Synergistic antiviral and antiproliferative activities of Escherichia coli-derived human alpha, beta, and gamma interferons

Biochemical and immunological aspects of COVID-19 infection and therapeutical intervention of oral low dose cytokine therapy: a systematic review

The novel coronavirus (SARS-CoV-2) pandemic has now spread to all corners of the world. It causes severe respiratory syndromes which is one of the leading causes of death. Evidence shows that the novel SARS-CoV-2 has close similarities with other coronaviruses, SARS and MERS. So, SARS-CoV-2 might use the similar mechanisms of these viruses to attack the host cells. The severity of COVID-19 is associated with various factors, one of the major reasons is immune dysregulation or immune suppression. Immunity plays a significant role in maintaining the body in a healthy condition. In order to induce a timely immune response against the invaded pathogens, both innate and adaptive immunity must be in an active state. During the viral infection, there will be an excessive generation of pro-inflammatory cytokines known as cytokine storm and also, the antiviral agents in the body gets inhibited or inactivated through viral mechanisms. Thus, this might be the reason for the transition from mild symptoms to more severe medical conditions which leads to an immediate need for the invention of a new medicine.This review aims to show the host-viral interaction along with immune response, antiviral mechanism and effectiveness of oral low dose cytokines against the virus as a therapeutic approach.

Type I IFNs: A Blessing in Disguise or Partner in Crime in MERS-CoV-, SARS-CoV-, and SARS-CoV-2-Induced Pathology and Potential Use of Type I IFNs in Synergism with IFN-γ as a Novel Antiviral Approach Against COVID-19

Since the end of 2019, the emergence of novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has accelerated the research on host immune responses toward the coronaviruses. When there is no approved drug or vaccine to use against these culprits, host immunity is the major strategy to fight such infections. Type I interferons are an integral part of the host innate immune system and define one of the first lines of innate immune defense against viral infections. The in vitro antiviral role of type I IFNs against Middle East respiratory syndrome coronavirus (MERS-CoV) and SARS-CoV (severe acute respiratory syndrome coronavirus) is well established. Moreover, the involvement of type I IFNs in disease pathology has also been reported. In this study, we have reviewed the protective and the immunopathogenic role of type I IFNs in the pathogenesis of MERS-CoV, SARS-CoV, and SARS-CoV-2. This review will also enlighten the potential implications of type I IFNs for the treatment of COVID-19 when used in combination with IFN-γ.

Pharmacokinetic and pharmacodynamic characterization of a novel formulation containing co-formulated interferons alpha-2b and gamma in healthy male volunteers

Background

More potent antitumor activity is desired in Interferon (IFN)-treated cancer patients. This could be achieved by combining IFN alpha and IFN gamma. The aim of this work was to characterize the pharmacokinetics and pharmacodynamics of a novel formulation containing a co-formulated combination of IFNs alpha-2b and gamma (CIGB-128-A).

Methods

A group of nine healthy male subjects received intramuscularly 24.5 × 10⁶ IU of CIGB-128-A. IFN concentrations were evaluated for 48 h. Serum neopterin, beta2-microglobulin (β₂M) and 2′–5′ oligoadenylate synthetase (2′–5′ OAS), classical IFN-inducible serum markers, were measured during 192 h by enzyme immunoassay and body temperature was used as pharmacodynamic variable as well.

Results

Concerning pharmacokinetics, serum IFNs’ profiles were better fitted to a mono-compartmental model with consecutive zero order and first order absorption, one bioavailability value. No interferences by simultaneous administered IFNs were observed in their typical similar systemic profiles. Neopterin and β₂M time profiles showed a delay that was efficiently linked to pharmacokinetics by means of a zero order absorption rate constant. Neopterin level was nine-fold higher than initial values, 48 h post-administration, an increment not described before. At this time, mean serum β₂M peaked around the double from baseline. Serum concentrations of the enzyme 2′–5′ OAS was still elevated on the 8 day post-injection. The formulation was well tolerated. Most frequent adverse reactions were fever, headache, arthralgia and lymphopenia, mostly mild.

Conclusions

The administration of co-formulated IFN alpha-2b and IFN gamma likely provides improved pharmacodynamic properties that may be beneficial to treat several malignancies.

Trial registration

Cuban Public Registry of Clinical Trials RPCEC00000118, May 24, 2011.

Pharmacokinetic and pharmacodynamic characterization of a new formulation containing synergistic proportions of interferons alpha-2b and gamma (HeberPAG) in patients with mycosis fungoides: an open-label trial

Background

The synergistic combination of interferon (IFN) alpha-2b and IFN gamma results in more potent in vitro biological effects mediated by both IFNs. The aim of this investigation was to evaluate by first time the pharmacokinetics and pharmacodynamics of this combination in patients with mycosis fungoides.

Methods

An exploratory, prospective, open-label clinical trial was conducted. Twelve patients, both genders, 18 to 75 years-old, with mycosis fungoides at stages IB to III, were eligible for the study. All of them received intramuscularly a single high dose (23 × 10⁶ IU) of a novel synergistic IFN mixture (HeberPAG®) for pharmacokinetic and pharmacodynamic studies. Serum IFN alpha-2b and IFN gamma concentrations were measured during 96 hours by commercial enzyme immunoassays (EIA) specific for each IFN. Other blood IFN-inducible markers and laboratory variables were used as pharmacodynamics and safety criteria.

Results

The pharmacokinetic evaluation by EIA yielded a similar pattern for both IFNs that are also in agreement with the well-known described profiles for these molecules when these are administered separately. The average values for main parameters were: Cmax: 263 and 9.3 pg/mL; Tmax: 9.5 and 6.9 h; AUC: 4483 and 87.5 pg.h/mL, half-life (t_1/2): 4.9 and 13.4 h; mean residence time (MRT): 13.9 and 13.5 h, for serum IFN alpha-2b and IFN gamma, respectively. The pharmacodynamic variables were strongly stimulated by simultaneous administration of both IFNs: serum neopterin and beta-2 microglobulin levels (β₂M), and stimulation of 2’-5’ oligoadenylate synthetase (OAS1) mRNA expression. The most encouraging data was the high increment of serum neopterin, 8.0 ng/mL at 48 h, not been described before for any unmodified or pegylated IFN. Additionally, β₂M concentration doubled the pre-dose value at 24–48 hours. For both variables the values remained clearly upper baseline levels at 96 hours.

Conclusions

HeberPAG®possesses improved pharmacodynamic properties that may be very useful in the oncologic setting. Efficacy trials can be carried out to confirm these findings.

Trial registration

Registro Público Cubano de Ensayos Clínicos RPCEC00000130

Innate and adaptive immune responses to herpes simplex virus

Immune responses against HSV-1 and HSV-2 are complex and involve a delicate interplay between innate signaling pathways and adaptive immune responses. The innate response to HSV involves the induction of type I IFN, whose role in protection against disease is well characterized in vitro and in vivo. Cell types such as NK cells and pDCs contribute to innate anti-HSV responses in vivo. Finally, the adaptive response includes both humoral and cellular components that play important roles in antiviral control and latency. This review summarizes the innate and adaptive effectors that contribute to susceptibility, immune control and pathogenesis of HSV, and highlights the delicate interplay between these two important arms of immunity.

TLR7 agonist 852A inhibition of tumor cell proliferation is dependent on plasmacytoid dendritic cells and type I IFN

Antitumor effects of the toll-like receptor 7 (TLR7) agonist, 852A, were evaluated. Supernatants from human peripheral blood mononuclear cells (PBMC) stimulated with 852A inhibited the proliferation of tumor cell lines Hs294T and 769-P but had no effect on others (786-O and Caki-1). Because addition of 852A directly to the Hs294T cells did not inhibit their proliferation, the mechanism(s) of inhibition of tumor cell proliferation was investigated. Low nanomolar concentrations of 852A stimulated the production of interferon-alpha (IFN-alpha), IFN-inducible protein-10 (IP-10), interleukin-1 receptor antagonist (IL-1Ra), monocyte chemotactic protein-1 (MCP-1), and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) from human PBMCs. Cytokines stimulated by submicromolar concentrations of 852A were sufficient to inhibit Hs294T proliferation. At higher concentrations (3-30 microM), 852A induced the production of IL-12p70, IL-18, and IFN-gamma. PBMC cultures depleted of plasmacytoid dendritic cells (pDC) did not produce IFN-alpha, and their conditioned medium did not inhibit Hs294T proliferation. Anti-IFN-alpha/beta receptor (IFNAR) and anti-IFN-alpha antibodies partially abrogated Hs294T proliferation inhibition by 852A-stimulated PBMC supernatants, whereas separate neutralization of TRAIL, tumor necrosis factor-alpha (TNF-alpha, IFN-gamma, IFN-beta, or IFN-omega had no effect. In vivo, six doses of 852A administration significantly delayed the onset of lung colonies in a B16 melanoma model. Thus, the results demonstrate that the TLR7 agonist 852A inhibits in vitro proliferation of some tumor cells in a pDC-dependent and IFN-alpha-dependent manner and can delay tumor growth in vivo.

Yellow fever virus infection in Syrian golden hamsters: relationship between cytokine expression and pathologic changes

Infection of primates by yellow fever virus (YFV) often results in severe multi-organ failure with marked histologic abnormalities. However, the role of host's immune response, particularly innate immunity, in disease process is unclear. In this study, we used a well established hamster model of yellow fever to examine the dynamic changes of cytokine expression and histopathology in the liver, spleen, kidney, and heart during the course of YFV infection. We observed that the levels of inflammatory cytokines (IFN-gamma, IL-2, TNF-alpha) in the liver were significantly reduced in the mid-stage of infection (8 days), but were elevated later (12 days). In contrast, IL-12p40 was elevated throughout the infection. The levels of IFN-gamma, IL-2, and TNF-alpha were increased in the spleen, kidney, and heart throughout the study period. For regulatory cytokines, IL-10 was significantly increased, and TGF-beta was reduced in the liver, spleen and heart in both early and mid-stages of infection, but was elevated in the kidney during the entire course of infection. In view of the pathologic changes, the observed cytokine profiles suggest that YFV has immunosuppressive effects, which contribute to liver damage in the mid-stage of infection, followed by an immunopathogenic mechanism that leads to disease progression during the late-stages of infection. Our findings support the hypothesis that organ injury by YFV is probably due to a combination of multiple factors, including direct viral injury and host innate immune responses.

Optimization of culture conditions for a synthetic gene expression in Escherichia coli using response surface methodology: The case of human interferon beta

A human interferon beta (hINF-beta) synthetic gene was optimized and expressed in Escherichia coli BL21-SI using a vector with the T7 promoter. To determine the best culture conditions such as culture medium, temperature, cell density and inducer concentration, we used the response surface methodology and a Box-Behnken design to get the highest hINF-beta production. The maximum hINF-beta production of 61 mg l(-1) was attained using minimum medium and the following predicted optimal conditions: temperature of 32.5 degrees C, cell density of 0.64, and inducer concentration of 0.30 M NaCl. This is the first report showing the successful performance of the BL21-SI system in a minimum medium. The response surface methodology is effective for the optimization of recombinant protein production using synthetic genes.

In vitro interactions between piperaquine, dihydroartemisinin, and other conventional and novel antimalarial drugs

In an in vitro assessment of antimalarial combinations, dihydroartemisinin (DHA) showed no interaction or was mildly antagonistic when combined with piperaquine, pyronaridine, or naphthoquine. Interactions between 4-aminoquinolines and related drugs were also indifferent/antagonistic. The clinical significance of mildly antagonistic DHA combinations is uncertain but may become important if parasite drug sensitivity declines.

Differential gene induction by type I and type II interferons and their combination

Type I and type II interferons (IFNs) bind to different cell surface receptors but activate overlapping signal transduction pathways. We examined the effects of a type I IFN (IFN-alphacon1) and a type II IFN (IFN-gamma1b) on gene expression in A549 cells and demonstrate that there is a common set of genes modulated by both IFNs as well as a set of genes specifically regulated by each, reflecting the activation of different signaling pathways. In particular, IFN-gamma induced many more genes of the signaling pathways, apoptosis, and cytokine interactions than did IFN-alpha. Even with genes induced by both IFNs there were distinctive quantitative differences in expression. IFN-gamma1b plays a major role in the induction and regulation of the complement pathway. Previous work has shown a synergistic antiviral and antiproliferative effect of type I and type II IFNs in cell culture and in the treatment of tumors in mice. We demonstrate that a majority of genes showed an additive effect of IFN-alphacon1 and IFN-gamma1b, but a subset of genes is synergistically induced; these include ISG20, MX2, OAS2, and other genes known to be involved in the antiviral response, TRAIL (TNFSF10) and caspases involved in apoptosis and chemokine genes RANTES, CXCL10, and CXCL11. Greater than additive transcription of some of these genes in the presence of both IFNs was confirmed by real-time kinetic RT-PCR. Elevated induction of many of these genes may be sufficient to explain the synergistic antiviral and antitumor effects of this combination of IFNs in vivo.

Transient inhibition of Th1-type cytokine production by CD4 T cells in hepatitis B core antigen immunized mice is mediated by regulatory T cells

The non-cytopathic hepatitis B virus (HBV) can induce chronic infections characterized by weak and limited T cell responses against the virus. The factors contributing to the failure to clear HBV and subsequent development of chronic HBV infections are not clearly understood, but a strong interferon-gamma (IFN-gamma) response by CD4+ T cells against the nucleocapsid hepatitis B core antigen (HBcAg) of the virus appears to be important for viral clearance. The present study documents depressed numbers of CD4+ T cells secreting IFN-gamma and interleukin-2 (IL-2) in enzyme-linked immunospot assay (ELISPOT) assays restimulated for 24 hr with antigen following both primary and secondary immunizations of mice with recombinant hepatitis B core antigen (rHBcAg). The kinetics of these responses showed that the depression occurred following a peak response and lasted approximately 2 weeks before returning to the previous peak levels. The depression was abrogated by depletion of CD25+ cells prior to culture in the ELISPOT assay, suggesting inhibition by regulatory T cells. This inhibition of IFN-gamma and IL-2 production was also reversed by in vitro restimulation of the test cells for 48 hr rather than 24 hr in the assay. No such transient, reversible inhibition was detected in the production of IL-5, a Th2-type cytokine. The inhibition in cytokine production did not appear to correlate with the number of antibody-secreting cells or the isotypes produced. This delay by regulatory T cells of Th1-type cytokine production could contribute to viral persistence in chronic HBV infection by interfering with the critical role IFN-gamma plays in protection against viral infections.

Mathematical analysis demonstrates that interferons-beta and -gamma interact in a multiplicative manner to disrupt herpes simplex virus replication

Several studies suggest that the innate interferons (IFNs), IFN-alpha and IFN-beta, can act in concert with IFN-gamma to synergistically inhibit the replication of cytomegalovirus and herpes simplex virus type 1 (HSV-1). The significance of this observation is not yet agreed upon in large part because the nature and magnitude of the interaction between IFN-alpha/beta and IFN-gamma is not well defined. In the current study, we resolve this issue by demonstrating three points. First, the hyperbolic tangent function, tanh (x), can be used to describe the individual effects of IFN-beta or IFN-gamma on HSV-1 replication over a 320,000-fold range of IFN concentration. Second, pharmacological methods prove that IFN-beta and IFN-gamma interact in a greater-than-additive manner to inhibit HSV-1 replication. Finally, the potency with which combinations of IFN-beta and IFN-gamma inhibit HSV-1 replication is accurately predicted by multiplying the individual inhibitory effects of each cytokine. Thus, IFN-beta and IFN-gamma interact in a multiplicative manner. We infer that a primary antiviral function of IFN-gamma lies in its capacity to multiply the potency with which IFN-alpha/beta restricts HSV-1 replication in vivo. This hypothesis has important ramifications for understanding how T lymphocyte-secreted cytokines such as IFN-gamma can force herpesviruses into a latent state without destroying the neurons or leukocytes that continue to harbor these viral infections for the lifetime of the host.

Identification of proteins regulated by interferon-? in resistant and sensitive malignant melanoma cell lines

Treatment of patients with malignant melanoma with interferon-alpha achieves a response in a small but significant subset of patients. Currently, although much is known about interferon biology, little is known about either the particular mechanisms of interferon-alpha activity that are crucial for response or why only some patients respond to interferon-alpha therapy. Two melanoma cell lines (MeWo and MM418) that are known to differ in their response to the antiproliferative activity of interferon-alpha, have been used as a model system to investigate interferon-alpha action. Using a proteomics approach based on two-dimensional polyacrylamide gel electrophoresis and mass spectrometry, several proteins induced in response to interferon-alpha have been identified. These include a number of gene products previously known to be type I interferon responsive (tryptophanyl tRNA synthetase, leucine aminopeptidase, ubiquitin cross-reactive protein, gelsolin, FUSE binding protein 2 and hPNPase) as well as a number of proteins not previously reported to be induced by type I interferon (cathepsin B, proteasomal activator 28alpha and alpha-SNAP). Although the proteins upregulated by interferon-alpha were common between the cell lines when examined at the level of Western blotting, the disparity in the basal level of cathepsin B was striking, raising the possibility that the higher level in MM418 may contribute to the sensitivity of this cell line to interferon-alpha treatment.

Increased Sensitivity of Sars-Coronavirus to a Combination of Human Type I and Type II Interferons

There is currently an urgent need to identify effective antiviral agents that will prevent and treat severe acute respiratory syndrome coronavirus (SARS-CoV) infection. In this study, we have investigated and compared the antiviral effect of different interferons (IFNs) on SARS-CoV replication in the epithelial kidney monkey Vero cell line. The results showed that SARS-CoV grown in Vero cells is moderately sensitive to IFN-β and only weakly sensitive to IFN-α and IFN-γ, in comparison to other IFN-sensitive viruses, such as those for encephalomyocarditis, vesicular stomatitis and Newcastle disease. Simultaneous incubation of Vero cells with IFN-β and IFN-γ indicated that they may act synergistically against SARS-CoV replication. The IFN-induced MxA protein was detected in the IFN-treated Vero cells. The data, however, suggest that the antiviral activity of IFN against SARS-CoV virus is independent of MxA expression.

In vitro antimalarial activity of retinoids and the influence of selective retinoic acid receptor antagonists

Retinol (vitamin A alcohol) may have a beneficial role in the host response to malaria in humans and previously published data have suggested that it has a direct inhibitory effect on the growth of Plasmodium falciparum in vitro. To further investigate the role of retinoids as potential antimalarial agents, we assessed the effect of all-trans-retinoic acid (RA), 9-cis-RA and 13-cis-RA, as well as retinol itself and its ester, retinyl palmitate, on 3H-hypoxanthine uptake by the laboratory-adapted strains of P. falciparum 3D7 and K1. In addition, we examined the influence of three specific RA receptor antagonists, ER 27191, Ro 415253 and AGN 194301, on retinoid-induced growth inhibition of 3D7. All-trans-RA, 9-cis-RA and 13-cis-RA in concentrations ranging from 1 x 10(-4) to 5 x 10(-10) M each had antimalarial activity, but at IC50 values (5.9 x 10(-5) to 7.9 x 10(-5) M) that were less than those of retinol (2.5 x 10(-5) to 3.2 x 10(-5) M). Retinyl palmitate had minimal effect on 3H-hypoxanthine uptake. Each of the three specific antagonists inhibited growth of 3D7 (IC50 range 1.2 x 10(-5) to 3.0 x 10(-5) M) but, in isobolographic analysis, were antagonistic to retinol (dose factor potentiation, DFP 0.46-0.79) and, in the case of Ro 415253, to all-trans-RA (DFP=0.39). Although we did not attempt to quantify losses of retinoids from the system, these data suggest that retinol has greater antimalarial activity than its RA metabolites and especially retinyl palmitate. The specific RA receptor antagonists showed paradoxical antimalarial activity but consistently antagonised the effect of retinol and all-trans-RA in isobolographic experiments. We conclude that RA metabolites may be less suitable than retinol per se as antimalarial agents and that P. falciparum might possess or acquire a RA receptor-like moiety.

The JAK/STAT pathway is not sufficient to sustain the antiproliferative response in an interferon-resistant human melanoma cell line

The mechanism of resistance of malignant melanoma to treatment with interferon-alpha is unknown, and currently there is no reliable method of predicting response. Signalling via the JAK/STAT pathway is known to mediate many interferon-regulated events and has been implicated in mediating the antiproliferative response. The objective of this study was to determine whether defects in JAK/STAT signalling may be responsible for interferon resistance. The in vitro response to interferon was determined in a panel of established melanoma cell lines, and the components and functioning of the JAK/STAT pathway were examined in sensitive and resistant cell lines. Two melanoma cell lines, characterized as sensitive (MM418) and resistant (MeWo) to the antiproliferative effect of interferon, were both shown by Western blotting to possess all the protein components of the JAK/STAT pathway, and were shown to be capable of producing functional transcription factors using an electrophoretic mobility shift assay and a ribonuclease protection assay of known interferon-induced genes. In addition, both cell lines had intact antiviral and HLA upregulation responses. These data suggest that there is no defect in the JAK/STAT pathway per se in the MeWo cell line, and that the substantial resistance to interferon must be mediated through components either downstream or additional to this signalling pathway. Others have shown JAK/STAT defects to be responsible for interferon resistance in some melanoma cell lines. However, our results highlight the likely heterogeneity in the mechanisms leading to interferon resistance both in cell lines and tumours, and suggest that a clinical assay based on analysis of components of the JAK/STAT pathway may have only limited use as a predictor of interferon response.

Alpha/Beta interferon and gamma interferon synergize to inhibit the replication of herpes simplex virus type 1

In vivo evidence suggests that T-cell-derived gamma interferon (IFN-gamma) can directly inhibit the replication of herpes simplex virus type 1 (HSV-1). However, IFN-gamma is a weak inhibitor of HSV-1 replication in vitro. We have found that IFN-gamma synergizes with the innate IFNs (IFN-alpha and -beta) to potently inhibit HSV-1 replication in vitro and in vivo. Treatment of Vero cells with either IFN-beta or IFN-gamma inhibits HSV-1 replication by <20-fold, whereas treatment with both IFN-beta and IFN-gamma inhibits HSV-1 replication by approximately 1,000-fold. Treatment with IFN-beta and IFN-gamma does not prevent HSV-1 entry into Vero cells, and the inhibitory effect can be overcome by increasing the multiplicity of HSV-1 infection. The capacity of IFN-beta and IFN-gamma to synergistically inhibit HSV-1 replication is not virus strain specific and has been observed in three different cell types. For two of the three virus strains tested, IFN-beta and IFN-gamma inhibit HSV-1 replication with a potency that approaches that achieved by a high dose of acyclovir. Pretreatment of mouse eyes with IFN-beta and IFN-gamma reduces HSV-1 replication to nearly undetectable levels, prevents the development of disease, and reduces the latent HSV-1 genome load per trigeminal ganglion by approximately 200-fold. Thus, simultaneous activation of IFN-alpha/beta receptors and IFN-gamma receptors appears to render cells highly resistant to the replication of HSV-1. Because IFN-alpha or IFN-beta is produced by most cells as an innate response to virus infection, the results imply that IFN-gamma secreted by T cells may provide a critical second signal that potently inhibits HSV-1 replication in vivo.

Tissue selectivity of interferon-stimulated gene expression in mice infected with Dam(+) versus Dam(-) Salmonella enterica serovar Typhimurium strains

The host interferon (IFN) system plays an important role in protection against microbial infections. Salmonella enterica serovar Typhimurium is highly virulent in the mouse model, whereas mutants that lack DNA adenine methylase (Dam(-)) are highly attenuated and elicit fully protective immune responses against murine typhoid fever. We examined the expression of IFN-responsive genes in several mouse tissues following infection with Dam(+) or Dam(-) Salmonella. Infection of mice with Dam(+) Salmonella resulted in the induction of host genes known to be indicators of IFN bioactivity and regulated by either IFN-alpha/beta (Mx1) or IFN-gamma (class II transactivator protein [CIITA] and inducible nitric oxide synthase [iNOS]) or by both IFN-alpha/beta and IFN-gamma (RNA-specific adenosine deaminase [ADAR1] and RNA-dependent protein kinase [PKR]) in a tissue-specific manner compared to uninfected animals. Since the Mx1 promoter is IFN-alpha/beta specific and the Mx1 gene is not inducible directly by IFN-gamma, these data suggest a role of IFN-alpha/beta in the host response to Salmonella infection. Mice infected with Dam(-) Salmonella showed reduced expression of the same set of IFN-stimulated genes (ISGs) as that observed after infection with wild-type Salmonella. The reduced capacity to induce ISGs persisted in Dam(-)-vaccinated mice after challenge with the virulent (Dam(+)) strain. Finally, although no Dam(-) organisms were recovered from the liver or spleen after oral infection of mice, ADAR, PKR, Mx, and CIITA expression levels were elevated in these tissues relative to those in uninfected mice, suggestive of the distant action of a signaling molecule(s) in the activation of ISG expression.

Persistent Ross River virus infection of murine macrophages: an in vitro model for the study of viral relapse and immune modulation during long-term infection

A clinical feature of Ross River virus disease (RRVD) is the periodic relapse of symptoms months after the initial onset of disease. The underlying mechanisms responsible for this relapse have not been determined. In a long-term (148 days) in vitro study of persistently infected murine macrophages we established that RRV infection periodically fell to undetectable biological levels that required genetic detection. However, the virus concentration spontaneously relapsed to biologically detectable levels that corresponded with enhanced viral mRNA expression, cellular detachment, and cytopathic effect. By altering the cell culture conditions we found that relapse could also be induced. We propose that the periodic relapse of symptoms in RRVD may be associated with spontaneous or stress-induced increases in RRV within persistently infected macrophages. This study also established that RRV enhanced macrophage phagocytic activity and dysregulated the immunoregulatory molecules CD80, IFN-gamma, and TNF-alpha that may facilitate persistence of RRV and avoidance of immune responses.

Immunization onto bare skin with synthetic peptides: immunomodulation with a CpG-containing oligodeoxynucleotide and effective priming of influenza virus-specific CD4+ T cells

Exploiting the immune system of the skin for vaccine administration offers an attractive alternative to the currently used invasive immunization procedures. In this study we report that a synthetic peptide representing a T-helper (Th) epitope from influenza virus haemagglutinin (aa 307--319) can be an effective immunogen when coapplied with cholera toxin (CT) onto bare skin. Proliferation of both peptide- and influenza virus-specific CD4+ T cells was measured in lymphocyte cultures from spleens and regional lymph nodes. The presence of the CpG oligodeoxynucleotide 1826 in the peptide/CT formulation, enhanced the proliferation of peptide- and virus-specific T cells as measured by the conventional [(3)H]thymidine uptake and interleukin (IL)-2 assays. Furthermore, the bias towards Th2-type of responses stimulated by CT was shifted towards Th1 as demonstrated (i) by the increase of interferon-gamma and decrease of IL-4 cytokine levels measured in culture supernatants, (ii) by the predominance of IG2a anti-CT antibodies in the serum, and (iii) by the down-regulation of total serum IgE antibody levels. These findings demonstrate the potential of the bare skin as a non-invasive route for administration of small molecular size peptide antigens. Furthermore, with the selection and combination of the appropriate type of adjuvants, immune responses can be modulated towards the desired type of Th phenotype.

CD4(+) T cell subsets during virus infection. Protective capacity depends on effector cytokine secretion and on migratory capability

To analyze the antiviral protective capacities of CD4(+) T helper (Th) cell subsets, we used transgenic T cells expressing an I-A(b)-restricted T cell receptor specific for an epitope of vesicular stomatitis virus glycoprotein (VSV-G). After polarization into Th1 or Th2 effectors and adoptive transfer into T cell-deficient recipients, protective capacities were assessed after infection with different types of viruses expressing the VSV-G. Both Th1 and Th2 CD4(+) T cells could transfer protection against systemic VSV infection, by stimulating the production of neutralizing immunoglobulin G antibodies. However, only Th1 CD4(+) T cells were able to mediate protection against infection with recombinant vaccinia virus expressing the VSV-G (Vacc-IND-G). Similarly, only Th1 CD4(+) T cells were able to rapidly eradicate Vacc-IND-G from peripheral organs, to mediate delayed-type hypersensitivity responses against VSV-G and to protect against lethal intranasal infection with VSV. Protective capacity correlated with the ability of Th1 CD4(+) T cells to rapidly migrate to peripheral inflammatory sites in vivo and to respond to inflammatory chemokines that were induced after virus infection of peripheral tissues. Therefore, the antiviral protective capacity of a given CD4(+) T cell is governed by the effector cytokines it produces and by its migratory capability.

Preliminary results of the alternating administration of natural interferon-alpha and recombinant interferon-gamma for metastatic renal cell carcinoma

OBJECTIVE

To evaluate the efficacy and toxicity of the alternating administration of natural (n) interferon (IFN)-alpha and recombinant (r) IFN-gamma for metastatic RCC.

PATIENTS AND METHODS

The study comprised 24 patients (median age 60 years, range 42-77), 20 of whom were evaluable for response and all 24 evaluable for toxicity. Initially, nIFN-alpha was administered subcutaneously on days 1 and 3, and rIFN-gamma on day 2, for 1-2 weeks in the evening or at night, both at doses of 3 MU. If this regimen was tolerated, nIFN-alpha and rIFN-gamma were administered at the same doses on days 1, 3 and 5, and on days 2 and 4, respectively.

RESULTS

There were three complete remissions and two partial remissions, giving a total response rate of 25%. All responders (complete plus partial remission) had undergone nephrectomy. Multiple lung metastases completely disappeared from four responders. The median and maximum time to remission in the responders were 2 and 7 months, respectively. The survival time of the responders was significantly longer than that of those not responding (stable and progressive disease, P=0.0202). Toxicities were mostly limited to WHO grades 1 and 2, with grade 3 leucopenia and grade 4 hepatic dysfunction in only one patient each. These toxicities were transient and there were no treatment-related deaths.

CONCLUSION

The alternating administration of nIFN-alpha and rIFN-gamma is an effective treatment for metastatic RCC. This treatment is particularly suitable for patients who have undergone nephrectomy and have lung metastases.

Qualitative and Quantitative Requirements for CD4+ T Cell-Mediated Antiviral Protection

CD4+ Th cells deliver the cognate and cytokine signals that promote the production of protective virus-neutralizing IgG by specific B cells and are also able to mediate direct antiviral effector functions. To quantitatively and qualitatively analyze the antiviral functions of CD4+ Th cells, we generated transgenic mice (tg7) expressing an MHC class II (I-Ab)-restricted TCR specific for a peptide derived from the glycoprotein (G) of vesicular stomatitis virus (VSV). The elevated precursor frequency of naive VSV-specific Th cells in tg7 mice led to a markedly accelerated and enhanced class switching to virus-neutralizing IgG after immunization with inactivated VSV. Furthermore, in contrast to nontransgenic controls, tg7 mice rapidly cleared a recombinant vaccinia virus expressing the VSV-G (Vacc-IND-G) from peripheral organs. By adoptive transfer of naive tg7 CD4+ T cells into T cell-deficient recipients, we found that 105 transferred CD4+ T cells were sufficient to induce isotype switching after challenge with a suboptimal dose of inactivated VSV. In contrast, naive transgenic CD4+ T cells were unable to adoptively confer protection against peripheral infection with Vacc-IND-G. However, tg7 CD4+ T cells that had been primed in vitro with VSV-G peptide were able to adoptively transfer protection against Vacc-IND-G. These results demonstrate that the antiviral properties of CD4+ T cells are governed by the differentiation status of the CD4+ T cell and by the type of effector response required for virus elimination.

A randomized phase II study comparing four different interferon therapies in patients with recalcitrant condylomata acuminata

BACKGROUND

Interferon (IFN) alpha and IFN gamma have synergistic in vitro and in vivo effects and have each been used in the treatment of anogenital condylomata acuminata.

STUDY GOALS

To compare the efficacy and safety of regional 3 x 10(6) U IFN alpha (Group A), 3 x 10(6) U IFN gamma (Group B), 1.5 x 10(6) U IFN alpha plus 1.5 x 10(6) U IFN gamma (Group C), and 3 x 10(6) U IFN alpha plus 1.5 x 10(6) U IFN gamma (Group D) in the treatment of recalcitrant anogenital condylomata acuminata.

STUDY DESIGN

Six-week courses of regional IFNs were administered in a randomized, double-blind, multicenter study. Response was assessed as change in the total area affected by condylomata.

RESULTS

The treatments of Groups A, B, and C were similarly effective (complete response in 13.6%, 18.5%, and 16.0%, respectively). Group D had the lowest rate of complete response (3.8%), but this combination was the most effective when partial and complete responses were combined (73.0%).

CONCLUSION

Regional IFN is a moderately effective and safe treatment in patients with recalcitrant anogenital condylomata acuminata. Combinations of IFNs alpha and gamma were not superior to IFN monotherapy.

IFN-γ Priming Up-Regulates IFN-Stimulated Gene Factor 3 (ISGF3) Components, Augmenting Responsiveness of IFN-Resistant Melanoma Cells to Type I IFNs

IFN-stimulated gene factor 3 (ISGF3) mediates transcriptional activation of IFN-sensitive genes (ISGs). The component subunits of ISGF3, STAT1αβ, STAT2, and p48-ISGF3γ, are tyrosine phosphorylated before their assembly into a complex. Subsequently, the ISGF3 complex is translocated to the nucleus. We have recently established that the responsiveness of human melanoma cell lines to type I IFNs correlates directly with their intracellular levels of ISGF3 components, particularly STAT1. In the present study, we show that pretreating IFN-resistant melanoma cell lines with IFN-γ (IFN-γ priming) before stimulation with type I IFN also results in increased levels of ISGF3 components and enhanced DNA-binding activation of ISGF3. In addition, IFN-γ priming of IFN-resistant melanoma cell lines increased expression of type I IFN-induced ISG products, including ISG54, 2′-5′-oligoadenylate synthase, HLA class I, B7-1, and ICAM-1 Ags. Furthermore, IFN-γ priming enhanced the antiviral effect of IFN-β on the IFN-resistant melanoma cell line, MM96. These results support a role for IFN-γ priming in up-regulating ISGF3, thereby augmenting the responsiveness of IFN-resistant melanoma cell lines to type I IFN and providing a molecular basis and justification for using sequential IFN therapy, as proposed by others, to enhance the use of IFNs in the treatment of melanoma.

Chicken interferon types I and II enhance synergistically the antiviral state and nitric oxide secretion

This report shows that chicken type I and type II interferons (IFNs), like their mammalian counterparts, act synergistically such that a mixture of the two has much greater activity than that expected from the separate contribution of each type. The degree of antiviral synergy was measured by virus plaque reduction and cytopathic effect (CPE) inhibition in both primary and secondary chicken embryo cell cultures. Mixtures of the two Ch-IFNs produced antiviral effects 3-10 times greater than that expected from strict additivity of each IFN acting alone. At high concentrations of IFN mixtures there was a qualitative shift to an exponential IFN action does-response curve that revealed synergistic effects greater than 100-fold. Synergy resulted even with mixtures containing less than 1 U/ml of either type of Ch-IFN. The antiviral effects developed more rapidly with mixtures than when type I or II Ch-IFN was used alone. Mixtures of the two types of Ch-IFN synergistically potentiated nitric oxide secretion in cells of the HD11 chicken macrophage line. Molecular mechanisms are cited that may account for synergy between type I and type II IFNs, and speculation is offered on the epidemiologic and therapeutic implications of synergy in vivo.

Combined effects of interferon-alpha and acyclovir on herpes simplex virus type 1 DNA polymerase and alkaline DNase

Treatment of cells with combinations of human interferon-alpha (IFN-alpha) and the nucleoside analog, acyclovir (ACV), leads to the synergistic inhibition of herpes simplex virus type 1 (HSV-1) replication. We have examined the effect of these agents on the replication of HSV-1 DNA and the synthesis of early viral enzymes to understand the mechanism(s) responsible for this synergistic activity. Combination treatment with 100 IU/ml IFN-alpha and 5 microM ACV led to HSV-1 DNA levels more than 8-fold lower than in cells treated with ACV alone, while IFN-alpha treatment alone had no detectable effect on viral DNA synthesis. Steady state levels of DNA polymerase were reduced approximately 50% by IFN-alpha and 25% by ACV, but combination treatment did not decrease enzyme levels to an extent greater than the sum of these effects. In contrast, the activity of another early viral enzyme, alkaline DNase, was reduced less than 20% by IFN-alpha alone or combination treatment and was unaffected by ACV treatment. No decrease in the level of mRNA encoding either enzyme was detected in IFN-alpha-treated cells although ACV treatment reduced polymerase mRNA levels. These studies suggest that the synergistic anti-HSV activities of IFN-alpha with ACV could be mediated, in part, through some post-transcriptional mechanism induced by IFN-alpha treatment, leading to the reduction in production of viral early enzymes, especially DNA polymerase.

Cytokines and immunity to viral infections

In this review, we discuss two broad approaches we have taken to study the role of cytokines and chemokines in antiviral immunity. Firstly, recombinant vaccinia viruses were engineered to express genes encoding cytokines and chemokines of interest. Potent antiviral activity was mediated by many of these encoded factors, including IL-2, IL-12, IFN-gamma, TNF-alpha, CD40L, Mig and Crg-2. In some cases, host defense mechanisms were induced (IL-2, IL-12, Mig and Crg-2), whilst for others, a direct antiviral effect was demonstrated (IFN-gamma, TNF-alpha and CD40L). In sharp contrast, vector-directed expression of IL-4, a type 2 factor, greatly increased virus virulence, due to a downregulation of host type 1 immune responses. Our second experimental approach involved the use of strains of mice deficient for the production of particular cytokines or their receptors, often in combination with our engineered viruses. Mice deficient in either IFN-gamma, IFN-gamma R, IFN-alpha/beta R, TNFRs, CD40 or IL-6 were, in general, highly susceptible to poxvirus infection. Surprisingly, not only the TNFR1, but also the TNFR2, was able to mediate the antiviral effects of TNF-alpha in vivo, whilst the antiviral activity observed following CD40-CD40L interaction is a newly defined function which may involve apoptosis of infected cells. Through the use of perforin-deficient mice, we were able to demonstrate a requirement for this molecule in the clearance of some viruses, such as ectromelia virus, whilst for others, such as vaccinia virus, perforin was less important but IFN-gamma was essential.

Interferon-gamma enhances resolution of herpes simplex virus type 2 infection of the murine genital tract

The requirement for interferon-gamma (IFN gamma) in resolution of an HSV-2 vaginal infection and the cellular sources of this cytokine in the vaginal mucosa were assessed. IFN gamma levels in vaginal secretions peaked on Days 2 and 5 following HSV-2 inoculation. Natural killer (NK) cell depletion greatly diminished the early production of IFN gamma but had no significant effect on the rate of virus clearance. CD4+ T cells were primarily responsible for the second peak of IFN gamma levels and neutralization of this IFN gamma beginning 3 days after virus inoculation delayed, but did not prevent, virus clearance from the vagina. HSV-2 persisted in mice depleted of both CD4+ and CD8+ T cells while clearance was delayed in CD4+, but not CD8+ T cell-depleted mice, demonstrating the T cell dependence and predominant role of CD4+ T cells in resolution of the infection. Together, these data suggest that IFN gamma is not essential for virus clearance but plays an important role in enhancing T cell-mediated clearance mechanisms. The implication of these results is that IFN gamma produced locally in the genital tract enhances virus clearance and may ultimately be important for reducing the amount of virus available to infect sensory ganglia.

Counteracting effect of IFN-beta on IFN-gamma-induced proliferation of human astrocytes in culture

Recent clinical trials have shown that interferon beta (IFN-beta) is effective in reducing exacerbations in relapsing-remitting MS, while interferon gamma (IFN-gamma) precipitates the relapses. To investigate mechanisms underlying the beneficial effects of IFN-beta and the detrimental effects of IFN-gamma in MS, cell growth-regulatory effects of IFNs were examined in astrocyte-enriched cultures isolated from fetal brains of 12-20 weeks' gestation. Treatment with IFN-gamma (50 or 500 IU ml-1) stimulated significantly the proliferation of astrocytes in 6 out of 9 culture series examined, while IFN-beta (50 or 500 IU ml-1) inhibited the astrocytic proliferation in 3 out of 9 cultures, and IFN-alpha (50 or 500 IU ml-1) did not affect the proliferation IFN-beta and to a lesser degree IFN-alpha reduced the astrocytic proliferation induced by IFN-gamma-treatment in 8 out of 9 culture series. The counteracting effect of IFN-alpha/IFN-beta against IFN-gamma-induced astrocytic proliferation was verified by the DNA content distribution analysis of propidium iodide-labeled cells. The antagonistic effect of IFN-alpha/IFN-beta on the growth-promoting activity of IFN-gamma in cultured human astrocytes suggests that interferons serve as growth regulators of astrocytes at sites of reactive gliosis lesions of MS.

Stimulation of natural interferon-alpha/beta-producing cells by Staphylococcus aureus

Human peripheral blood mononuclear cells (PBMCs) produced high levels of antiviral activity, as determined by bioassay, when stimulated by Staphylococcus aureus Cowan I (SAC) and E. coli. Specific immunoassays demonstrated the presence of both IFN-alpha and gamma and, for SAC, also low levels of IFN-beta. The frequencies of SAC-induced IF N-alpha-producing cells (IPCs) were up to 1-2 per 10(3) PBMCs. These IPCs expressed the HLA-DR and CD4 antigens but not CD3, CD14, or CD19, thus resembling the natural IFN-alpha-producing cells (NIPC). The SAC was more efficient as IFN inducer when heat killed than when streptomycin inhibited. The SAC was inhibitory to virally induced IFN-alpha responses, in particular when streptomycin inhibited. Both pronase treatment and mechanical disruption of SAC cells abolished their capacity to induce IFN-alpha production. Staphylococcal strains lacking or expressing low levels of protein A (SpA) showed a decreased ability to induce IFN-alpha production. However, purified SpA did not itself induce IFN-alpha. Possibly, SpA together with other bacterial surface proteins is important for the capacity of SAC to induce IFN-alpha production in NIPC.

Gamma interferon down-regulates glucocorticoid receptor expression and attenuates hormone action in a human osteosarcoma cell line

The effect of gamma interferon (IFN) on glucocorticoid receptor (GR) expression was studied in HOS-8603 cells, a human osteogenic sarcoma cell line. Treatment of HOS-8603 cells with IFN resulted in down-regulation of GR number, with no change in the binding affinity for glucocorticoids. The maximum decrease in receptor binding was evident at 10 IU/ml IFN concentration. Time-course studies revealed that the effect reached a maximum at 36 h treatments. To clarify the molecular basis for the down-regulation of GR by IFN, change in GR mRNA levels was further investigated by RNA blot hybridization analysis. It was found that there also existed a time-dependent decrease in GR mRNA levels in HOS-8603 cells after treatment with IFN. In the presence of IFN, the inhibitory effect of glucorticoids on HOS-8603 cell proliferation was blunted. Moreover, the induction of alkaline phosphatase (AKP) activity by glucocorticoids was attenuated in response to IFN treatment. These data suggest that IFN may influence GR activity which at least partially occurs at mRNA levels, and that the decrease in receptor activity in HOS-8603 cells parallels with the decrease in glucocorticoid-mediated functional responses.

Interferon-alpha therapy for chronic myelogenous leukemia

PURPOSE

To provide a status report on the use of interferon (IFN)-alpha in patients with chronic myelogenous leukemia (CML).

DATA SOURCES

Data on IFN-alpha therapy for CML collected from published articles identified in a MEDLINE computer search.

RESULTS

Previously untreated patients with low-risk factors and early-stage disease consistently had the best results in clinical trials. A dose response was seen, with patients treated with dosages of 5 million units (MU)/m2 per day showing the greatest incidence of cytogenetic remissions. In addition, randomized trials showed a survival advantage for IFN-alpha-treated patients. In studies comparing IFN-alpha therapy to chemotherapy, IFN-alpha produced significantly more major and durable cytogenetic responses than chemotherapy did. In studies combining IFN-alpha and chemotherapy, patients had significantly more cytogenetic responses, although more patient accrual and follow-up data are needed to offer conclusive statements concerning durability of response. IFN-alpha also showed activity in maintaining remissions after both chemotherapy and bone marrow transplantation.

CONCLUSIONS

IFN-alpha has significant activity in patients with CML, with best results at dosages of 5 MU/m2 per day. At these dosages, in patients with early-stage, Philadelphia+ CML, hematologic response rates of 70% to 80% and cytogenetic response rates of 50% (approximately 20% of which were complete) are seen. One randomized trial shows a survival advantage with cytogenetic response in IFN-alpha-treated patients, and this advantage appears to be unrelated to the degree of that response. These questions remain under study.

Assessment of the therapeutic potential of cytokines, cytotoxic drugs and effector cell populations for the treatment of multiple myeloma using the 5T33 murine myeloma model

The therapeutic potential of six cytokines, eight cytotoxic drugs and two effector cell populations for the treatment of multiple myeloma was assessed in vitro using the 5T33 murine myeloma model. The efficacy of combination IFN-alpha and melphalan therapy was also evaluated in vitro and in vivo. Of the cytokines tested in vitro using the MTT assay, only IFN-alpha demonstrated significant inhibition of myeloma cell growth at non-toxic concentrations (ED50 = 1508.3 +/- 181.3 U/mL and 2617.9 +/- 334.0 U/mL for murine IFN-alpha [mIFN-alpha] and human IFN-alpha hybrid B/D [hIFN-alpha B/D], respectively). The ED50 for the eight cytotoxic drugs tested ranged from 2.3 x 10(-9) to 4.3 x 10(-13) mol/L and all were within the therapeutic range for humans. Combination hIFN-alpha B/D and melphalan were found to be additive in their inhibitory effects on myeloma cell growth in vitro and this finding was confirmed in vivo in C57BL/KaLwRij mice bearing disseminated 5T33 myeloma. Control animals demonstrated a median survival duration of 25.3 days whereas hIFN-alpha B/D or melphalan treatment alone increased survival to 30.5 and 33.3 days, respectively (P < 0.001). Combination IFN-alpha/melphalan therapy increased median survival duration to 38.5 days (P < 0.001) which was also significantly greater than that obtained with single agent therapy (P < 0.01). The murine myeloma cells were found to be resistant to NK cell lysis but susceptible to lysis by LAK cells (49.3 +/- 6.3% lysis at an effector to target ratio of 100:1).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of transforming growth factor-beta on bone marrow macrophage Ia expression induced by cytokines

The initiation of the immune response is regulated, in part, by the effect of cytokines on the level of expression of major histocompatibility complex (MHC) class II antigens on antigen-presenting cells (APC). The expression of class II antigens on B cell and macrophage APC is induced by IFN-gamma and IL-4, and GM-CSF induces class II expression on macrophages (M phi). Our results show that transforming growth factor-beta (TGF-beta) inhibits IL-4- and GM-CSF-induced Ia gene expression on bone marrow macrophages but enhances IFN-gamma-induced gene expression. Nuclear run-on experiments demonstrated that the inhibitory effects of TGF-beta on GM-CSF- and IL-4-induced Ia antigen expression were primarily posttranscriptional and augmentation of IFN-gamma by TGF-beta was largely transcriptionally regulated.

Interferon alfa and gamma inhibit proliferation and collagen synthesis of human Ito cells in culture

During the course of ongoing liver fibrogenesis, Ito cells acquire myofibroblastic features, proliferate, and synthesize increased amounts of extracellular matrix components. Interferon (IFN) alfa and IFN gamma have been shown to elicit antiproliferative and/or antifibrogenic effects in various cell cultures of mesenchymal origin. The aim of this study was to investigate the effects of IFN-alpha and IFN-gamma on cultured human myofibroblastic Ito cells (MFBIC) proliferation and collagen synthesis and secretion. Serum-stimulated incorporation of [3H]-thymidine into DNA of MFBIC was dose-dependently decreased by both cytokines. IFN-alpha (10(4) U/mL) and IFN-gamma (10(3) U/mL) decreased DNA synthesis by 69% and 66%, respectively. Inhibition of cell proliferation was confirmed by cell counting. Similar results were observed when cell growth was stimulated with platelet-derived growth factor (PDGF-BB, PDGF-AA) or transforming growth factor (TGF)-beta 1. Collagen secretion per cell was inhibited by both cytokines, as assessed by [3H]-hydroxyproline incorporation. After a 6-day treatment, IFN-gamma showed a greater potency than IFN-alpha in inhibiting secretion of newly synthetized collagen (41% and 4% of control in the presence of 10(2) U/mL of IFN-gamma and 10(4) U/mL of IFN-alpha, respectively). Both IFN-alpha and IFN-gamma concurrently decreased steady-state expression of type I and type III procollagen messenger RNAs (mRNAs) in quiescent MFBIC. Viability assays ruled out cytotoxic effects of the two molecules. Finally, both IFNs decreased smooth muscle alpha-actin (SM alpha-actin) expression, whether assayed by immunoblotting or by Northern blot analysis. We conclude that IFN-alpha and IFN-gamma inhibit proliferation as well as collagen synthesis in human MFBIC.

EORTC (30885) randomised phase III study with recombinant interferon alpha and recombinant interferon alpha and gamma in patients with advanced renal cell carcinoma. The EORTC Genitourinary Group

In the treatment of renal cell carcinoma both complete (CRs) and partial remissions (PRs) have been obtained using recombinant (r) interferon alpha (IFN-alpha), with response rates ranging from 0 to 31% (mean 16%). rIFN-gamma is a potent immunostimulating agent, but the clinical experience of its use is limited and results are conflicting. In a phase II study with the combination of rIFN-alpha 2c (Boehringer Ingelheim) and rIFN-gamma (Genentech, supplied by Boehringer Ingelheim) in 31 eligible patients, a response rate of 25% was recorded. Based on this observation a randomised phase III study was initiated to investigate the possible advantage of the addition rIFN-gamma to rIFN-alpha 2c treatment. Treatment consisted of rIFN-alpha 2c 30 micrograms m-2 = 10 x 10(6) IU m-2 s.c. twice weekly in arm A and the same dose of rIFN-alpha combined with rIFN-gamma 100 micrograms m-2 = 2 x 10(6) IU m-2 in arm B. Eligibility criteria included documented progression of disease; patients with bone lesions only and overt central nervous system metastases were excluded. Between November 1988 and September 1990, 102 patients were entered into the study. An interim analysis showed a response in 7/53 (13%) patients (two CRs and five PRs) in the rIFN-alpha 2c monotherapy arm and in 2/45 (4%) (one CR and one PR) patients in the combination arm. This difference was not statistically significant (P = 0.17). The probability of missing an eventual 10% advantage for the combination is 0.001. The numbers are insufficient to rule out a negative effect of the addition of rIFN-gamma. The dose intensity of IFN-alpha 2c for the two treatment arms was the same. The addition of rIFN-gamma does not improve the response rate of rIFN-alpha 2c monotherapy. A possible detrimental effect cannot be excluded.

The role of tumor necrosis factor in viral disease

Tumor Necrosis Factor (TNF) is one of the many cytokines that comprise a complex intertwined network of biological response modifiers that takes on extreme significance as the host response to infectious diseases. Soluble factors such as Interleukin-2 and Interferon-gamma released by T cells and Interleukin-1, Interleukin-6 and TNF released by monocytes have been shown to play key roles in proliferation, activation and differentiation of immune cells. It has also become evident that development of treatment modalities for infectious diseases is complicated by the complexity of this cytokine network. In the last decade numerous reports have presented data, often conflicting, which clearly demonstrate a role for TNF in the response to infections caused by viruses. This review summarizes this rapidly growing volume of data, discussing consistencies and discrepancies as appropriate. By better understanding the role of TNF in the host immune response, it may be possible to modulate this complex network for the benefit of the host in its battle against viral infection.

Differential replication of human immunodeficiency virus type 1 in CD8- and CD8+ subsets of natural killer cells: relationship to cytokine production pattern

CD8+ and CD8- subsets of peripheral blood natural killer (NK) cells were examined for susceptibility to infection with human immunodeficiency virus type 1 (HIV-1) and for the ability to produce various types of interferon (IFN) and tumor necrosis factor (TNF). HIV-1 was preferentially grown in CD8+ NK cells. The ability of CD8- NK cells to suppress HIV-1 replication was related to their ability to produce alpha IFN (IFN-alpha) upon viral induction. Induction with interleukin-2 resulted in IFN-gamma production in both subsets of NK cells. In the CD8+ subset, IFN-gamma and HIV-1 mutually enhanced the production of TNF alpha, leading to hyperactivation of viral replication, whereas in CD8- NK cells IFN-gamma primed HIV-induced IFN-alpha production. The dichotomous effects of IFN-gamma on HIV-1 replication were dependent on the IFN-alpha-producing ability of the cellular targets. These findings can explain the selective depletion of the CD16+ CD8+ subset that begins early in the in vivo HIV-1 infection.

Partial phenotypic reversion of HeLa cells by long-term interferon-alpha treatment

Human papillomaviruses (HPV) are associated with malignant cervical neoplasia. Several HPV-related diseases have been shown to be sensitive to interferon (IFN) treatment. HeLa cells contain and express the HPV type 18 genome and were used as a model for the evaluation of the viral expression regulation and the effect on the malignant phenotype during IFN treatment. Cells were treated continuously with 200 IU/ml IFN-alpha 2b or natural leukocyte INF-alpha for six passages (42 days). Some IFN-induced changes were observed: decrease of HPV-18 mRNA expression, changes of cell morphology, and reduction of clonogenicity in soft agar. Tumorigenicity in nude mice was not modified. Other targets of the IFN system were analyzed, and an increase of the 2',5'-oligoadenylate synthetase mRNA level and a down-regulation of type I IFN receptor were found. These results demonstrate that long-term IFN-alpha treatment induces a partial phenotypic reversion of HeLa cells to a more differentiated stage were down-regulation of HPV-18 expression could play a central role. It therefore confirms that the IFN-alpha treatment may be therapeutically useful in cervix cancer produced by HPV-18.

Interleukin-2 and interferon in renal cell carcinoma

Renal cell cancer (RCC) represents an unusual solid tumor for which no treatment other than surgical therapy has been effective. This tumor demonstrates a remarkably heterogeneous behaviour and rare reports of spontaneous regressions suggest an unusual sensitivity to host immunologic control. In recent years the rapid development in molecular genetics, growth factors and cytokine--lymphocyte interactions have increased the interest and possibilities for immunotherapy of RCC. Interleukin-2 (IL-2) or Interferon alpha (IFN alpha) alone are only marginally active in RCC. Their different modes of action and their synergistic effects when used in experimental murine models prompted the investigation of combined IL-2/INF alpha therapy in advanced RCC. The advantage of a combination of IL-2 and IFN alpha treatment as compared to LAK cell treatment seems to be that IL-2 and IFN alpha can be given at lower dosages without compromising the results in an outpatient setting. This article reviews the use of IL-2 and IFN alpha in combination for treatment of RCC and discusses the current problems and future challenges in this field.

Alpha- and gamma-interferon versus alpha-interferon alone in chronic hepatitis B. A randomized controlled study

Thirty-two patients with chronic hepatitis B were randomly assigned to two groups. Sixteen patients received 10 million units of alpha-interferon per square meter of body surface (MU/m2), three times weekly for 4 months. Sixteen patients were treated simultaneously with gamma-interferon at a dose of 2 MU/m2, and 10 MU/m2 of alpha-interferon. At the end of the study (13th month), hepatitis B virus DNA was negative in 50% of the patients treated with alpha-interferon and in only 25% of those treated with alpha- and gamma-interferon. A similar trend was observed with respect to the hepatitis B e antigen negativization (31% and 19% of HBeAg negativization in patients treated with alpha- and gamma-interferon, respectively). In summary, these data demonstrate that, at the doses used in this study, the combination of alpha- and gamma-interferon does not give better results than the administration of alpha-interferon alone. The tolerance to simultaneous alpha- and gamma-interferons is poor and may decompensate the liver disease.