Administration Of Interferons Research Articles

Mechanisms for regulation of cellular responsiveness to human IFN-beta1a.

Interferons (IFNs) are potent, pleiotropic cytokines, and therefore it is likely that the cell has mechanisms to modulate IFN activity in response to excessive or prolonged IFN exposure. To investigate this question, Jurkat T cells were exposed to IFN-beta1a in vitro. The effect of dose and frequency of IFN treatment on receptor expression, the signal transduction pathway, and biologic activity was examined. Results demonstrate that at even modest doses of IFN (60 IU/ml), cell surface expression of the IFN receptor subunit, IFNAR-1, decreased significantly, and the cells were unresponsive to further IFN treatment. More interestingly, after an initial treatment with very low concentrations of IFN (<10 IU/ml), even when receptor levels remained normal and phosphorylation of signaling molecules occurred, cells were still refractory to further IFN treatment. After withdrawal of IFN, full cellular responsiveness was a progressive but surprisingly slow process. Cells retreated 2 days or 4 days after the initial IFN treatment were still refractory to even high doses (500 IU/ml) of IFN. Cells retreated 1 week after the initial IFN treatment were fully responsive. High levels of Stat1 and Stat2 correlated with the block in transcriptional activation of IFN-dependent genes and may be a mechanism by which cells can downmodulate an IFN response. Similar results were obtained when fresh peripheral blood mononuclear cells (PBMC) were treated with IFN and expression of the endogenous IFN-dependent gene, MxA, was examined. Cell surface levels of IFNAR-1 decreased and Stat1 levels increased after IFN-beta treatment, and retreatment with IFN resulted in an attenuated induction of Mx protein expression. In the context of using IFNs as therapeutic agents in the treatment of human disease, our data suggest that increasing the amount or frequency of IFN administration may not yield desired biologic effects. Thus, issues concerning the dosage and the frequency of IFN-beta administration deserve careful consideration.

Apo2L/TRAIL and Bcl-2–related proteins regulate type I interferon–induced apoptosis in multiple myeloma

It has been reported that interferons (IFNs) may have antitumor activity in multiple myeloma (MM). The mechanism for their effect on MM, however, remains elusive. This study shows that IFN-alpha and -beta, but not -gamma, induce apoptosis characterized by Annexin V positivity, nuclear fragmentation and condensation, and loss of clonogenicity in 3 MM cell lines (U266, RPMI-8266, and NCI-H929), and in plasma cells from 10 patients with MM. Apo2 ligand (Apo2L, also TRAIL) induction was one of the earliest events following IFN administration in U266 cells. Treatment of these cells with TRAIL, but not with Fas agonistic antibodies, induces apoptosis. Cell death induced by IFNs and Apo2L in U266 cells was partially blocked by a dominant-negative Apo2L receptor, DR5, demonstrating the functional significance of Apo2L induction. This study shows that IFNs activate caspases and the mitochondrial-dependent apoptotic pathway, possibly mediated by Apo2L production. Thus, IFN-alpha and -beta induce cytochrome c release from mitochondria starting at 12 hours, with an amplified release seen at 48 hours. Moreover, Bid cleavage precedes the initial cytochrome c release, whereas the late, amplified cytochrome c release coincides with changes in levels of Bcl-2, Bcl-X(L), and reduction of mitochondrial membrane potential. These results link the Apo2L induction and modulation of Bcl-2 family proteins to mitochondrial dysfunction. Furthermore, IFNs and Apo2L induce cell death of CD38(+)/CD45(-/dim) plasma cells, without significant effect on nonplasma blood cells, in a caspase and Bcl-2 cleavage-dependent manner. These results warrant further clinical studies with IFNs and Apo2L in MM.

γ-aminobutyric acid-transaminase activity in the human thymus after administration of interferons

The purpose of this article is to study the amounts of γ-aminobutyric acid-transaminase (GABA-t) during immune response in the human thymus. GABA-t was studied by biochemical and histochemical methods in 7 immunostimulated (treated) and 7 non-immunostimulated (untreated) patients (4 young adult, age range: 24–36 years; 3 older adult, age range: 56–66 years). Immunostimulation was performed using interferon drugs for 6 months. After the histoenzymatic staining of GABA-t activity, the slides containing the samples of thymus of treated and untreated patients underwent quantitative analysis of images. The present results provide direct evidence that the immune response increases the level of GABA-t contained in vessels, parenchyma and nerve fibers of the thymus. Treatment with interferon is also capable of increasing the protein content of the thymus. The biochemical data together with the histoenzymatic results provide evidence for a localization of GABA-t in the thymic gland. Moreover, γ-aminobutyric acid can be considered as one of the linking molecules between the immune and nervous functions of the human thymus.

Immunoadjuvant activities of E. coli- and plasmid-expressed recombinant chicken IFN- α/ β, IFN- γ and IL-1 β in 1-day- and 3-week-old chickens

In the present study we assessed the capacity of recombinant E. coli- or plasmid-expressed chicken interferons (IFN) and chicken IL-1 β, to exert immunostimulatory activities for humoral immune responses, in day-old and adult chickens. We observed that both recombinant E. coli-expressed chicken IFN- α/ β and IFN- γ facilitated the induction of a primary and also a secondary antibody response, using tetanus toxoid (TT) as a bacterial model antigen, in immunologically mature 3-week-old chickens. In contrast, no improvement of antibody responses were noted when either type of chicken IFN was co-injected with inactivated Infectious Bursal Disease Virus (IBDV) antigen. TT-specific antibody formation was marginally increased by co-injection of recombinant E. coli-expressed chicken IL-1 β. Combined administration of IFN- α/ β plus IFN- γ or IL- β increased responses to TT in an additive, but not synergistic fashion. Remarkably, no augmentation of antibody responses specific for TT, nor IBDV, was noted in day-old birds, receiving IFN- α/ β or IFN- γ as adjuvant. Also, intramuscular immunization of 3-week-old birds, using plasmids encoding IFN- α/ β together with TT protein antigen, significantly increased the speed and magnitude of TT-specific antibody responses. Plasmids encoding chicken IL- β or IFN- γ had a minimal or inhibitory effect, respectively. These data indicate a potential for chicken cytokines as immunoadjuvant for particular types of chicken vaccine antigens.

Orally administered IFN-alpha acts alone and in synergistic combination with intraperitoneally administered IFN-gamma to exert an antitumor effect against B16 melanoma in mice.

Administration of interferons (IFN) via the intranasal route recently has been shown to exert an antitumor activity against a variety of tumors in mice, including B16 melanoma inoculated intravenously. This study confirms the antitumor activity of orally administered IFN-alpha against B16 melanoma challenge using another route of tumor inoculation, the intraperitoneal route. It further demonstrates that orally administered IFN-alpha can synergistically interact with intraperitoneally administered IFN-gamma but not with intraperitoneally administered IFN-alpha. The results support the interpretation that the oral route may provide an effective alternative or supplement to current methods of IFN administration for the control of malignancies.

The effects of prednisolone and interferons on serum macrophage colony stimulating factor concentrations in chronic hepatitis B

Backgrounds/Aims: Serum concentrations of macrophage-colony stimulating factor (M-CSF) are increased in parallel with hepatic inflammation. The aim of this study was to assess the immunologic significance of elevated M-CSF in patients with chronic hepatitis B virus infection. Methods: The subjects included 20 asymptomatic HBV carriers and 45 patients with chronic hepatitis B, including 8 undergoing prednisolone treatment, 10 experiencing an acute exacerbation, and 12 undergoing daily administration of interferons. Results: Serum concentrations of M-CSF significantly decreased during prednisole administration, but significantly increased following prednisolone withdrawal, similar to the increase during acute exacerbation. Changes in the lipopolysaccharide-stimulated production of interleukin-1-beta and tumor necrosis factor-alpha by peripheral whole blood, or of interferon-gamma by peripheral blood mononuclear cells showed a similar pattern. Serum concentrations of M-CSF did not correlate with the titers of HBV-DNA or HBV-DNA polymerase activity. However, serum M-CSF peaked preceding seroconversion to HBe antibody in three HBe antigen positive patients. Exogenous interferon-alpha, -beta, or -gamma induced significant elevation in serum in M-CSF concentrations, irrespective of changes in the serum alanine aminotransferase levels. Conclusions: Increased serum M-CSF is closely associated with increased serum interfersons and/or proinflammatory cytokines produced by peripheral blood cells during hepatic inflammation in chronic hepatitis B. This may be a consequence of the altered cytokine cascade resulting from the host immune response against hepatitis B virus.

Interferon gamma down-regulates cytochrome P450 3A genes in primary cultures of well-differentiated rat hepatocytes

Abstract Administration of interferons of both the gamma and alfa/beta classes down-regulates hepatic cytochrome P450 (CYP) genes when administered to humans or rats. In male rats, interferons decrease expression of CYP3A2 at a pretranslational level, but because interferons also release other cytokines in vivo, it is unclear whether this is a direct effect on hepatocytes. We therefore examined the effects of rat recombinant interferon gamma (IFN-gamma) on CYP3A2, other 3A genes, and 2C11 in stable primary cultures of male rat hepatocytes. Hepatocytes were cultured on matrigel in Williams' E, and messenger RNAs (mRNAs) for 3A2, 3A1-like CYPs, and 2C11 mRNA were determined by RNase protection assays. CYP3A and 2C11 proteins were immunoquantified, and their catalytic activities were estimated by testosterone hydroxylation pathways. In control cells, 3A2 mRNA decreased initially but then recovered, and stable levels (15% of freshly isolated cells) were attained between days 3 and 7. Phenobarbital increased 3A2 mRNA to 60-120% values of freshly isolated cells, and mRNA for 3A1-like CYPs were increased 20-fold. In both control and phenobarbital-treated hepatocytes, rat recombinant IFN-gamma (33 U/mL) reduced mRNA for 3A2 and 3A1-like CYPs, as well as 3A protein and testosterone 6 beta-hydroxylase activity. Interferon had no effect on CYP2C11 at mRNA or protein levels in untreated cells, although a reduction in 2C11 protein was evident in phenobarbital-treated cultures. It is concluded that interferon directly alters expression of constitutive and inducible CYP3A genes in well-differentiated male rat hepatocytes in culture, but has no effect on constitutive expression of CYP2C11. (Hepatology 1996 Aug;24(2):367-73)

Interferon ? down-regulates cytochrome P450 3A genes in primary cultures of well-differentiated rat hepatocytes

Administration of interferons of both the gamma and alfa/beta classes down-regulates hepatic cytochrome P450 (CYP) genes when administered to humans or rats. In male rats, interferons decrease expression of CYP3A2 at a pretranslational level, but because interferons also release other cytokines in vivo, it is unclear whether this is a direct effect on hepatocytes. We therefore examined the effects of rat recombinant interferon gamma (IFN-gamma) on CYP3A2, other 3A genes, and 2C11 in stable primary cultures of male rat hepatocytes. Hepatocytes were cultured on matrigel in Williams' E, and messenger RNAs (mRNAs) for 3A2, 3A1-like CYPs, and 2C11 mRNA were determined by RNase protection assays. CYP3A and 2C11 proteins were immunoquantified, and their catalytic activities were estimated by testosterone hydroxylation pathways. In control cells, 3A2 mRNA decreased initially but then recovered, and stable levels (15% of freshly isolated cells) were attained between days 3 and 7. Phenobarbital increased 3A2 mRNA to 60-120% values of freshly isolated cells, and mRNA for 3A1-like CYPs were increased 20-fold. In both control and phenobarbital-treated hepatocytes, rat recombinant IFN-gamma (33 U/mL) reduced mRNA for 3A2 and 3A1-like CYPs, as well as 3A protein and testosterone 6 beta-hydroxylase activity. Interferon had no effect on CYP2C11 at mRNA or protein levels in untreated cells, although a reduction in 2C11 protein was evident in phenobarbital-treated cultures. It is concluded that interferon directly alters expression of constitutive and inducible CYP3A genes in well-differentiated male rat hepatocytes in culture, but has no effect on constitutive expression of CYP2C11.

The Role of Inflammatory Mediators on Hepatitis B Virus Surface Expression in A Transgenic Mouse Model

We have recently reported that administration of recombinant tumor necrosis factor–alpha to hepatitis B virus transgenic mice reduces the hepatic steadystate content of HBV–specific mRNA by up to 80% in the absence of liver cell injury. In the current study, we analyzed the regulatory effects of several other inflammatory cytokines in the same transgenic model system. Hepatic HBV mRNA content was reduced by up to 90% following administration of a single noncytopathic dose (100,000U) of interleukin–2. Comparable effects were produced by administration of alpha and beta interferons, but only after multiple injections of at least 500,000U per mouse. Importantly, the regulatory effect of IL–2 was completely blocked by the prior administration of antibodies to tumor necrosis factor–α, which did not block the effect of IFN–α or IFN–β. In contrast to these observations, recombinant IFNg, IL–1, IL–3, IL–6, TNF–β, transforming growth factor–β and granulocyte–monocyte colony stimulating factor were inactive in this system. These results suggest that selected inflammatory cytokines can down–regulate HBV gene expression in vivo by at least two pathways, one that is dependent on TNF–α and another that is not. These results imply that antigen–nonspecific products of the intrahepatic HBV–specific inflammatory response may contribute to viral clearance or persistence during HBV infection.

Interleukin-2 and alpha/beta interferon down-regulate hepatitis B virus gene expression in vivo by tumor necrosis factor-dependent and -independent pathways.

We have recently reported that administration of recombinant tumor necrosis factor alpha (TNF-alpha) to hepatitis B virus (HBV) transgenic mice reduces the hepatic steady-state content of HBV-specific mRNA by up to 80% in the absence of liver cell injury. In the current study, we analyzed the regulatory effects of several other inflammatory cytokines in the same transgenic model system. Hepatic HBV mRNA content was reduced by up to 90% following administration of a single noncytopathic dose (100,000 U) of interleukin 2 (IL-2). Comparable effects were produced by administration of alpha and beta interferons (IFN-alpha and IFN-beta), but only after multiple injections of at least 500,000 U per mouse. Importantly, the regulatory effect of IL-2 was completely blocked by the prior administration of antibodies to tumor necrosis factor alpha (TNF-alpha), which did not block the effect of IFN-alpha or IFN-beta. In contrast to these observations, recombinant IFN-gamma, IL-1, IL-3, IL-6, TNF-beta, transforming growth factor beta, and granulocyte-monocyte colony-stimulating factor were inactive in this system. These results suggest that selected inflammatory cytokines can down-regulate HBV gene expression in vivo by at least two pathways, one that is dependent on TNF-alpha and another that is not. These results imply that antigen-nonspecific products of the intrahepatic HBV-specific inflammatory response may contribute to viral clearance or persistence during HBV infection.

Treatment with interferon for genital HPV in HIV-positive and HIV-negative women

The administration of interferons can be resorted to, either on its own or in combination with physical destruction methods, when the extent of genital HPV is widespread. Extensive genital HPV involvement is often seen in HIV-positive patients as a consequence of their immunodeficiency. The extension of these lesions may invalidate treatment by physical destruction, while an underlying immunodeficiency renders interferon therapy less efficacious. We studied HIV-positive and HIV-negative patients with a similar HPV involvement of their genital tract and compared the effectiveness of systemically administered α 2 b and β interferons in clearing HPV. Our results confirm that interferon therapy will cure most patients with extensive genital HPV when they are HIV-negative. HIV-positive patients with CD4 counts over 400 lymphocytes/mm 3 may expect a similar cure rate, but this halves when this critical threshold is crossed. In these severely immunodeficient patients repeated courses of interferon therapy alone or in combination with physical destruction methods may be required to cure HPV infection.

A disturbance of interferon synthesis with the hyperproduction of unusual kinds of interferon can trigger autoimmune disease and play a pathogenetic role in AIDS: The removal of these interferons can be therapeutic

Disturbances of interferon synthesis with the hyperproduction of unusual kinds of interferons may be the initial step which triggers autoimmune disease through a chain of pathological reactions including the disturbances of several immunological and cytokine cascades. Prolonged circulation of this interferon may be a predictive marker of an autoimmune condition; the administration of interferons to animals or humans with autoimmune disease or an underlying or latent autoimmune condition can exacerbate or trigger the disease. Healthy people do not have interferon in their blood. This fundamental disturbance of interferon synthesis can result either from a genetic predisposition or from the influence of certain viruses (or viral particles) or both factors together. AIDS has many features similar to autoimmune disease, including the hyperproduction of aberrant interferon, a type with restricted anti-HIV activity, protectively induced by HIV to allow its continued replication and survival. This interferon stimulates the production of certain cytokines and autoantibodies which help unleash the potentially self-destructive powers of the immune system, bringing immunological chaos. In other words, while usual viruses induce normal interferon, which protects the cells against viral infection, HIV induces an abnormal, defective kind of interferon which ensures virus survival. Since there is no known effective method of destroying HIV directly, removing links in this chain of reactions could indirectly destroy HIV and possibly help restore immune functioning. The neutralization of hyperproduced interferons, certain other cytokines and some autoantibodies and autoantigens by injected polyclonal or monoclonal antibody produced preferably in human hybridoma, removal via extracorporeal means, or the use of pharmaceutical agents which dampen the production or biological activity of these factors can be a therapeutic approach to the management of these chronic diseases.

Orally Administered Interferons Suppress Bone Marrow Function

The accepted routes of interferon (IFN) administration in clinical applications are intramuscular, subcutaneous, intraperitoneal, intratumor, and intravenous. Recently, oral administration of interferons has been shown to cause a suppression of peripheral white blood cell (WBC) counts. Moreover, orally administered interferons mediate their peripheral WBC suppression via a different mechanism than that of intraperitoneally administered interferons. This study extends the previous studies to show that the peripheral WBC suppression induced by oral interferon treatment reflects an actual bone marrow suppression. The bone marrow-suppressive effects of orally and subcutaneously administered recombinant human IFN-alpha A/D (rHuIFN-alpha A/D) have been partially characterized in kinetics studies and compared with the peripheral WBC-suppressive effects of orally and subcutaneously administered rHuIFN-alpha A/D. Oral and subcutaneous administrations of rHuIFN-alpha A/D cause a significant suppression of peripheral WBC counts with 1 day of rHuIFN-alpha A/D administration. This suppression reaches its maximum level with 3 days of rHuIFN-alpha A/D administration and plateaus over a 12-day treatment time. Similarly, oral and subcutaneous administrations of rHuIFN-alpha A/D cause a significant suppression of bone marrow function with 1 day of rHuIFN-alpha A/D administration. This suppression reaches its maximum level with 3 days of rHuIFN-alpha A/D administration and plateaus over a 12-day treatment time. Thus, the WBC-suppressive and bone marrow-suppressive effects of rHuIFN-alpha A/D administered either orally or subcutaneously parallel each other. The peripheral WBC-suppressive activities of orally and subcutaneously administered rHuIFN-alpha A/D diminish at the same rate, after cessation of rHuIFN-alpha A/D treatment. Peripheral WBC suppression is lost by 5 days after cessation of rHuIFN-alpha A/D treatment. The mechanisms by which orally and subcutaneously administered interferons exert their bone marrow-suppressive effects differ, however. Bone marrow suppression mediated by subcutaneous administration of murine IFN-alpha/beta (MuIFN-alpha/beta) is blocked by the presence of circulating antibodies to MuIFN-alpha/beta. In contrast, the bone marrow suppression mediated by oral administration of MuIFN-alpha/beta occurs even in the presence of circulating antibodies to MuIFN-alpha/beta. These results continue to support a potential clinical role for oral administration of interferons, particularly for the control of diseases of myelogenous origin.

A disturbance of interferon synthesis with the hyperproduction of unusual kinds of interferon can trigger autoimmune disease and play a pathogenetic role in AIDS: The removal of these interferons can be therapeutic

Disturbances of interferon synthesis with the hyperproduction of unusual kinds of interferons may be the initial step which triggers autoimmune disease through a concatenation of pathological reactions including the disturbance of several immunological and interferon cascades. This fundamental disturbance can result either from a genetic predisposition or from the influence of certain viruses (or viral particles) or both factors together. The administration of interferons to individuals with an underlying or latent autoimmune condition can exacerbate or trigger the disease. AIDS has many features similar to autoimmune disease, including the hyperproduction of aberrant interferon, a type with little or no anti-HIV activity, protectively induced by HIV to allow its continued replication and survival. In other words, while most viruses induce normal IFN which protects the cells against viral infection, HIV induces an abnormal, defective kind of IFN which insures viral survival. The neutralization of hyperproduced interferons by polyclonal or monoclonal antibody produced in mouse, or preferably, human hybridoma, removal via extracorporeal means, or the use of antagonists which diminish the production or biological activity of these interferons can be a therapeutic approach to the management of these chronic diseases. In addition, the extracorporeal removal of different kinds of interferons, autoantibodies, autoantigens and other substances from the organism in certain pathological conditions may be an effective and safe method of treatment for autoimmune diseases and AIDS.

Interferons and central regulation of feeding.

Interferons (IFNs) are immunomodulators with neuromodulatory activities. To study the effects of IFNs on the central regulation of feeding, rats were subjected to various applications. The results show the following. 1) Intracerebroventricular microinfusion of rat IFN (15-225 IU/rat) decreased short-term (2-h) food intake in rats. Computerized analysis of behavioral patterns demonstrated a reduction of meal size and meal duration, whereas meal frequency slightly increased. Nighttime and total daily food intakes were not significantly affected. 2) Short-term food intake suppression by intracerebroventricular rat IFN was accompanied by a small increase in cerebrospinal fluid and rectal temperatures. 3) Intracerebroventricular microinfusion of heat-treated rat IFN or of recombinant human interferon-alpha (rhIFN-alpha) did not affect food intake. Only one dose of rhIFN-gamma (400 ng/rat) decreased 2-h food intake. These results are consistent with the species specificity to the effects of IFNs. 4) Peripheral administration of rat IFN in doses equivalent to those administered centrally had no effect on food intake. The results suggest that IFN acts directly in the central nervous system to decrease short-term feeding.

Scar wars strategies. Target collagen.

Hypertrophic scarring and keloid formation are clinical problems with effectively limited solutions. Although numerous methods have been devised to combat them, this article focuses on promising pharmacologic strategies that target collagen metabolism. Laboratory investigations of amino-acid analogs, procollagen peptides, D-penicillamine, and pentoxifylline have demonstrated them to be effective inhibitors of collagen synthesis in cultured cells and/or in animal models. Clinical trials of intralesional administration of interferons have shown impressive reductions in the size and collagen production of keloids. Furthermore, interference of extracellular matrix-enhancing cytokines, such as TGF-beta, may be an effective solution to keloids and hypertrophic scars. Additional research of soluble cytokine receptors, autoantibodies to cytokines, cytokine receptor antagonists, and cytokine-binding molecules may lead to the development of better therapeutic agents.

Flow cytometric analysis of antineoplastic effects of interferon-?, ? and ? labelled with fluorescein isothiocyanate on cultured brain tumors

Antineoplastic effects of interferons (IFNs) on brain tumors have often been reported in the literature, however, so far as we know, there are no reports of the study on the antineoplastic effect of IFNs (alpha, beta, and gamma) labelled with fluorescein isothiocyanate (FITC) using flow cytometry (FCM). Three established glioma cell lines and 11 cultured cells of brain tumor from surgical specimens were exposed to IFN-alpha, beta, and gamma at the concentrations of 10(2)-10(5) IU/ml for 24 h, respectively. Using FCM, the viability of the cells was evaluated with fluorescein diacetate stain and the cell cycle was analyzed from the DNA-histogram with propidium iodide stain. Furthermore, FITC-labelled IFN-alpha, beta and gamma were also contacted with each cell to calculate respective positive cells. The viability decreased about 60% on day 1 and day 3, indicating the effect of IFN-alpha and beta on U373MG cells and on some cultured glioma cells from surgical materials, whereas, IFN-gamma had no effects. Antineoplastic effect of each IFN well correlated with FITC-positive rates, demonstrating S phase block in the cell cycle. IFN-gamma had no antineoplastic effects, whereas IFN-alpha and beta showed antineoplastic effects, which fact suggested that IFN-gamma receptor be different from those of IFN-alpha and beta. The method of FITC-labelling for IFNs with the aid of FCM has the advantages as follows: 1) Antineoplasticity of IFN can be simply evaluated with FCM; 2) It is easy to analyze the action mechanism of IFN; 3) Information on the receptor is obtainable; and 4) Sensitivity can be evaluated prior to administration of IFN, suggesting possibilities of clinical application of this method.

Modulation of Peripheral Leukocyte Counts in Mice by Oral Administration of Interferons

The ability of interferons (IFN) to exert a systemic effect following their oral administration was evaluated. One systemic effect of parenteral interferon administration has been shown to be a suppression of the number of peripheral white blood cells both in man and in mouse models. Using the mouse model of peripheral white blood cell suppression, the relative systemic effects of orally and subcutaneously administered interferons were determined. Murine IFN-beta, murine IFN-gamma and cross-reactive recombinant human IFN-alpha A/D were examined. The oral administrations of each of the three interferons were found to cause a dose-dependent suppression of the peripheral white blood cell counts. Significant levels of suppression were seen with as little as 5 units/day of murine IFN-beta and with 500 units/day of recombinant human IFN-alpha A/D and murine IFN-gamma. The dose-response curves obtained with orally administered interferons were much more shallow than those obtained with subcutaneously administered interferons. The results demonstrate that oral administration of interferons can provide a significant systemic effect. Further, the results support the possibility that the oral administration of interferons may have therapeutic potential.

Basal and Interferon-Induced 2′,5′-01igoadenylate Synthetase in Human Monocytes, Lymphocytes, and Peritoneal Macrophages

2',5'-Oligoadenylate (2-5A) synthetase is an intracellular enzyme induced during viral diseases and after clinical administration of interferons (IFN). Because monocytes and T and B lymphocytes in peripheral blood are targets of viral infection, we compared the basal levels and induction of 2-5A synthetase activity in these three cell types. IFN-beta induced significant, three- to eightfold increases in 2-5A synthetase activity in monocytes and T and B lymphocytes, both in vitro and in vivo. IFN-gamma was less effective in inducing 2-5A synthetase than IFN-beta, yielding up to 2.6-fold increases in monocytes and slight increases in lymphocytes in vitro. IFN-beta also had greater 2-5A synthetase-inducing activity than IFN-gamma in HL-60 and U937 monocytic cell lines and in human peritoneal macrophages. Baseline levels of 2-5A synthetase in untreated peripheral blood monocytes separated by adherence or density gradients were three- to fivefold higher than in lymphocytes. 2-5A synthetase levels were twofold higher in B than in T lymphocytes separated by fluorescence-activated cell sorting. Tumor necrosis factor-alpha (TNF-alpha) did not induce this enzyme in peripheral blood mononuclear cells (PBMCs) or peritoneal macrophages. Thus, monocytes had greater basal and induced levels of 2-5A synthetase activity than did lymphocytes and contributed disproportionately to total 2-5A synthetase activity in peripheral blood.

The Potential Role of Interferons and Interferon Antagonists in Inflammatory Disease

Studies indicate that, among a number of other cytokines, interferons (IFN alpha, beta and gamma) are important elements regulating acute as well as chronic inflammatory responses. The role of interferons has been investigated in various experimental models of inflammation, by administration both of interferons and of antibodies that block the biological activity of interferons formed endogenously. The conclusions reached from these experiments clearly indicate that interferons can boost as well as inhibit inflammation. The effects depend on the type of inflammation studied, the time of interferon administration or emergence in the tissue, the type of interferon (alpha/beta or gamma), the dosage, and the presence of other inflammation-controlling cytokines. The effect of blockage of IFN gamma by the systemic administration of neutralising antibodies is particularly clear. Such blockage has been found to profoundly modify local lipopolysaccharide (LPS)-induced inflammation, brain inflammation due to autoimmunity or infection, and shock reactions caused by systemic administration of LPS. Further research on the particular place occupied by interferons in the inflammation-controlling cytokine network holds great promise, not only for better understanding but also for improved therapy of acute and chronic inflammatory disease.