Automated, quantitative cytopathic effect reduction assay for interferon

Lymphocyte Subsets in the Nasal Mucosa and Peripheral Blood during Experimental Rhinovirus Infection

The local cellular response during rhinovirus infection was studied with immunohistochemical staining of lymphocyte subpopulations in the lamina propria of the nasal mucosa (inferior turbinate) in 25 biopsies from volunteers with experimental rhinovirus colds and compared with biopsies from healthy volunteers. Biopsies from rhinovirus infected volunteers, taken either in the early phase of the infection (days 3 and 5) or during convalescence (day 14) were evaluated in a semiquantitative fashion for degree of infiltration. Lymphocyte subpopulations also were counted on coded specimens.

During experimental rhinovirus infection, no change could be observed in the overall degree of lymphocytic infiltration or in the numbers of T and B lymphocytes compared with control specimens. The overall degree of lymphocyte infiltration in the nasal mucosa was mild to moderate and consisted principally of T lymphocytes and only a few scattered B lymphocytes. Few natural killer lymphocytes were seen. These findings are similar to those in normal nasal mucosa and in contrast to the findings after topical application of recombinant interferon, which often results in a heavy lymphocyte infiltration. Lymphocyte subpopulation in the peripheral blood did not change when compared with prechallenge values in nine rhinovirus-infected volunteers.

The antimalarial drug amodiaquine possesses anti-ZIKA virus activities

Zika virus (ZIKV) outbreak has emerged as a global health threat, particularly in tropical areas, over the past few years. No antiviral therapy or vaccine is available at present. For these reasons, repurposing clinically approved drugs against ZIKV infection may provide rapid and cost-effective global health benefits. Here, we explored this strategy and screened eight FDA-approved drugs for antiviral activity against ZIKV using a cell-based assay. Our results show that the antimalarial drug amodiaquine has anti-ZIKV activity with EC₅₀ at low micromolar concentrations in cell culture. We further characterized amodiaquine antiviral activity against ZIKV and found that it targets early events of the viral replication cycle. Altogether, our results suggest that amodiaquine may be efficacious for the treatment of ZIKV infection.

Naturally Occurring Fc-Dependent Antibody From HIV-Seronegative Individuals Promotes HIV-Induced IFN-α Production

A majority of adults without HIV infection and with a low risk of HIV-exposure have plasma IgG antibodies that enhance the rate and magnitude of HIV-induced interferon alpha (IFN-α) production. Fc-dependent IgG-HIV complexes induce IFN-α rapidly and in high titers in response to HIV concentrations that are too low to otherwise stimulate an effective IFN-α response. IFN-α promoting antibody (IPA) counters HIV-specific inhibition of IFN-α production, and compensates for the inherent delay in IFN-α production common to HIV infection and other viruses. Naturally occurring IPA has the potential to initiate a potent IFN-α response early in the course of HIV mucosal invasion in time to terminate infection prior to the creation of a pool of persistently infected cells. The current study adds IPA as a mediator of an Fc-dependent antiviral state capable of preventing HIV infection.

Establishment of a stable CHO cell line with high level expression of recombinant porcine IFN-β

A CHO cell clone (CHO-PoIFN-β) with stable porcine IFN-β expression under control of CMV promoter was selected under G418 pressure. In a 25 cm² cell culture flask (5 ml culture medium), the cumulative protein yield of recombinant PoIFN-β reached 2.3 × 10⁶ IU/ml. This cells clone maintained stable expression for at least 20 generations even in the absence of G418 selection pressure. The expressed recombinant PoIFN-β could induce the expression of porcine Mx protein in PK15 cells, and activate the chicken Mx promoter-controlled luciferase reporter gene expression, confirming that the recombinant PoIFN-β has the biological activity of natural porcine type-I interferon. In addition, the recombinant PoIFN-β fully protected PK15 cells against 1000 TCID₅₀ of porcine transmissible gastroenteritis virus and pseudo-rabies virus infection, demonstrating its high potential in therapeutic applications. This is the first report of establishing a mammalian cell line with stable expression of porcine IFN-β.

Identification of alpha interferon-induced genes associated with antiviral activity in Daudi cells and characterization of IFIT3 as a novel antiviral gene

A novel assay was developed for Daudi cells in which the antiviral (AV) and antiproliferative (AP) activities of interferon (IFN) can be measured simultaneously. Using this novel assay, conditions allowing IFN AV protection but no growth inhibition were identified and selected. Daudi cells were treated under these conditions, and gene expression microarray analyses were performed. The results of the analysis identified 25 genes associated with IFN-α AV activity. Upregulation of 23 IFN-induced genes was confirmed by using reverse transcription-PCR. Of 25 gene products, 17 were detected by Western blotting at 24 h. Of the 25 genes, 10 have not been previously linked to AV activity of IFN-α. The most upregulated gene was IFIT3 (for IFN-induced protein with tetratricopeptide repeats 3). The results from antibody neutralizing experiments suggested an association of the identified genes with IFN-α AV activity. This association was strengthened by results from IFIT3-small interfering RNA transfection experiments showing decreased expression of IFIT3 and a reduction in the AV activity induced by IFN-α. Overexpression of IFIT3 resulted in a decrease of virus titer. Transcription of AV genes after the treatment of cells with higher concentrations of IFN having an AP effect on Daudi cells suggested pleiotropic functions of identified gene products.

B and CD4+ T-cell expression of TLR2 is critical for optimal induction of a T-cell-dependent humoral immune response to intact Streptococcus pneumoniae

TLR2(-/-) mice immunized with Streptococcus pneumoniae (Pn) elicit normal IgM, but defective CD4(+) T-cell-dependent type 1 IgG isotype production, associated with a largely intact innate immune response. We studied the T-cell-dependent phosphorylcholine (PC)-specific IgG3 versus the T-cell-independent IgM response to Pn to determine whether TLR2 signals directly via the adaptive immune system. Pn-activated TLR2(-/-) BMDC have only a modest defect in cytokine secretion, undergo normal maturation, and when transferred into naïve WT mice elicit a normal IgM and IgG3 anti-PC response, relative to WT BMDC. Pn synergizes with BCR and TCR signaling for DNA synthesis in purified WT B and CD4(+)T cells, respectively, but is defective in cells lacking TLR2. Pn primes TLR2(-/-) mice for a normal CD4(+) T-cell IFN-gamma recall response. Notably, TLR2(-/-) B cells transferred into RAG-2(-/-) mice with WT CD4(+)T cells, or TLR2(-/-) CD4(+)T cells transferred into athymic nude mice, each elicit a defective IgG3, in contrast to normal IgM, anti-PC response relative to WT cells. These data are the first to demonstrate a major role for B-cell and CD4(+) T-cell expression of TLR2 for eliciting an anti-bacterial humoral immune response.

Antibody-mediated enhancement of the rate, magnitude, and responsiveness of vesicular stomatitis virus induced alpha interferon production

A majority of adults without evidence of exposure to vesicular stomatitis virus (VSV) have serum IgG antibodies that interact with pro-inflammatory TLR7 in the presence of VSV, and enhance several aspects of VSV-induced IFN-alpha production. Enhancing IgG antibody enables human PBMC to make IFN-alpha more rapidly and in higher titers in response to a broad range of VSV-concentrations that include those too low to independently stimulate IFN-alpha production. These antibody-mediated functions compensate for the inherent delay in virus-induced IFN-alpha production in vitro, and have the potential to improve the in vivo IFN-alpha response and effectively terminate infection before the occurrence of clinically apparent disease. The frequent presence of enhancing antibody in persons without predictable VSV exposure has implications for naturally occurring infections with this and other viruses, and for the use of viruses as vaccine vectors and oncolytic agents.

Measurement of antiviral activity induced by interferons alpha, beta, and gamma

The Basic Protocol in this unit describes an assay for murine IFN-induced antiviral activity and employs vesicular stomatitis virus (VSV) and IFN-sensitive fibroblasts. Support Protocol describes the preparation of VSV cultures and the calculation of multiplicity of infection (MOI; i.e., concentration of viral particles required to infect cells). Support Protocol describes the antibody neutralization assay, which can be used to identify the bioactive species of IFN in a sample, or to test the potency of an antibody preparation against a particular species of IFN. Alternate Protocol 1 covers measurement of human IFN-induced antiviral activity; while the steps are quite similar to Basic Protocol, different viral and cell cultures are described.

Two interferons alpha influence each other during their interaction with the extracellular domain of human type interferon receptor subunit 2

The interaction between two human interferons alpha (IFN-alphas) and the extracellular (EC) domain of human type I IFN receptor subunit 2 (IFNAR2) was analyzed. Previous experiments using Daudi cells showed that IFN-alpha21b and some IFN-alpha hybrids (made from IFN-alpha2c and 21b) competed poorly for the IFN-alpha2b binding site. This study examined the causes of the poor competition between these IFN-alphas. IFN-alpha2c and the IFN hybrid CM3 {IFN-alpha21b(1-75)(81-95)/IFN-alpha2c(76-80) (96-166), Y86K} were selected for this study based on their cell binding and biological properties. Competitive binding ELISA, native electrophoresis followed by Western blot, electrospray ionization mass spectrometry (ESI-MS), surface plasmon resonance biosensor (SPR) analysis, as well as neutralization of antiproliferative activities on Daudi cells in the presence of soluble IFNAR2-EC show evidence that each of the described IFN-alpha subtypes affected the binding of the other IFN-alpha to IFNAR2-EC by affecting the stability of the complex, i.e., dissociation of the complex. Moreover, native electrophoresis with different IFNAR2-EC mutants showed that IFN-alpha2c and CM3 utilize different amino acids in the binding domain of IFNAR2-EC. In addition to that, analytical ultracentrifugation (AUC) revealed differences in the oligomeric state of the two studied interferons. Our results demonstrated that two individual IFN-alphas interact differentially with IFNAR2-EC and influence each other during this interaction. This study contributes to the understanding of the mutual interaction between multiple IFN-alpha subtypes during the competition for binding to the receptor.

Binding Characteristics of IFN-alpha Subvariants to IFNAR2-EC and Influence of the 6-Histidine Tag

The expression, purification, detection, and assay of recombinant proteins have been made more convenient and rapid by the use of small affinity tags. To facilitate the purification of interferon-alpha2c (IFN-alpha2c) by metal chelate affinity chromatography, N-terminal 6-histidine tag was introduced via genetic manipulation. Two preparations of IFN material were purified; one contained IFN-alpha2c with the 6-histidine tag, and the other contained IFN-alpha2c without the 6-histidine tag. The antigenic properties of the human IFN-alpha2c subvariant with and without the 6-histidine tag, as well as the effects of the N-terminal 6-histidine tag on IFN-alpha2c interaction with the extracellular domain of human IFN-alpha receptor chain 2 (IFNAR2-EC) were examined. For the purposes of this study, IFNs were characterized by Western blots with anti-IFN monoclonal antibodies (mAb) and bioassays. Immunoblot analyses showed differences between IFN-alpha2c-6-histidine tag and IFN-alpha2a, b, c in their interaction with IFNAR2-EC. We also observed differences between IFN-alpha2c-6-histidine tag and IFN-alpha2a, b, c in bioactivities. This study is the first report that shows that an N-terminal 6-histidine tag on IFN-alpha2c can affect its interaction with receptor and cause a different bioactivity.

The Interferon Regulatory Factor, IRF5, Is a Central Mediator of Toll-like Receptor 7 Signaling

Interferon regulatory factors (IRFs) are critical components of virus-induced immune activation and type I interferon regulation. IRF3 and IRF7 are activated in response to a variety of viruses or after engagement of Toll-like receptor (TLR) 3 and TLR4 by double-stranded RNA and lipopolysaccharide, respectively. The activation of IRF5, is much more restricted. Here we show that in contrast to IRF3 and IRF7, IRF5 is not a target of the TLR3 signaling pathway but is activated by TLR7 or TLR8 signaling. We also demonstrate that MyD88, interleukin 1 receptor-associated kinase 1, and tumor necrosis factor receptor-associated factor 6 are required for the activation of IRF5 and IRF7 in the TLR7 signaling pathway. Moreover, ectopic expression of IRF5 enabled type I interferon production in response to TLR7 signaling, whereas knockdown of IRF5 by small interfering RNA reduced type I interferon induction in response to the TLR7 ligand, R-848. IRF5 and IRF7, therefore, emerge from these studies as critical mediators of TLR7 signaling.

The C protein of measles virus inhibits the type I interferon response

Type I interferons (IFNalpha/beta) are an important part of innate immunity to viral infections because they induce an antiviral response and limit viral replication until the adaptive response clears the infection. Since the nonstructural proteins of several paramyxoviruses inhibit the IFNalpha/beta response, we chose to explore the role of the C protein of measles virus (MV) in such inhibition. Previous studies have suggested that the MV C protein may serve as a virulence factor, but its role in the pathogenesis of MV remains undefined. In the present study, a recombinant MV strain that does not express the C protein (MV C-) and its parental strain (Ed Tag) were used. Growth of MV C- was restricted in human peripheral blood mononuclear cells and HeLa cells, but in the presence of neutralizing antibodies to IFNalpha/beta, MV C- produced titers that were equivalent to those of Ed Tag. In addition, expression of the MV C protein from plasmid DNA inhibited the production of an IFNalpha/beta responsive reporter gene and, to a lesser extent, inhibited an IFNgamma responsive reporter gene. The ability of the MV C protein to suppress the IFNalpha/beta response was confirmed using a biologic assay. After IFNbeta stimulation, HeLa cells infected with Ed Tag produced five-fold less IFNalpha/beta than cells infected with MV C-. While the mechanism of inhibition remains unclear, these data suggest that the MV C protein plays an important role in the pathogenesis of MV by inhibiting IFNalpha/beta signaling.

Immune-specific immunoglobulin G-mediated enhancement of human immunodeficiency virus-induced IFN-alpha production

Interferon-alpha (IFN-alpha) is synthesized as an integral part of innate immunity to viral infection. We previously provided preliminary evidence that antibody-containing serum from HIV-infected individuals enhanced HIV-induced production of IFN-alpha. Subsequently, preparations of pooled human immunoglobulin G (IgG) have also been shown to enhance poliovirus (PV)-induced IFN-alpha production. The current work establishes IgG as the serum mediator that enhances induction of IFN-alpha by HIV. Our studies also establish the ability of sera from individual subjects to enhance PV-induced IFN-alpha production. HIV-induced IFN-alpha production was enhanced maximally by >4000-fold and by an average of 25-fold. Sera from 74 people enhanced PV- induced IFN-alpha from undetectable levels to an average of 615 units (range 7-4679 units). The ability of individual sera to enhance IFN-alpha production by HIV and PV persisted undiminished in patients with AIDS. IgG-mediated enhancement of IFN-alpha production was similar to that induced by IgG and PV and was blocked by IgG Fc fragments. Demonstration of the selective enhancement of HIV-induced IFN-alpha production by IgG from HIV-seropositive individuals provides further evidence for the existence of antigen-specific upregulation of a critical component of innate antiviral immunity by the adaptive Th2 immune response.

Efficient enhancement of priming effect by intermittent treatment with interferon

To improve the efficacy of interferon (IFN) therapy for chronic hepatitis C, we proposed a therapy with twice-a-day injection of IFNbeta as the induction. To assess its biological enhancement, we compared antiviral activities in vitro using intermittent treatment schedules simulating the clinical condition. FL cells were treated with IFNbeta twice in 12 h interval (Single treatment, 1000 and 0 IU/ml; Double treatment, 500 IU/ml each) and challenged with Sindbis virus. Antiviral activities were determined with 50% cytopathic effect. Activities and mRNA expressions of 2'5'oligoadenylate synthetase (2'5'AS) were also examined. Single treatment showed its peak activity at 9 h, while Double treatment was at 3 h after the second treatment. Double treatment had a significantly higher peak activity. The up-regulated activities of 2'5'AS lasted much longer with Double treatment. The present findings demonstrated Double treatment could induce efficient biological enhancement, which is thought based on the priming effect.

Evasion of host defenses by measles virus: wild-type measles virus infection interferes with induction of Alpha/Beta interferon production

Measles is a highly contagious disease currently responsible for over one million childhood deaths, particularly in the developing world. Since alpha/beta interferons (IFNs) are pivotal players both in nonspecific antiviral immunity and in specific cellular responses, their induction or suppression by measles virus (MV) could influence the outcome of a viral infection. In this study we compare the IFN induction and sensitivity of laboratory-passaged attenuated MV strains Edmonston and Moraten with those of recent wild-type viruses isolated and passaged solely on human peripheral blood mononuclear cells (PBMC) or on the B958 marmoset B-cell line. We report that two PBMC-grown wild-type measles isolates and two B958-grown strains of MV induce 10- to 80-fold-lower production of IFN by phytohemagglutinin-stimulated peripheral blood lymphocytes (PBL) compared to Edmonston and Moraten strains of measles. Preinfection of PBL with these non-IFN-inducing MV isolates prevents Edmonston-induced but not double-stranded-RNA-induced IFN production. This suggests that the wild-type viruses can actively inhibit Edmonston-induced IFN synthesis and that this is not occurring by double-stranded RNA. Furthermore, the wild-type MV is more sensitive than Edmonston MV to the effect of IFN. MV is thus able to suppress the synthesis of the earliest mediator of antiviral immunity, IFN-alpha/beta. This could have important implications in the virulence and spread of MV.

Successful treatment of herpetic infections by autohemotherapy

Herpes zoster (shingles) affects a significant number of individuals over age 50. To date, no satisfactory treatment has been available. The clinician author (JHO) witnessed a dramatic response of a shingles patient to autohemotherapy: the pain was completely relieved and lesions gone within 5 days with no recurrence of either. Treatment of other herpetic patients then began with autohemotherapy. Twenty-five patients with herpes were given an autologous blood transfer of 10 mL of blood from the antecubital vein into the gluteal bundle and followed for clinical signs. A 100% favorable response occurred in 20 patients who received autohemotherapy within 7 weeks of the onset of clinical signs and 1 other who received autohemotherapy at a 9-week interval. No untoward signs or symptoms of the treatment occurred. Autohemotherapy has been demonstrated to be effective in elimination of clinical sequelae in these cases of herpes infections and these results justify further rigorous clinical investigation.

Cystamine potently suppresses in vitro HIV replication in acutely and chronically infected human cells

We have investigated the effects of cystamine on the replication of human immunodeficiency virus (HIV) in human lymphocytes and macrophages, the natural targets of HIV in vivo. Treatment of chronically infected macrophages with cystamine, at a concentration (500 microM) that did not show any cytotoxic or cytostatic effects, strongly decreased (> 80%) HIV-p24 antigen production and completely abolished the production of infectious viral particles. Cystamine does not affect viral transcription, translation or protein processing; indeed, all HIV proteins are present in a pattern similar to that of nontreated cells. Instead, cystamine interferes with the orderly assembly of HIV virions, as shown by electron microscopy analysis, that reveals only defective viral particles in treated cells. Moreover, suppression of HIV replication, due to the inhibition of proviral DNA formation was observed in acutely infected lymphocytes and macrophages pretreated with cystamine. These results show that cystamine potently suppresses HIV replication in human cells by contemporaneously blocking at least two independent steps of the viral life cycle, without affecting cell viability, suggesting that this compound may represent a new possibility towards the treatment of HIV-1 infection.

Polyethylene Glycol Enhanced Protein Refolding

Previous studies on the refolding of recombinant bovine carbonic anhydrase B (CAB) indicated that polyethylene glycol (PEG) significantly enhanced the recovery of active protein by reducing aggregation. To further test the ability of PEG to enhance refolding, three recombinant human proteins, deoxyribonuclease (rhDNAse), tissue plasminogen activator (rhtPA), and interferon-gamma (rhIFN-gamma) were refolded in the presence of PEG (3350 MW). rhDNAse produced from CHO cells was denatured in 7.2 M urea and refolded by rapid dilution to 4.0 M urea and 0.20 mg/ml protein. When a final PEG to rhDNAse molar ratio of 5 to 1 (0.1 milligram PEG, 3350 MW) was used in the dilution buffer, refolding was improved by 30% to yield complete recovery of active protein. Impure E. coli derived inclusion body preparations of rhDNAse were solubilized in 8 M urea and refolded by dilution to 4 M urea and 0.10 mg/ml protein. Refolding with a dilution buffer which yielded a final PEG to rhDNAse molar ratio of 10 to 1 (0.1 milligram PEG, 3350 MW) resulted in a three-fold increase in the recovery of active protein. When PEG was used in the dilution buffer, aggregation of rhDNAse did not occur during refolding in either case. rhtPA produced from CHO cells was denatured in 5 M guanidine hydrochloride (GuHCl) and refolded by rapid dilution to 0.10 M GuHCl and 0.20 mg/ml protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Control of H-2 expression in transformed nonhaemopoietic cells by autocrine interferon

The relationship between autocrine interferon (IFN) production and the expression of class I Major Histocompatibility Complex (MHC) membrane glycoproteins in vitro was investigated in a panel of murine transformed cells of nonhaemopoietic origin. The panel included 11 cell lines of H-2Kb haplotype derived from fibrosarcomas, carcinomas and melanoma, and from transformed fibroblasts. IFN activity was detected in the conditioned medium of nine cell lines; fibrosarcomas were among the high IFN producers, while the non-producers were a melanoma clone and a lung carcinoma cell line. A significant correlation was found between IFN production and the expression of H-2K/D glycoproteins, thus suggesting that long-term maintainment of MHC glycoprotein expression in vitro could be mediated by self produced IFN. Two IFN producer cell lines, MN/MCA1 and R80/17, were cultured in the presence of a blocking antiserum against IFN-alpha/beta: a significant decrease in H-2b expression was observed, thus indicating the existence of an autocrine IFN circuit. Taken together these findings suggest that release of IFN is a frequent event among transformed nonhaemopoietic cells, and that self-produced IFN contributes to the regulation of MHC antigen levels in solid tumours.

Human U937 cell surface peptidase activities: characterization and degradative effect on tumor necrosis factor-α

Surface peptidase activities on the human monocytic lineage cell line U937 were characterized. Two diisopropyl phosphofluoridate (DFP)-inhibitable serine peptidases were identified by differences in their hydrolytic activities on chromogenic peptides: one removed tripeptides from the free NH2-terminal end of the synthetic peptide Ala-Ala-Phe-p-nitroanilide (pNA) and was not inhibited by inhibitors of metallo-, cysteic-, and aspartic-proteinases, or by those of elastase-, trypsin- and chymotrypsin-like enzymes, suggesting the presence of a hitherto unidentified serine tripeptidyl endopeptidase; the other peptidase catalyzed the release of Gly-Pro from Gly-Pro-pNA and was inhibited by DFP, phenylmethyl sulfonyl fluoride and diprotin A, thus resembling dipeptidyl peptidase IV (DPP IV) with respect to its substrate specificity and inhibitor profile. A group of N-exo-aminopeptidase activities specifically inhibited by bestatin, was also detected when Ala-, Leu-, Arg- and Lys-pNA were used a substrates. The activities were surface associated and not secreted as determined by extracellular location of product and enzymatic recovery in highly purified U937 cell membranes. Peripheral monocytes and macrophages were found to virtually exhibit identical levels of these two classes of peptidase activities when compared to those detected on U937 cells. The relative contributions of these hydrolytic enzymes to the cleavage of bioactive and radioiodinated cytokines including tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha and interferon-gamma was next examined. The results indicated that N-aminopeptidases do not appear to participate in the catabolism of any tested cytokine. In contrast, the most interesting finding was that both serine peptidases participate in TNF-alpha degradation. Analysis of the final proteolytic digestion products demonstrated the disappearance of the native 17-kDa molecule TNF-alpha, and the concomitant release of biologically inactive fragments of less than or equal to 2 kDa. Together, these observations indicate new roles for both the DPP IV-like enzyme and the tripeptidyl endopeptidase located at the surface of human monocytic cells, including the regulation of the extracellular TNF-alpha concentration. Thus, the identification of functional ectopeptidases provides insight into their potential role in both normal and malignant monocytic function.

Gamma interferon suppresses acute and chronic Trypanosoma cruzi infection in cyclosporin-treated mice

To determine if exogenous gamma interferon is effective in immunosuppressed mice infected with Trypanosoma cruzi, recombinant murine gamma interferon was administered to cyclosporin-treated mice with either acute or chronic T. cruzi infection. Gamma interferon significantly decreased parasitemia and prevented death in acutely infected mice. Parasitemias and mortality of mice treated with both gamma interferon and cyclosporin were similar to those of immunocompetent controls. In chronically infected mice, cyclosporin treatment produced significantly more organ explant cultures positive for T. cruzi. Fewer positive cultures, particularly for spleen and heart, were obtained from cyclosporin-treated mice when they also received gamma interferon. Ketoconazole treatment of mice resulted in no positive cultures. Cyclosporin treatment did not prevent activation of peritoneal macrophages by parenteral gamma interferon, nor did it have a consistent effect on serum titers of alpha/beta or gamma interferon in response to a second challenge inoculum of T. cruzi. These data indicate that exogenous gamma interferon suppresses acute and chronic T. cruzi infection in cyclosporin-treated mice but that gamma interferon is not as effective as the relatively specific antimicrobial ketoconazole. Gamma interferon activates macrophages despite cyclosporin treatment, and its effects appear to be tissue specific.

A selective defect of interferon alpha production in human immunodeficiency virus-infected monocytes

Interferon alpha (IFN-alpha) induces significant antiretroviral activities that affect the ability of human immunodeficiency virus (HIV) to infect and replicate in its principal target cells, CD4+ T cells and macrophages. A major endogenous source of IFN-alpha during any infection is the macrophage. Thus, macrophages have the potential to produce both IFN-alpha and HIV. In this study, we examined the production of IFN-alpha and other cytokines by macrophage colony-stimulating factor (M-CSF)-treated cultured monocytes during HIV infection. Tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), IL-6, IFN-omega, or IFN-beta were not detected nor was the mRNA expressed in either uninfected or HIV-infected monocytes. However, both uninfected and HIV-infected monocytes produced high levels of each of these cytokines after treatment with synthetic double-stranded RNA [poly(I).poly(C)]. Uninfected monocytes also produced high levels of IFN-alpha after treatment with poly(I).poly(C), Newcastle disease virus, or herpes simplex virus. In marked contrast to the preceding observations, HIV-infected monocytes produced little or no IFN-alpha before or after treatment with any of these agents. The absence of detectable IFN-alpha activity and mRNA in poly(I).poly(C)-treated HIV-infected monocytes was coincident with high levels of 2',5' oligoadenylate synthetase and complete ablation of HIV gene expression. The antiviral activity induced by poly(I).poly(C) may be a direct effect of this synthetic double-stranded RNA or secondary to the low levels of IFN-beta and IFN-omega produced by infected cells. The markedly diminished capacity of HIV-infected monocytes to produce IFN-alpha may reflect a specific adaptive mechanism of virus to alter basic microbicidal functions of this cell. The inevitable result of this HIV-induced cytokine dysregulation is virus replication and persistence in mononuclear phagocytes.

A three-dimensional model to analyze drug-drug interactions

Nearly four generations of investigators have studied combined drug effects. Their methods of generating and analyzing data have changed dramatically over the years but the basic problem has not. This review examines the inherent difficulties in analyzing combined drug effects and evaluates modern methods of describing these interactions. Researchers have traditionally used two-dimensional (2-D) methods to approximate the actual three-dimensional (3-D) nature of drug interactions. We conclude that these 2-D methods are often inadequate when used to analyze synergistic and antagonistic drug interactions in antiviral and anticancer chemotherapy. We propose a direct and pragmatic 3-D approach to the problem, made possible by microcomputers and sophisticated graphics programs. This procedure directly elucidates the shape of the dose-response surface, identifies the regions of statistically significant synergy and antagonism, and quantitates these effects. It also greatly simplifies the problem since a 3-D surface presents complete drug interactions in a way that can be easily interpreted. We will show that understanding the shape of the resulting 3-D surface is essential to an understanding of complex drug interactions. This new method facilitates the rigorous analysis of drug-drug interactions and offers investigators powerful new tools to analyze combinations of antiviral and anticancer drugs.

Effects of cytokines on human thymic epithelial cells in culture: IL1 induces thymic epithelial cell proliferation and change in morphology

The role of thymic epithelium in T cell development has given rise to a number of studies, but less information is available concerning the factors regulating thymic epithelial cells (TEC) themselves. Several cytokines, natural or recombinant, were investigated for their effects on human TEC proliferation. This study presents evidence for the first time that human recombinant interleukin 1 (IL1) and IL1-containing mixed cytokine preparations induced DNA synthesis of TEC as measured in a 48-hr stimulation assay. The effects of IL1 were dose dependent and sustained in time. The following recombinant cytokines, IL2, IL3, IL4, interferon-gamma (IFN-gamma), IFN-alpha, tumor necrosis factor-alpha (TNF alpha), and TNF beta, as well as thymosin fraction 5 and Escherichia coli lipopolysaccharide (LPS), were not found to modify TEC proliferation but IFN-gamma and TNF alpha enhanced the effects of IL1. We also report that IL1 induced a profound change in the morphology of TEC. Our observations suggest that TEC are targets for the action of cytokines and emphasize the important role played by IL1 within the thymus.

Treatment of malignant metastatic midgut carcinoid tumours with recombinant human alpha2b interferon with or without prior hepatic artery embolization

Nineteen patients with histologically verified midgut carcinoid tumours and liver metastases were included in a prospective study with daily recombinant human alpha 2b interferon injections of 5 million IU subcutaneously for 1 year. All had as much as possible of the primary tumour removed at laparotomy. Whenever technically possible (in seven cases), an embolization of the hepatic arteries was performed before interferon start. The response rate of the combined embolization and interferon treatment (n = 7) was 86% after 1 year, as judged from either a 50% reduction in excretion of 5-hydroxy-3-indoleacetic acid in the urine or a 50% reduction in the area of the largest liver metastasis as evaluated by computed tomography. All patients experienced an improvement in diarrhoea and/or flushing. When interferon was given alone (n = 12), 40% responded on the basis of objective criteria (50% after 6 months), whereas an improvement in either diarrhoea or flushing was experienced by 70% (75% after 6 months). In this group one patient had died and one had decided to withdraw after 6 months, at which time both were responders. We conclude that interferon seems to be an effective treatment of malignant metastatic midgut carcinoid tumours and that embolization of the liver arteries seems to increase the response rate, as judged after 1 year.

Dipyridamole potentiates the inhibition by 3'-azido-3'-deoxythymidine and other dideoxynucleosides of human immunodeficiency virus replication in monocyte-macrophages

Dipyridamole (DPM) is commonly used as a coronary vasodilator and inhibitor of platelet aggregation in the treatment of cardiovascular diseases. We report here that DPM potentiates the inhibitory effects of 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxycytidine against human immunodeficiency virus type 1 (HIV-1) in human monocyte-macrophages. At the same concentrations, DPM does not potentiate the toxic effects of AZT on these cells or on human bone marrow (granulocyte-monocyte) progenitor cells. Since monocyte-macrophage lineage cells appear to be the major reservoir for HIV-1 in vivo, these findings suggest the possibility of using DPM or its analogues in combination chemotherapy of HIV infections.

Measles virus-induced suppression of lymphocyte proliferation

The mechanism by which measles virus induces immunosuppression was investigated using an in vitro system employing phytohemagglutinin (PHA)-induced human peripheral mononuclear cell (PBMC) proliferation. At a multiplicity of infection of 1.0 or greater measles virus significantly inhibited (45%) the proliferation of PBMC. This inhibition was not due to an alteration in the kinetics of proliferation. PHA-stimulated PBMC were then infected with measles virus for 72 hr and irradiated (3200 rad) to prevent further proliferation. These infected, irradiated PBMC when added to fresh autologous PBMC caused significant inhibition of lymphoproliferation over a wide range of infected:fresh cell ratios (maximum inhibition seen at a 1:1 ratio, 85% inhibition). Virus recovered from the irradiated, infected cells was 100-fold lower than the virus titer needed to cause inhibition by direct addition of measles virus. However, antibody to measles virus reversed the inhibition. Virus-free supernatant fluids from the infected irradiated cells caused immunosuppression of the PHA response. This immunosuppressive material induced by the measles virus was maximally produced after 72 hr and did not appear to require viral replication. This factor was not prostaglandin E or interferon-alpha or -gamma. The production of such suppressive factors during viral infection may explain some of the profound immunosuppression seen in situations in which little or no infectious virus can be detected.

Phase I/II study of recombinant interferon gamma in advanced renal cell carcinoma

A phase I and II evaluation of 42 patients with advanced renal cell carcinoma treated with recombinant interferon gamma was done. Patients were treated with either a daily 2-hour infusion or 24-hour infusion for 7 days every 3 weeks for at least 2 cycles. Patients who demonstrated stable disease or improvement on therapy then were continued on a maintenance program of 5 days of recombinant interferon gamma administered every 3 to 4 weeks. The initial starting dose was 10 mcg. per m.2 per day with escalations to 30, 100, 300, 1,000 and 3,000 mcg. per m.2. Dose-limiting toxicity occurred at 1,000 to 3,000 mcg. per m.2, and included leukopenia, chills, fevers, rigors and hepatotoxicity as manifested by elevation in the transaminase and bilirubin levels. Tumor responses were seen initially at the 300 mcg. per m.2 dose level. Over-all, of 41 patients evaluable for therapeutic effectiveness 1 demonstrated a complete response 6 months in duration and 3 demonstrated partial responses 2, 9 and 13 months in duration. However, 6 patients demonstrated organ site responsiveness, including resolution of pulmonary lesions (2 complete and 1 partial responses), lymphadenopathy (1 complete and 1 partial responses), a pleural-based lesion in 1 patient with a partial response and complete resolution of hepatic metastases in 1 patient. We conclude that recombinant interferon gamma at a dose of 1,000 to 3,000 mcg. per m.2 for 7 days and repeated every 2 to 3 weeks had demonstrable anticancer activity in patients with metastatic renal carcinoma.

Intranasal recombinant alfa-2b interferon treatment of naturally occurring common colds

In a double-blind, placebo-controlled study, patients with naturally occurring common colds of less than or equal to 48 h duration were randomly assigned to receive nasal sprays of recombinant alfa-2b interferon at 10 or 20 MU/day or placebo four times per day for 5 days. The 10-MU (n = 74), 20-MU (n = 74), and placebo (n = 72) groups had comparable frequencies of documented rhinovirus colds (50 to 65%) and mean durations of pretreatment symptoms (26 to 27 h). The median duration of colds tended to be longer in the 20-MU group (10 days) than the 10-MU group (8 days) or placebo group (8 days) (P = 0.06). In those with proven rhinovirus colds treated within 24 h, the median duration was significantly longer in the 20-MU group (9 days) than in the placebo group (6 days). No differences favoring interferon treatment were found in respiratory symptom scores or resolution of specific symptoms. On days 5 and 7, nasal washings from compliant subjects with proven rhinovirus colds yielded rhinoviruses more often in placebo (47 and 48%, respectively) than in interferon (15 and 16%, respectively) recipients (P less than 0.02), but no differences in new respiratory illness occurrence were observed in household contacts. Interferon recipients had significantly higher frequencies of blood in nasal mucus (16 to 18%) than did placebo recipients (4%) during treatment. Antibiotics for presumed secondary infections were given more often in the 20-MU group (11%) than in the placebo group (0%) (P less than 0.01). Nasal sprays of recombinant alfa-2b interferon were not an effective treatment for natural colds and were associated with toxicity.

Clinical overview of alpha interferon. Studies and future directions

The clinical development of the alpha interferons has now progressed through initial Phase I and II trials into extensive controlled clinical trial designs. Alpha interferon has been a prototype of other biological agents that are now in clinical development. These agents operate through fundamentally different mechanisms of action than conventional chemotherapy and have produced a unique profile of side effects as well as response patterns. Time to response is generally longer than with chemotherapy, and dose-response and schedule-dependency questions continue to be explored for most tumor types. Although response rates have been low against most solid tumors when alpha interferon is used as a single agent, it has demonstrated a surprisingly wide range of efficacy in hematologic malignancies. These include tumors of presumed B-cell, T-cell, and myeloid lineages. In some diseases, e.g., hairy cell leukemia and chronic myelogenous leukemia, alpha interferon is broadly effective; it appears to considerably reduce or occasionally eliminate the malignant clone while normalizing the peripheral blood counts in most patients. In other diseases, alpha interferon appears destined to play a major role as part of combination therapy or in maintenance or consolidation therapy. In other disease settings, alpha interferon's role continues to be explored as part of combination therapy, adjuvant therapy, or as local-regional therapy. The full potential of alpha interferon as an antineoplastic agent will not be determined for many years. In this paper, the results from the first 5 years of widespread clinical testing are reviewed.

Unusual monocyte-lymphocyte interactions determine the specificity of the immune-specific interferon response induced by Newcastle disease and herpes simplex viruses

Virus-induced immune-specific interferon (IS-IFN) is produced by previously sensitized peripheral blood mononuclear leukocytes (PBML) three to five days after they are placed in tissue culture. This IS-IFN is readily identified on the basis of its time of production and its synergistic composition of alpha and gamma interferons. The current studies demonstrate that circulating monocytes control the specificity and magnitude of the IS-IFN response. No IS-IFN is produced by PBML that are heavily depleted of monocytes. Immune-specific IFN production is enhanced in PBML cultures that are partially depleted of monocytes. Partial monocyte depletion permits virus to induce the production of IS-IFN by unsensitized PBML.

Herpes simplex virus-induced immunespecific interferon production by cryopreserved human peripheral blood mononuclear leukocytes

Peripheral blood mononuclear leukocytes (PBML) from 21 human donors seropositive for herpes simplex virus (HSV) type 1, and from seven seronegative donors were employed to produce interferon (IFN) in response to stimulation by HSV and phytohemagglutinin (PHA). Cryopreserved PBML produced titers of IFN, including immunespecific IFN, that were not significantly different from titers produced by freshly prepared PBML. In addition, cryopreserved PBML stored under conditions designed to simulate inter-institutional exchange of specimens produced quantities of IFN that did not vary significantly from quantities of IFN produced by cryopreserved cells that were stored under conventional conditions. Production of immunespecific IFN by cryopreserved cells represents an example of a measurement of cell-mediated immunity that is analogous in reliability and flexibility to currently available measurements of humoral immune responses.

Low incidence of serum neutralizing factors in patients receiving recombinant alfa-2b interferon (Intron A)

The development of serum neutralizing factors against recombinant alfa-2b interferon (Intron A) was reviewed in a large clinical experience. In 537 patients receiving systemic therapy, neutralizing factors developed in only 13 (2.4 percent). In 1,326 patients who received intranasal administration and 154 with intralesional administration, the incidence was less than 1 percent. Patients in whom antibody developed had no predisposing characteristics that could be identified, no particular types of patients with cancer had a high rate of neutralizing factors, and two of 10 patients with cancer in whom neutralizing factor developed were still able to show clinical responses. In patients in whom neutralizing factor was present, there was no discernible difference in the incidence or severity of interferon side effects as compared with patients who had no demonstrable neutralizing factor levels. This form of recombinant alpha-2 interferon appears to have a very low antigenic potential.

Immortalization of human T lymphocytes by HTLV-I: phenotypic characteristics of target cells and kinetics of virus integration and expression

In-vitro infection of normal human lymphocytes with HTLV-I (human T-cell lymphotropic retrovirus type I) has been carried out to study the target cell specificity and the kinetics of infection. Cord blood (CBL) and adult peripheral blood lymphocytes (PBL) have been co-cultivated with irradiated HTLV-I donor cells (MT2 and C91PL lines). Established ('immortalized') HTLV-I positive cell lines were obtained only from CBL: in comparison with PBL, a less mature phenotype of T-cell subsets and a lower interferon-gamma production was evidenced in CBL. A progressive variation of differentiation antigen representation and of exogenous T-cell growth factor (TCGF, interleukin-2, IL-2) medium concentration was observed with increasing time from infection. The four established lines obtained showed a predominant T3+, T4+, T8-, Tac+ phenotype and a reduced TCGF requirement. Studies on kinetics of HTLV-I infection showed that p19 and p24 viral antigens became expressed after a lag phase of 5 weeks. DNA Southern blot analysis indicated that a shift from polyclonal to monoclonal pattern of proviral integration occurred with time of culture, both complete and defective copies being transmitted from donor to recipient cells.

Functional properties in Sézary cells with an unusual phenotype

The immunological and functional characteristics of Sézary cells with an unusual phenotype are reported. The clinical, histologic, and hematologic picture was typical for Sézary syndrome. Studies with monoclonal antibodies showed that 80% Sézary cells had an CD3+, CD4+, CD5+, CD7-, CD8-, Leu-7+, Leu-8-, Leu-11-, OKM1- phenotype. By two-color immunofluorescence assay 80% FACS-sorted Leu-7+ cells coexpressed CD4 antigen and did not express the myeloid antigen OKM1, CD8, and antigens characteristic of immature T cells. The cells had no NK activity but did display a high helper activity. Unseparated and FACS-sorted Leu-7+ and Leu-7- Sézary cells did not respond to mitogens but were able to grow in the presence of exogenous IL-2. FACS sorted Leu-7- cells, cultured for 7 days in the presence of 20% IL-2, acquired the receptors for Leu-7. IL-2 and IFN-gamma production was studied in unseparated Leu-7+ and Leu-7- FACS-sorted Sézary cells. IL-2 production was lower than in normal cells. The addition of PHA or PHA plus TPA led to an increase in IL-2 production. Also IFN-gamma production was marked lower than in normal controls but increased after 7-day culture in exogenous IL-2. In conclusion in this case the Sézary cells may represent a neoplastic expansion of the CD3+, CD4+, CD5+, Leu-7+, Leu-11- subpopulation which is equivalent to the 2-4% of the Leu-7+ population in normal lymphocytes.

Immunostimulatory function of herpes simplex virus isolates from patients with frequent herpes labialis and a deficiency in immune-specific interferon production

Approximately 30% of persons with frequent episodes of herpes labialis are deficient in the production of HSV-induced immune-specific interferon (IFN) (Green, 1985). Herpes simplex virus (HSV) strains isolated from persons who make immune-specific IFN and from persons who do not make it were examined for their immunostimulatory capabilities. HSV isolated from the primary oral lesions of two patients deficient in immune-specific IFN production, one person with an intact immune-specific IFN response, HSV types 1 and 2 laboratory strains, and Newcastle disease virus (NDV) were added to cultures of peripheral blood mononuclear cells (PBML) from HSV seropositive donors. All HSV-isolates induced comparable titers of immune-specific IFN. These studies suggest that failure of some patients to develop an immune-specific IFN response is determined by the host, not the virus.

Immune-specific interferon production by peripheral blood mononuclear leukocytes from patients with primary and recurrent oro-labial herpes simplex virus infections

Immune-specific IFN (IFN) is produced by the peripheral blood mononuclear leukocytes (PBML) of greater than 95% of HSV-seropositive humans with infrequent recurrences of herpes labialis [Green, Yeh, and Overall, 1981]. However, herpes virus-induced immune-specific IFN was produced by PBML from only 33 of 48 (68.8%) persons with frequent recurrences (2-12 episodes a year). Two of eight subjects with primary herpes gingivostomatitis also failed to produce immune-specific IFN during either the acute or convalescent phases of their initial HSV infection. These data suggest that some persons have a defective immune-specific IFN response that exists from the time of their primary oro-labial HSV type 1 infection. This defect may predispose to a higher frequency of disease in some individuals.

Intranasal interferon-alpha 2 for prevention of natural rhinovirus colds

The prophylactic activity of intranasal human interferon-alpha 2 (HuIFN-alpha 2) against natural rhinovirus colds was determined in a randomized, double-blind, placebo-controlled trial. A total of 304 working adults self-administered sprays of HuIFN-alpha 2 (10(7) IU/day) or a placebo once daily. During 22 days of treatment, 13 (8.5%) placebo recipients but no HuIFN-alpha 2 recipients had respiratory illnesses documented secondary to rhinovirus infection (P = 0.0002). The occurrence of illness with symptoms of tracheobronchitis was lower in HuIFN-alpha 2 recipients (one eposide) than in placebo recipients (eight episodes, P = 0.04). In contrast, the frequency of nasal symptoms and the overall rate of respiratory illness were significantly higher in HuIFN-alpha 2 recipients during weeks 2 and 3 of treatment. Symptoms (obstruction, discomfort, blood-tinged nasal mucus) or signs (punctate bleeding sites, erosions, superficial ulcerations) of nasal irritation occurred in 40 HuIFN-alpha 2 recipients during week 3 (P less than 0.0001 versus placebo recipients). Although the results of the current study were partially confounded by the nasal side effects of prolonged administration, they showed that intranasal HuIFN-alpha 2 was efficacious in preventing rhinovirus colds under natural conditions.

Activity of human recombinant and lymphoblastoid interferons in human and heterologous cell lines

Three human alpha interferon (HuIFN-alpha) preparations currently being used in clinical trials, rIFN-alpha A, rIFN-alpha 2, and lymphoblastoid IFN (LYM-IFN) had appreciable activity against encephalomyocarditis and vesicular stomatitis viruses (VSV) in guinea pig transformed and guinea pig embryo cells, but not mouse L or rabbit kidney cells. The level of activity in guinea pig cells, compared with human WISH cells, was 182% (range 9%-1,900%). These results suggest that the guinea pig may be useful for testing the antiviral, anticancer, or immunomodulatory activity of Hu alpha IFNs in vivo.

Human polymorphonuclear neutrophil functions are unaffected by human interferon-alpha 2

Leukocyte-derived interferons have been reported to enhance the functions of polymorphonuclear neutrophils. This study reveals no effect of the highly purified recombinant DNA-produced human interferon-alpha 2 on the oxidative, chemotactic, adherent, phagocytic, and bactericidal activities of human polymorphonuclear neutrophils in vitro.

Influenza vaccination and theophylline pharmacokinetics in patients with chronic obstructive lung disease

Total Theophylline clearance rate was measured before and 24 hours after standard influenza vaccination in seven men with stable chronic obstructive lung disease. In four, total theophylline clearance rate was also measured 48 hours after vaccine administration. There was no significant change in the clearance rate after either time interval. These results do not support recent recommendations to monitor serum theophylline concentrations or reduce theophylline dosage during the 48-hour period following influenza vaccination. Nevertheless, pending further studies, patients maintained on a regimen of theophylline preparations should be followed clinically for theophylline toxicity for the first several days after receiving influenza vaccine.

Automated cytopathic effect (CPE) assays

An automated CPE procedure has been developed that increases the precision and ease of performing titrations of measles, mumps and rubella viruses in vaccine materials. By this procedure, additions of cell suspensions and reagents and the dilution of samples are performed automatically by a modified Dynatiter instrument, using 96-well microtitre plates. Cell monolayers are stained with carbolfuchsin dye to eliminate the need for microscopic examination. Finally, the trays are read in an optical scanner and the end points calculated automatically by a programmable calculator. The increased accuracy and precision attained by performing greater numbers of replicate assays at reasonable cost will be of particular value to vaccine manufacturers.