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Natural resistance in mice against Friend leukemia cells. II. Studies with in vivo passaged interferon-sensitive and interferon-resistant cell clones.

Experiments were designed to test the presence of antitumor natural resistance (NR) in DBA/2 mice against highly oncogenic in vivo passaged histocompatible Friend leukemia cells (FLC-V). NR was measured in vivo as rapid clearance of radiolabeled cells from different organs or as growth inhibition in lethally irradiated mice. Interferon-sensitive (745) or interferon-resistant (3C18) lines were used. Organ clearance studies showed that young recipients eliminate cells more rapidly than old mice. Moreover, depressive (e.g., cyclophosphamide or carrageenen) or enhancing (e.g., poly (I:C) or Friend leukemia virus infection) agents of NR function modulate accordingly leukemia cell clearance. Similar results were obtained testing tumor growth in lethally irradiated hosts, although modulating agents were substantially less effective in this system. Both FLC-745-V and FLC-3C18-V lines were equally susceptible to NR. Therefore, these data provide further support to the hypothesis that exogenous IFN capable of suppressing the growth of both lines could act via enhancement of the NR function.

Animals↗

Hydrophobic cluster analysis reveals duplication in the external structure of human alpha-interferon receptor and homology with gamma-interferon receptor external domain.

Evidence is presented, based on sequence comparison according to Hydrophobic Cluster Analysis, of a structural and evolutionary relationship between the human alpha/beta-interferon receptor and the human and mouse gamma-interferon receptor. These results predict that the human alpha/beta-interferon receptor extracellular part is organised in two homologous subdomains connected by a proline linker. They also predict that both subdomains present some homologies to the external domain of mouse and human gamma interferon receptor.

Amino Acid Sequence↗

Interferons as gene activators: a cluster of six interferon-activatable genes is linked to the erythroid alpha-spectrin locus on murine chromosome 1.

Several interferon-activatable murine genes were mapped to murine chromosomes by hybridizing cDNA probes to Southern blots of genomic DNA samples from a panel of mouse-hamster somatic cell hybrid lines. The 12 gene is located on chromosome 12 and it specifies a 3.6-kb mRNA. The 204 gene (specifying a 2.5-kb mRNA), and three genes of the 203 gene family (hybridizing to five mRNAs of sizes between 2 and 4.5 kb), together with the 202 gene (specifying a 2-kb mRNA) are located on murine chromosome 1. By restriction fragment length polymorphism analysis of DNA samples prepared from a panel of recombinant inbred mouse lines (C57BL/6J D DBA/2J) and from 85 [C3H/HeJ-gld/gld x Mus spretus) F1 X C3H/HeJ-gld/gld] backcross mice we established a close linkage of the 202, 203, and 204 genes to the erythroid alpha-spectrin gene (Spna-1) on distal murine chromosome 1. Cosmids containing the 202, 203, and 204 genes were isolated from a library derived from AKR mouse DNA. Southern blot analysis of such cosmids revealed: (a) hybridization of a partial 203 cDNA to three genes of the 203 gene family; (b) cross-hybridization of the 202 and 204 genes with one another and with a third gene (designated as 201 gene), and (c) a close linkage of genes of the 203 family with the 201, 202, and 204 genes. These results indicate the existence of a cluster of at least six closely linked, interferon-activatable genes on distal murine chromosome 1 in the vicinity of the Spna-1 locus and also of the Minor lymphocyte stimulating locus (Mlsa).

Animals↗

Effects of interferon and retinoic acid on the growth and differentiation of clonogenic leukemic cells from acute myelogenous leukemia patients treated with recombinant leukocyte-alpha A interferon.

Studies with human myeloid leukemia cell lines indicate that combined interferon (INF) and retinoic acid (RA) have greater effects in inhibiting cell growth and in inducing terminal differentiation than either agent alone. Consequently, we studied the effects of these agents, singly and in combination, on fresh leukemic blast cells obtained from 13 acute myelogenous leukemia (AML) patients, most of whom were subsequently treated with recombinant leukocyte-alpha A interferon (rINF-alpha A). The in-vitro response to rINF-alpha A and RA was assessed in an established myeloid leukemic blast cell clonogenic assay containing conditioned medium from phytohemagglutinin-stimulated lymphocytes. Strong inhibition of colony cell growth (greater than or equal to 50%) was observed in 4/10 cases treated with rINF-alpha A alone, but only at high concentration (greater than or equal to 2500 U/ml) and in 4/10 cases treated with RA alone (5 X 10(-8) M or 5 X 10(-7) M). Combined rINF-alpha A and RA augmented the inhibition of primary or secondary colony cell growth in 5/8 evaluable cases. Stimulation of leukemic cell differentiation was observed in 1/8 cases by rINF-alpha A alone and in 4/7 cases by RA alone. Combined rINF-alpha A and RA enhanced cell differentiation in 4/7 cases. In addition, increased inhibition of clonal cell growth and/or differentiation by RA alone was observed in 2/5 cases following in-vivo rINF-alpha A treatment. These results suggest that treatment with combined rINF-alpha A and RA may be rewarding in some cases of AML.

Cell Differentiation↗

Interferon-beta induced remission in a hairy cell leukemia patient resistant to interferon-alpha.

Two patients with advanced hairy cell leukemia and pancytopenia responded successfully to intramuscular injections of recombinant interferon-beta, with normalisation of blood counts. One of the patients had developed resistance to interferon-alpha. The in-vivo response was predicted by in-vitro studies showing a beneficial effect of IFN-beta on erythropoiesis in cell cultures derived from these patients.

Bone Marrow↗

Age-related increase of porcine natural interferon alpha producing cell frequency and of interferon yield per cell.

Porcine blood mononuclear cells (PBMC) were shown to secrete interferon alpha (IFN-alpha) after induction by a coronavirus, the transmissible gastroenteritis virus (TGEV). IFN-alpha producing cells, referred to as natural interferon alpha producing (NIP) cells, were detected by an ELISPOT assay using anti-porcine IFN-alpha monoclonal antibodies. The frequency of NIP cells among blood cells is low, at most 40-110 per 10(5) PBMC and each NIP cell was found to produce several units of IFN. We have shown that NIP cell frequency and IFN yield per cell gradually increased with the age of the donor animals, from the neonatal period to the adult age, with a significant increase around puberty. Our present results also indicate that NIP cells may be influenced by physiological and genetic factors; thus (1) NIP cell frequency and IFN yield per cell were decreased during lactation; (2) Chinese (Meishan) pigs were found to have higher NIP cell frequency and IFN yield per cell than European (Large White) animals.

Aging↗

Blocking of interferon synthesis in murine macrophages by pretreatment with interferon.

The influence of pretreatment with interferon (IFN) on subsequent IFN synthesis was investigated in macrophage cultures of DBA/2 and C57BL/6 mice. The doses of IFN alpha/beta for pretreatment ranged from 10,000 U/ml to 100 U/ml and the incubation time was between 18 and 2 h. No blocking effect was observed for chemical induction with poly I:poly C or CMA. However, for viral infection with NDV, blocking was observed. This inhibition of IFN synthesis was dependent on the dose and time of IFN pretreatment and of the titer of the inducing virus. Similarly in mouse fibroblast cultures no blocking activity was observed for induction with poly I:poly C/DEAE-dextran. Again, with NDV as inducer, pretreatment with IFN resulted in inhibition of interferon synthesis. Thus, our data show that blocking occurs only with a viral inducer and suggest that it is caused by an antiviral effect.

Animals↗

Anti-interferon antibody increases rhinovirus isolation rates from nasal wash specimens containing interferon-alpha 2.

Isolation of rhinoviruses from nasal secretions may be delayed or prevented by exogenously applied interferon which is carried over into nasal wash specimens. In studies of interferon-alpha 2 treated volunteers with experimental rhinovirus infection, we determined that incorporation of antiinterferon antibody into collection broth significantly increased isolation rates (84% increase) and the proportion of monolayers positive for CPE (155% increase), as compared to plain collection broth.

Antibodies↗

Interferon antibodies in patients with chronic HBV infection treated with recombinant interferon.

In different trials, a total of 46 adults and 12 children suffering from chronic hepatitis B virus (HBV) and who were HBV-DNA- and HBeAg-positive were treated with recombinant interferon-alpha (rIFN alpha)-2A. The interferon was administered intramuscularly in different doses ranging from 1.5 MU to 20 MU/m2 of body surface, two or three times weekly during 4-6 months. Specific detection of anti-IFN antibodies by enzymoimmunoassay (EIA), radioimmunoassay (RIA) and biological assays during treatment and follow-up periods were performed. None of the children developed anti-IFN antibodies. During therapy, 12 adult patients (26%) were found to have anti-IFN antibodies. A total of five patients became HBV-DNA-negative during therapy, but in three cases a reactivation of viral replication occurred subsequently. In these three patients, the appearance of anti-IFN antibodies occurred prior to or at the same time as HBV-DNA loss. The other seven patients did not respond to therapy. In conclusion, the development of anti-IFN antibodies during rIFN alpha treatment of chronic hepatitis B may modify the response to therapy, especially if they appear before HBV-DNA negativization.

Adolescent↗

Treatment of malignant ascites due to recurrent/refractory ovarian cancer: the use of interferon-alpha or interferon-alpha plus chemotherapy in vivo and in vitro.

Intraperitoneal treatment with interferon (IFN) for malignant ascites due to advanced ovarian carcinoma refractory to chemotherapy gave an objective response rate of 36% (7/19 patients treated). In vitro studies demonstrated that cytotoxicity of peripheral blood monocytes/macrophages was stimulated by IFN. However, peritoneal exudate cells obtained after intraperitoneal treatment with interferon were not stimulated to kill autologous tumour cells. Clinical response was therefore most probably due to a direct inhibitory effect of IFN on growth of malignant cells rather than due to an immune modulatory effect. Using a newly established ovarian cancer cell line (UWOV1), synergy between the growth inhibitory/antitumour effects of IFN and cisplatin was demonstrated at clinically achievable concentrations of each agent. IFN plus cisplatin proved to be more effective than intraperitoneal cisplatin alone in control of peritoneal carcinomatosis. The response rate was 5/7 (77%) for combined modality therapy vs. 2/9 (22%) for intraperitoneal chemotherapy alone. Both in vitro and in vivo studies suggest a role for interperitoneal therapy for control of refractory ascites in ovarian cancer.

Adult↗

Multiple stat complexes interact at the interferon regulatory factor-1 interferon-gamma activation sequence in prolactin-stimulated Nb2 T cells.

Interferon regulatory factor-1 (IRF-1) is a major immediate early gene induced by prolactin (PRL) in a biphasic, cell cycle-dependent manner in Nb2 T cells. This biphasic expression (30 min and 10 h) is mediated in part by an interferon-gamma activation sequence (GAS) in the IRF-1 promoter which binds factors belonging to the Signal Transducers and Activators of Transcription (Stat) family. By electrophoretic mobility shift assays (EMSA), Stat1 alpha was found to be the major and Stat5a a minor component of the 30 min complex. At 10 h, Stat-like factors were again found at the IRF-1 GAS. Western blot analyses show that Stat5a was rapidly induced by PRL to enter the nucleus, but unexpectedly, Stat1 alpha and the alternatively-spliced Stat1 beta were already present in the uninduced nucleus. Further, Stat1 alpha but not Stat1 beta is preferentially tyrosine phosphorylated in response to PRL stimulation. Our studies suggest that multiple Stat complexes may contribute to the biphasic transcription of the IRF-1 gene in PRL-stimulated T cells.

DNA-Binding Proteins↗

Effect of an interferon inhibitor on the antiproliferative signal of interferon-alpha.

We have described a nonantibody type inhibitor of interferons (IFN) in the blood of patients with AIDS, advanced neoplastic disorders, and lupus erythematosus in earlier reports (1,2). In the present study we show that the semipurified inhibitor blocks the antiproliferative signal of IFN-alpha in Daudi cells and the membrane potential shifting ability of IFN-alpha is modulated by the interferon inhibitor preparation (IFI).

Cell Division↗

Comparative pathology of recombinant murine interferon-gamma in mice and recombinant human interferon-gamma in cynomolgus monkeys.

Interferon-gamma is a highly species-specific cytokine and has the most restricted host range of activity of the interferons. Recombinant human IFN-gamma was one of the first species-specific recombinant proteins to be thoroughly assessed in conventional safety models used for xenobiotics. Acute single-dose intravenous toxicity studies with rHuIFN-gamma were performed in rats, marmosets, and squirrel monkeys with no indications of toxicity. A complete series of subchronic toxicity studies and segment I and II reproductive studies in the rat revealed no evidence of toxicity at any of the doses tested. These results suggested that studies conducted in pharmacologically nonresponsive species may not be predictive of clinical toxicity. Human IFN-gamma is active on nonhuman primate cells, though not at the same level as on human cells. Multidose studies in cynomolgus monkeys with rHuIFN-gamma for 28 or 90 days were predictive of many of the dose-limiting clinical toxicities. Qualitative similarity was observed between toxicity studies employing rHuIFN-gamma in the cynomolgus monkey and rMuIFN-gamma in the mouse. The adverse effects seen in toxicity studies with cytokines and growth factors are often exaggerated pharmacological effects of the molecules, and therefore can only be studied in a responsive species. In situations in which a high degree of species specificity is encountered, studies employing a recombinant protein in a homologous species may provide a useful test system for preclinical safety assessment.

Abnormalities, Drug-Induced↗

Antigen presenting cell-independent cytokine and spontaneous in vitro IgE production in patients with atopic dermatitis: increased interferon-gamma production and lack of effects of in vivo low-dose interferon-gamma treatment.

Atopic dermatitis is characterized by elevated serum IgE concentrations and dysregulation of T-lymphocyte function. To examine the pattern of cytokine production associated with elevated IgE levels, phorbol ester plus ionomycin-stimulated production of interleukin (IL)-4, IL-5, and interferon-gamma (IFN-gamma) by blood mononuclear cells from 16 patients with atopic dermatitis was compared with that of 18 healthy subjects. Spontaneous in vitro IgE production was also studied longitudinally in patients receiving placebo or daily treatment with 0.05 mg/m2 IFN-gamma. Spontaneous in vitro IgE production and mitogen-driven IL-4 and IFN-gamma synthesis did not differ when patients were receiving interferon treatment compared with no treatment. Furthermore, ionomycin plus phorbol ester-stimulated mononuclear cells from patients with atopic dermatitis produced less IL-4 and more IFN-gamma than did cells from healthy subjects. IL-5 production by cells from patients with atopic dermatitis did not differ from that of cells from healthy subjects. The ratio of IL-4 to IFN-gamma produced in vitro was significantly lower (p = 0.04) in the cells of patients with atopic dermatitis (0.9) as compared with those of healthy subjects (2.7). The findings suggest that when circulating T cells are stimulated under antigen presenting cell-independent conditions, atopic dermatitis is not characterized by the shift in the reciprocal relationship between IL-4 and IFN-gamma production, which has been postulated to explain the pathogenesis of IgE elevation and the therapeutic action of IFN-gamma in patients with atopic dermatitis.

Adult↗

Increased levels of antibodies against interferon-alpha in HIV-1 positive individuals may be explained by a common immunological epitope on the human interferon-alpha and HIV-1 gp41.

Based on the similar effects of HIV-1 gp41 and human type I interferons on inhibition of lymphocyte proliferation and modulation of MHC class I and II molecule expression, we compared amino acid sequences of human interferons with HIV-1 gp41 and found sequence-similarity existing between gp41 and IFN-alpha. Anti-gp41-antibodies affinity-purified from sera of HIV-1-infected individuals (stage A) using rsgp41-Sepharose column could recognize human IFN-alpha in ELISA, but no antibody against IFN-alpha was detected if immunoglobulins were prepared in the same way from pooled HIV-negative serum. Besides, a sheep polyclonal anti-human IFN-alpha antibody bound weakly to recombinant soluble gp41 (rsgp41) of HIV-1IIIB. These results indicate that gp41 may share an immunological epitope with IFN-alpha. We examined 40 sera from healthy and asymptomatic HIV-1-infected individuals and AIDS-patients for IFN-alpha antibody levels by ELISA. The levels of anti-IFN-alpha antibody in sera from asymptomatic HIV-infected individuals (stage A, n = 6) was increased by about 150% in comparison with HIV-negative, but the antibody levels were obviously reduced in the case of symptomatic HIV-infected individuals (stage B, n = 7) and AIDS-patients (stage C, n = 7) in comparison with asymptomatic HIV-infected individuals (stage A). We suppose that the increased IFN-alpha-antibody level in HIV-1-infected individuals (stage A) may be due to this common immunological epitope and cross-reaction of antibodies to HIV-1 gp41 with IFN-alpha.

Acquired Immunodeficiency Syndrome↗

Long-term response to interferon alpha is unrelated to "interferon sensitivity determining region" variability in patients with chronic hepatitis C virus-1b infection.

BACKGROUND/AIMS: Contradictory data have been reported about the predictive value of the variability in interferon sensitivity determining region (ISDR) of hepatitis C virus (HCV) genotype-1b on response to interferon-alpha (IFN-alpha) therapy. The aim of this study was to examine this issue in a series of patients with long-term response to IFN treatment. METHODS: We retrospectively analyzed 24 patients with chronic HCV genotype-1b infection treated with IFN-alpha (total dose median 677, range 216-1350 MU) selected in 6 Italian Liver Units. These patients were defined as true long-term responders (LTR) since they showed persisting biochemical and virological responses to IFN treatment (mean follow-up 38 months). HCV genomes from pretreatment serum samples were amplified and directly sequenced. The ISDR amino-acid sequences obtained were aligned and compared with the published sequence of HCV-J. RESULTS: Amino-acid substitutions were found in 23 of the 24 patients, and 22 of them showed an H to R amino-acid change at codon 2218. Fourteen patients showed only one mutation (at codon 2218), two had 2, five had 3, one had 4 and one had 5 mutations. When we compared the ISDR sequences from the 24 LTR with those of non-responders (NR), we found no significant correlation between the number of mutations and the response to therapy. CONCLUSIONS: Our results demonstrate that the persisting efficacy of IFN treatment in patients with chronic HCV is not related to the number of ISDR amino acid substitutions of the infecting viruses. Further studies are needed to verify whether other NS5A sequences outside the ISDR might be involved in the mechanisms of IFN resistance.

Adult↗

Efficacy of a short-term ribavirin plus interferon alpha combination therapy followed by interferon alpha alone in previously untreated patients with chronic hepatitis C: a randomized multicenter trial.

BACKGROUND: Combination therapy with interferon alpha (IFNalpha) plus ribavirin has been shown to improve the sustained response rate in patients with chronic hepatitis C but there is little information regarding the lengths of time for this therapeutic regimen. In this study we therefore tried to evaluate whether the analysis of different virological parameters could provide new clues with respect to the early determination of the efficacy of this form of combination therapy. Furthermore, we also examined whether short-term induction combination therapy followed by IFNalpha alone is more effective than monotherapy in mounting an initial as well as a sustained virological response. METHODS: 185 patients with histologically proven chronic hepatitis C (mean age 42 years (range 19-65 years); 110 males, 75 females) were enrolled in the study. The patients were randomly assigned to receive, over the first 12 weeks, either interferon alpha 2a 6 million units (MU) three times weekly plus ribavirin 14 mg/kg per day (n=93) or the same dose of IFNalpha alone (n=92). Patients with a virological response (serum HCV RNA undetectable) after 12 weeks were subsequently treated with 3 MU IFNalpha alone thrice weekly for a further 40 weeks. Otherwise, treatment was discontinued. After the end of treatment, patients were followed up for 24 weeks. RESULTS: Patient characteristics at baseline were not significantly different in the two treatment groups. An initial virological response at week 12 was seen in 61 (66%) patients receiving IFNalpha plus ribavirin and in 44 (48%) being treated with IFNalpha alone (p=0.015) and this improvement in the response rate was mainly restricted to HCV genotype 1-infected patients (58% vs. 38%). In contrast, end-of-treatment (week 52) and sustained virological response rates were similar in both groups (37% vs. 29% and 26% vs. 17% [p=0.1], respectively). Interestingly, patients with HCV genotype 3, however, clearly benefited from short-term combination therapy. Thus, sustained virological response rates in these patients significantly increased from 25% (IFNalpha monotherapy) to 59% (combination therapy) (p=0.05). CONCLUSIONS: Short-term combined therapy for 12 weeks is more effective than the monotherapy with respect to the induction of an initial virological response but this effect applies only to genotype 1-infected patients. However, there is no significant difference between both therapeutic schedules with regard to the induction of sustained response. Although HCV genotype 3-infected patients seem to benefit from this short-term combined therapy, prolonged combined therapy may be necessary in HCV genotype 1-infected patients.

Adult↗

Interferon-neutralizing antibodies in a patient treated with human fibroblast interferon.

During recent years clinical trials have shown that human leukocyte interferon (HuIFN-alpha) may be useful in the treatment of cancer, but very little has been done concerning the possible use of human fibroblast interferon (HuIFN-beta). Treuner et al. recently reported the successful treatment of a nasopharyngeal carcinoma with HuIFN-beta: in the course of IFN-therapy a HuIFN-beta neutralizing activity appeared in the serum of this patient. We report here that such activity is due to IgG antibodies--this study is the first to present evidence for antigenicity of IFN in a homologous system.

Antibody Formation↗