-gamma overcomes glucocorticoid suppression of cachectin/tumor necrosis factor biosynthesis by murine macrophages

Glucocorticoids almost completely inhibit the synthesis by isolated macrophages of cachectin/tumor necrosis factor (TNF), a cytokine implicated as a major endogenous mediator of septic shock. Despite this in vitro effectiveness, the clinical use of glucocorticoids has failed to demonstrate any clear benefit in the treatment of septic shock. In an effort to understand what other mechanisms might play a role in the patient with sepsis, we examined the effect of interferon-gamma (IFN gamma) on the synthesis of cachectin/TNF. We show here that IFN gamma, although unable by itself to induce cachectin/TNF synthesis, enhanced the endotoxin-induced production of cachectin/TNF in vitro. Furthermore, IFN gamma overcame the inhibition of cachectin/TNF synthesis caused by the glucocorticoid, dexamethasone. These effects of IFN gamma were accounted for by increased levels of cachectin/TNF mRNA. The in vivo implications of these studies are discussed with emphasis on their relevance in human sepsis.

In vitro and in vivo anti-tumor activity of recombinant mouse tumor necrosis factor (TNF) in a mouse bladder tumor (MBT-2)

Tumor necrosis factor (TNF) has confirmed anti-tumor activity. When used in combination with interferon gamma (IFNG) or chemotherapeutic drugs targeted at DNA topoisomerase II, synergistic cytotoxicity has been observed. Investigations of the anti-tumor activity of recombinant mouse TNF in a mouse bladder tumor model (MBT-2) were performed. The cytotoxicity of TNF and low dose actinomycin-D (AMD) against MBT-2 in vitro was examined alone and following preincubation with IFNG. The activity of TNF/AMD in vivo utilizing an intravesical implantation mode (MBT-2) was also evaluated. TNF alone had no cytotoxic effect in vitro. TNF/AMD was cytotoxic for MBT-2 growth in vitro. Maximum cytotoxicity (86%) occurred at one microgram./ml. TNF/one microgram./ml. AMD with 50% cytotoxicity at .64 micrograms./ml. TNF/one/microgram./ml. AMD. A two hour preincubation with IFNG markedly increased the cytotoxicity of TNF/AMD whereas longer incubations did not enhance cytotoxic activity. TNF alone and in combination with AMD did not significantly reduce the percentage of intravesical tumor outgrowth in vivo compared to controls. This study demonstrated that TNF/AMD exhibits cytotoxicity for MBT-2 cells in vitro but is ineffective in reducing implantation of intravesical tumors in vivo. The in vitro data suggest brief exposure of MBT-2 cells to IFNG augments the subsequent anti-tumor activity of TNF/AMD.