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Interferon induction by viruses. XIII. Detection and assay of interferon induction-suppressing particles.

An assay is described for detecting and measuring the capacity of a single virus particle to suppress completely the yield of interferon from a cell otherwise competent to product interferon. The assay defines virus populations in terms of a newly quantifiable attribute--interferon induction-suppressing particles (ISP). The antagonistic actions of interferon-inducing particles and interferon induction-suppressing particles are thought to determine the interferon-inducing capacity intrinsic to a virus population.

Animals↗

Chicken macrophage activation by interferon: do birds lack the molecular homologue of mammalian interferon-gamma?

In mammalian species, interferon-gamma (IFN-gamma) is a lymphokine with a wide range of biological effects, of which the antiviral and macrophage-activating capacities are those best characterized. In birds, no equivalent with a similar range of actions has as yet been isolated. Chicken splenocytes were stimulated by mitogens in conditions that were similar to those used for the induction of mammalian IFN-gamma. Culture fluids were assayed for antiviral and macrophage-activating capacities. As much as 1000 units/ml of an interferon-like antiviral activity was found in the culture fluid of Staphylococcus aureus lysate-induced spleen cells. Seroneutralization assays with a polyclonal antiserum against purified interferon and physicochemical studies revealed that the antiviral activity is identical to or closely related to type I interferon (interferon-alpha/beta). The presence of macrophage activating factors (MAF) in the splenocyte medium was demonstrated by measuring increased production of H2O2 by chicken peritoneal macrophage cultures and a chicken macrophage cell line (HD11). The heat stability of this MAF activity was similar to that of the antiviral factor, and was completely neutralized by the anti-IFN-alpha/beta antiserum. These results show that when the classical procedure used for the production of mammalian IFN-gamma is applied to chicken splenocytes, it does not yield an equivalent for IFN-gamma/MAF. This suggests that the classification of interferons into types (alpha, beta and gamma), while generally applicable in mammals, may not be applicable in birds.

Animals↗

Interferon-alpha and interferon-gamma production capacity of idiopathic isolated optic neuritis patients.

Interferon-alpha and interferon-gamma production by idiopathic isolated optic neuritis (ON) patients was studied. The production capacity was compared with that in two control groups: patients with iritis and healthy control subjects. A sensitive and reliable interferon bioassay was applied for interferon level measurements. Statistically significant differences were not found between patients and control groups in either interferon-alpha production or interferon-gamma production.

Adult↗

Evaluation of long-term efficacy of interferon alpha-2b and ribavirin in combination in naive patients with chronic hepatitis C: an Italian multicenter experience. Ribavirin-Interferon in Chronic Hepatitis Italian Group Investigators.

BACKGROUND/AIMS: A combination of interferon alpha and ribavirin has been suggested to reach a higher rate of sustained virological response in patients with chronic hepatitis C than monotherapy. In this study we assessed the long-term efficacy of this combination therapy in the treatment of selected Italian naive chronic hepatitis C patients compared to interferon alpha monotherapy. METHODS: We enrolled 428 naive patients who were randomly assigned to receive either recombinant interferon alpha-2b and ribavirin for 24 weeks or interferon alpha-2b alone for 48 weeks. The primary end-point of the study was the rate of sustained virological response. Serum HCV RNA levels were determined before treatment; during treatment at weeks 12 and 24 in the patients receiving the combination therapy; at weeks 12, 24, 36 and 48 in the patients receiving monotherapy; and after therapy at weeks 12, 24 and 48 in the patients in both study groups. RESULTS: Sustained virological response was observed in 43% of the patients treated with combination therapy and in 14% of the patients treated with monotherapy. Logistic regression analysis showed that sustained response was associated with the combination therapy, with HCV genotype other than 1b, with an HCV viral load of 3x10(6) copies/ml or less, with an inflammation score of 7 or less, and with an estimated duration of disease of 10 years or less. CONCLUSIONS: A 24-week treatment course with interferon alpha-2b and ribavirin offers a greater chance of sustained virological response compared to treatment with interferon alpha-2b alone for 48 weeks, and may be indicated as initial therapy in such patients.

Adult↗

Impact of high-dose interferon induction and ribavirin therapy in patients with chronic hepatitis C relapsing after or not responding to interferon monotherapy.

BACKGROUND/AIMS: Initial high-dose interferon-alpha induction therapy in combination with ribavirin improves sustained response rates in treatment-naïve patients. This prospective, randomized, controlled study tested whether non-responders or relapsers to interferon monotherapy also benefit from induction therapy. METHODS: Patients with chronic hepatitis C who had not responded to (n=75) or relapsed (n=80) after previous interferon therapy were randomized to receive three different interferon doses during the first 14 weeks of therapy (A: 10 MU IntronA/day for 2 weeks, followed by 10 MU/2 days for 12 weeks; B:5 MU/d for 14 weeks; C: 5 MU/2 days for 14 weeks) followed in all by 5 MU/2 days for 24 weeks. All patients received 1-1.2 g ribavirin/day throughout the whole study. RESULTS: The rates of viral clearance at any time on treatment were similar in all groups. Sustained response rates were also not different among the groups in interferon nonresponders (A 32%, B 29%, C 31%) and relapsers (A 64%, B 68%, C 71%), respectively, as well as in patients with different genotypes. As expected, sustained response rates were higher in patients with genotype non-1 than in those with genotype 1. CONCLUSION: High-dose induction therapy does not improve the outcome of interferon/ribavirin therapy in interferon nonresponders or relapsers.

Administration, Oral↗

Interferon alfa-2b plus ribavirin for chronic hepatitis C patients who have not responded to interferon monotherapy.

BACKGROUND: The role of combination therapy is poorly defined in chronic hepatitis C patients who are non-responders to interferon. AIM: To assess the efficacy, safety and tolerance of interferon alfa-2b plus ribavirin in chronic hepatitis C patients who do not respond to interferon monotherapy. METHODS: A total of 127 non-responder patients with chronic hepatitis C received 3 mU t.i.w. of interferon alfa-2b plus 1000-1200 mg ribavirin daily for 48 weeks. Effects of therapy were evaluated by serum aminotransferases and hepatitis C virus (HCV) RNA levels. RESULTS: Twenty-nine (23%) patients had an end-of-treatment response. Six months after treatment, 20 (16%) patients were sustained responders. Early loss of HCV RNA was the strongest predictor of a sustained response (P < 0.0001). Remission was also more frequent in patients with genotype 1b (P < 0.02), elevated alanine aminotransferase (P < 0.03) and low gamma glutamiltranspeptidase (P < 0.002). Treatment was discontinued in 21 (17%) patients: in 14 for intolerance and in seven due to side-effects. CONCLUSIONS: Combination therapy with interferon plus ribavirin produced a sustained response in 16% of chronic hepatitis C patients who were non-responders to interferon. This combination was safe and well tolerated.

Adult↗

Comparison of treatments of chronic hepatitis B in children with lamivudine and alpha-interferon combination and alpha-interferon alone.

BACKGROUND: The aim of this study was to compare the efficacy of the alpha-interferon treatment with treatment using alpha-interferon and lamivudine in combination for cases of childhood chronic hepatitis B infection. METHODS: Patients were evaluated in two groups retrospectively. In group 1, 27 patients were simultaneously given alpha-interferon 2b 10 MU/m2, 3 days a week by s.c. injection plus lamivudine 4 mg/kg a day (maximum 100 mg) for 12 months. In group 2, there were 13 patients who only received the same dosage of alpha-interferon and no lamivudine over the same period of time. RESULTS: In group 1 the initial mean value of alanine aminotransferase (ALT) was 121 +/- 66 IU/L and decreased to 27.8 +/- 11.5 IU/L; in group 2, initial mean values of ALT was 129 +/- 46 IU/L and decreased to 60 +/- 6 IU/L at the end of the twelfth month of the therapy (P < 0.05). Hepatitis B virus DNA (HBV-DNA) clearance was obtained in all group 1 patients and six of 13 patients in group 2 at the end of the therapy (P < 0.001). The rates of hepatitis B early (HBe) antigen clearance and anti-HBe seroconversion were 59 and 37% in group 1 and 46 and 30.7% in group 2 (P > 0.05). The number of patients with complete response was found to be 10 out of 27 (37%) in group 1 and four out of 13 cases (30.7%) in group 2, 6 months after the end of the therapy. There was no statistically significant difference between both groups (P > 0.05). CONCLUSION: alpha-Interferon and lamivudine combination therapy had a more beneficial effect than alpha-interferon monotherapy in normalization of ALT and clearance of HBV-DNA; however, the complete response rate at 6 months after the end of the therapy was not statistically significantly different between both groups.

Antiviral Agents↗

Interferon-alpha-2b + ribavirin for the treatment of chronic hepatitis C in non-responders to interferon-alpha-monotherapy.

UNLABELLED: The efficacy of a therapy with interferon-alpha-2b and ribavirin in patients with hepatitis C not responding to the initial treatment remains controversial. Objective of the present study was to determine the efficacy of a combination therapy with 3 MU interferon-alpha thrice weekly and 1,000-1,200 mg ribavirin daily for six months in an open label trial. METHODS: 44 consecutive patients (genotype 1: 79.5%) who had been previously treated with a minimum dose of 3 MU interferon-alpha thrice weekly for at least three months were monitored. Sustained response was defined as virological response with clearance of HCV-RNA after a follow-up period of six months after the end of therapy. RESULTS: A significant decrease of the mean levels of AST (34.3 +/- 27.6 vs. 16.4 +/- 13.5 U/L) and ALT (59.6 +/- 48.8 vs. 23.2 +/- 20.7 U/L) was observed. In 15/44 patients (34.1%) a virological end-of-treatment response was evident. 8/44 patients (18.2%) achieved a sustained response. In 33.3% of the previous non-responders biochemical response with normal aminotransferases, but no virological response was evident. A significant decrease of the mean hemoglobin level was observed during therapy (12.0 +/- 1.7 vs. 14.6 +/- 1.0 g/dl; p < 0.005), which returned to the pretreatment values after the end of treatment (14.4 +/- 1.6 g/dl; n.s.). In ten patients (22.7%) decrease of hemoglobin levels < 10 g/dl led to a dose reduction of ribavirin. CONCLUSION: This study--in agreement to recently published data--provides evidence for the efficacy of the combination therapy with interferon-alpha-2b and ribavirin in a relevant subset of non-responders to interferon-alpha. Therapeutic nihilism should be reevaluated in non-responders to interferon-alpha.

Adult↗

Treatment with interferons (including pegylated interferons) in patients with hepatitis B.

Studies of 4 to 6 months of treatment with interferon for hepatitis B e antigen (HBeAg)-positive chronic hepatitis B virus (HBV) infection have shown clearance of HBeAg to be higher in treated patients than it is in controls by approximately 25%. These results are considerably better than those with antiviral agents. Therefore, the recent European Association for the Study of the Liver (EASL) Consensus Committee recommended the use of interferon alpha for this condition. Treatment with pegylated interferons in several trials has shown better results still. Lamivudine in combination with interferon, however, did not improve the results at 6 months after the end of therapy. In HBeAg-negative chronic HBV infection, pegylated interferon alpha is superior to lamivudine, and, again, combination with lamivudine does not improve the results. Side effects in all studies have been tolerable. Thus, these observations in chronic HBV infection, whether HBeAg-positive or HBeAg-negative, suggest an important, even primary, role for pegylated interferon therapy.

Adenine↗

Nephrectomy followed by interferon alfa-2b compared with interferon alfa-2b alone for metastatic renal-cell cancer.

BACKGROUND: The value of nephrectomy in metastatic renal-cell cancer has long been debated. Several nonrandomized studies suggest a higher rate of response to systemic therapy and longer survival in patients who have undergone nephrectomy. METHODS: We randomly assigned patients with metastatic renal-cell cancer who were acceptable candidates for nephrectomy to undergo radical nephrectomy followed by therapy with interferon alfa-2b or to receive interferon alfa-2b therapy alone. The primary end point was survival, and the secondary end point was a response of the tumor to treatment. RESULTS: The median survival of 120 eligible patients assigned to surgery followed by interferon was 11.1 months, and among the 121 eligible patients assigned to interferon alone it was 8.1 months (P=0.05). The difference in median survival between the two groups was independent of performance status, metastatic site, and the presence or absence of a measurable metastatic lesion. CONCLUSIONS: Nephrectomy followed by interferon therapy results in longer survival among patients with metastatic renal-cell cancer than does interferon therapy alone.

Actuarial Analysis↗

Population pharmacokinetic analysis of pegylated interferon alfa-2b and interferon alfa-2b in patients with chronic hepatitis C.

BACKGROUND: This study quantified pharmacokinetic changes in pegylated and nonpegylated interferon alfa-2b during 48 weeks of treatment and the influences of covariates on the basis of sparsely sampled serum concentrations and activity values. Possible relationships between pharmacokinetic and pharmacodynamic variables were investigated. METHODS: Patients with chronic hepatitis C were enrolled in a clinical trial that compared the efficacy of pegylated interferon alfa-2b with interferon alfa-2b. Single blood samples were obtained from each patient at weeks 4, 12, 24, 36, and 48. Three pharmacostatistical models were developed for 2 immunoassays and 1 bioassay. RESULTS: Apparent clearance values of pegylated interferon alfa-2b and interferon alfa-2b at the end of treatment declined 33.7% and 80.0%, respectively, from their week 4 values. Bioactivity increased 41% to 58% at week 48 for different treatment groups. Changes were greatest in the first weeks of administration and diminished during the subsequent months. Body weight had a modest positive effect on clearance values and activity. Within each dose level, no significant associations were observed between pharmacokinetic variables and any pharmacodynamic variables (hepatitis C virus--RNA responses or changes in neutrophils and platelets). CONCLUSIONS: This analysis confirms earlier observations of progressive pharmacokinetic changes in the patients with hepatitis C during 48 weeks of treatment. The absence of a relationship between toxicity or efficacy variables and interferon concentration or activity (within a dose level) suggests that clinical management of patients (eg, for efficacy or to manage toxicity) should be based on clinically derived dosing guidelines rather than on serum concentration or activity criteria.

Adolescent↗

Interferon induction by viruses. IX. Antagonistic activities of virus particles modulated interferon production.

Cells generally responded to viral inducers of interferon (IFN) by generating a dose (multiplicity of infection)-response (interferon-yield) curve which showed a good fit to a model in which the fraction of interferon-yielders corresponded to the fraction of cells infected with one or more particles. These were defined as interferon-inducing particles (IFPs). The IFN-producing capacity of cells infected with these particles was modulated upon coinfection with a second type of virus particle, those with the capacity to suppress IFN production. These were termed interferon induction-suppressing particles (ISPs). In cells coinfected with IFP and ISP the latter were dominant phenotypically. In some systems ISP activity was expressed by IFP when the latter were present at two or more particles per cell. The existence of virus particles with antagonistic activities for interferon induction provides a mechanism for regulating the production of IFN and hence the potential outcome of a virus infection.

Animals↗

Epstein-Barr virus and Herpesvirus saimiri: sensitivity to interferons and interferon inducers.

The in vitro sensitivity of oncogenic herpesviruses, Epstein-Barr virus (EBV), and Herpesvirus saimiri (HVS) to human interferon produced by normal human leukocytes (Le), lymphoblastoid cell lines (LYI), and diploid fibroblasts (Fi) was studied. Four virus strains were used: HVS S295C, the highly oncogenic HVS S396-O, the transforming B95-8 strain of EBV, and the nontransforming P3HR1 strain of EBV. All interferons were active when applied to the cells after absorption of HVS and P3HR1-EBV, although different amounts were required to achieve 50% inhibition of HVS-induced cytopathic effect or EBV-induced early antigen (EA) expression. Transformation of human umbilical cord blood lymphocytes (HCBL) by the B95-8 strain of EBV was prevented only by Le and LYI. In these experiments, the most effective inhibitor of the oncogenic herpesviruses was Le, and the least effective was Fi. The effect of polynucleotides poly(I).poly(C) and the complex of poly(I).poly(C) with poly-L-lysine and carboxymethylcellulose on HVS and EBV was also studied. Their inhibitory action was proportionate to the ability of herpesvirus-infected cells to produce interferon. Thus owl monkey kidney cells, which produce relatively high levels of interferon, required nanogram quantities of polynucleotides to become resistant to HVS. Transformation of HCBL by B95-8-EBV was also prevented by poly(I).poly(C). In Raji cells superinfected with P3HR1-EBV, polynucleotides failed to stimulate interferon, and higher EBV-induced EA expression was observed. The percentage of P3HR1 and Raji cells spontaneously expressing EBV-associated antigens remained unchanged after exposure to either interferon or polynucleotides.

Animals↗

The reaction of the anti-interferon-alpha monoclonal antibody, NK2, with different interferons.

Analysis of the neutralization of human interferon-alpha by the monoclonal antibody NK2 showed, by three different methods, that the avidity constant was about 10(10)M-1. A small decrease in the avidity constant (and in the antibody titre) with increasing interferon concentrations was observed, suggesting that the antibody-interferon complex had a little biological activity. The antibody neutralizes the interferon by preventing the binding of interferon to susceptible cells. It does not react with human-gamma, mouse-alpha, monkey, bovine or rabbit interferons.

Antibodies, Monoclonal↗

Short- and long-term effects of therapy with interferon-alpha and pegylated interferon-alpha/ribavirin on platelet plug formation and von Willebrand factor release in patients with chronic hepatitis C.

BACKGROUND: A pegylated interferon-alpha-induced decrease in platelet counts may become a limiting factor for continuation of therapy. AIM: To evaluate the effect of pegylated interferon-alpha administration on platelet plug formation and von Willebrand factor antigen release in patients with chronic hepatitis C. METHODS: Thirty patients with chronic hepatitis C (genotype 1; fibrosis 1-3: n = 16, cirrhosis: n = 14) received a single dose of 9 MU interferon-alpha2a, followed by weekly administration of 180 mug of pegylated interferon-alpha2a/ribavirin for 48 weeks. Platelet counts, platelet function (collagen-epinephrine-induced closure time) and von Willebrand factor antigen were measured. RESULTS: Platelet counts and collagen-epinephrine-induced closure time decreased by 13% and 16%, respectively, 24 h after the first dose of interferon-alpha2a, and von Willebrand factor antigen levels increased by 31% (P < 0.01) compared with baseline. During a 48-week observation period, platelet counts decreased by a maximum of 33% (P < 0.001), von Willebrand factor antigen levels increased by 69% (P < 0.001) whereas collagen-epinephrine-induced closure time did not change. In noncirrhotic patients, the increase of von Willebrand factor antigen levels was maintained throughout therapy without a change in collagen-epinephrine-induced closure time. In contrast, in cirrhotics, von Willebrand factor antigen levels did not increase, while collagen-epinephrine-induced closure time was prolonged. CONCLUSION: Single-dose interferon-alpha decreases platelet counts but improves platelet function, possibly by the release of von Willebrand factor antigen. Accordingly, long-term antiviral treatment had no effect on collagen-epinephrine-induced closure time, despite the decrease in platelet count in noncirrhotic patients. Such a compensation of decreased platelet counts by increased von Willebrand factor antigen level did not occur in cirrhotics.

Adult↗

Randomised, double blind, placebo controlled trial of interferon, ribavirin, and amantadine versus interferon, ribavirin, and placebo in treatment naïve patients with chronic hepatitis C.

BACKGROUND AND AIM: In this study, we compared the efficacy of triple therapy (interferon alfa, ribavirin, and amantadine) with standard therapy (interferon alfa and ribavirin) in treatment naïve patients with chronic hepatitis C virus (HCV). METHODS: In this prospective, randomised, double blind, placebo controlled, multicentre study, 85 patients (amantadine group) received a three drug regimen of interferon alfa-2b 3 million units three times per week, ribavirin 1000-1200 mg daily in divided doses, and amantadine 100 mg twice daily, and 86 patients (placebo group) received interferon alfa-2b, ribavirin, and identical placebo. Treatment was discontinued at 24 weeks if patients had detectable HCV RNA by polymerase chain reaction (PCR). All patients were followed for 24 weeks after completion of treatment. The primary end point was undetectable HCV-RNA by PCR at 24 weeks (sustained viral clearance) after completion of treatment. RESULTS: At the end of treatment, HCV RNA clearance was seen in 32.9% of the amantadine group and 38.4% of the placebo group (p=0.3). Sustained virological response was seen in 24.7% of the amantadine group and in 27.9% of the placebo group by intention to treat analysis; response rate was 30.4% and 34.8%, respectively, in those who completed 24 weeks of treatment. Poor response was seen in both groups among cirrhotics, African-Americans, genotype 1, and those with a higher viral load. By multivariate analysis, genotype 1, high viral load, and low serum albumin were the only predictors of poor response. Addition of amantadine to the standard regimen did not result in any unexpected side effects. CONCLUSION: Response to triple therapy of interferon alfa, ribavirin, and amantadine was similar to standard therapy of interferon alfa and ribavirin. Our results suggest that amantadine has no role in the management of HCV.

Adult↗

Systemic therapy of advanced metastatic malignant melanoma with a combination of fibroblast interferon-beta and recombinant interferon-gamma.

Eighteen patients with advanced metastatic malignant melanoma (stage IVUICC 1987) were entered into a prospective trial with a combination of systemic fibroblast interferon-beta and recombinant interferon-gamma. Treatment was performed over a 6-week period with 3 x 5 x 10(6) U i.v. interferon-beta and 5 X 100 micrograms s.c. interferon-gamma every week. Under this therapy 16 patients showed a progressive disease, and 2 patients had a stable disease. The median time of survival was 7.5 months. Successive immunological examinations showed no significant immunomodulating effect after the 6 weeks of interferon treatment. We conclude that the combination of interferon-beta and -gamma is insufficient in the treatment of advanced metastatic malignant melanoma when administered by this dose, route and schedule.

Adult↗

Interferon gamma producing blood lymphocytes are decreased by interferon beta therapy in patients with multiple sclerosis.

OBJECTIVE: We studied the individual course of interferon gamma producing blood lymphocyte count (IFGC) of 15 multiple sclerosis patients started on 8 MIU beta interferon administered subcutaneously each other day. METHODS: Mononuclear blood cells were prepared before treatment and on day 3, 9, 15, as well as after month 1, 2, 3 and 4 of therapy. After stimulation intracellular interferon gamma was detected with monoclonal fluorescent antibodies and measured by flow cytometry. IFGC is given as percentage of all gated lymphocytes. RESULTS: forty-eight hours after first interferon beta application the mean IFGC dropped significantly from 11.37 to 7.09 (P < 0.05) and to 4.22 within 4 months. Whereas the majority of patients showed a decrease of IFGC from the beginning of therapy, in three of the 15 patients a transient increase of IFGC was seen suggesting a different response to immunomodulatory therapy. CONCLUSIONS: Interferon gamma producing lymphocyte count might be a useful tool to determine the biological effect of interferon beta therapy in multiple sclerosis patients.

Adjuvants, Immunologic↗