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Biomedical subjects

F Dianzani

Publications and source records attributed to F Dianzani.

At least 19 recordsLinked to original sources
PubMed1992

In vitro selection of human immunodeficiency virus type 1 resistant to 3'-azido-3'-deoxythymidine.

3'-Azido-3'-deoxythymidine (AZT)-resistant human immunodeficiency virus type 1 (HIV-1) was obtained by growing HTLV-IIIB in C8166 cell cultures in the presence of inhibitory concentrations of AZT. The AZT-resistant HIV-1 was capable of replicating, as measured by infectious virus yield, and inducing cytopathic effect in the presence of AZT concentrations able to completely suppress the replication of parental HTLV-IIIB. Cloning of the AZT-resistant HIV-1 revealed that a number of different variants of HIV-1 with various degrees of sensitivity to AZT emerged during propagation of HTLV-IIIB in C8166 cells in the presence of the drug. PCR experiments performed on DNA extracted from C8166 cells infected with a resistant strain revealed that viral DNA was produced in the presence of inhibitory concentrations of AZT, while viral DNA in C8166 cells infected with the parental virus was drastically inhibited. Reverse transcriptase isolated from the AZT-resistant HIV-1 variant failed to show resistance to AZT 5'-triphosphate.

Antiviral Agents↗
PubMed1992

Resistance of HIV-1 to AZT might also involve the cellular expression of multidrug resistance P-glycoprotein.

Resistance of tumor cells to the antigrowth activity of several cytotoxic compounds has been associated with the expression of the so-called multidrug resistance protein or P-glycoprotein. This article addresses the question whether the expression of such protein could also affect the sensitivity of HIV to AZT. Our data indicate that this possibility does exist. In fact, multidrug-resistant CEM VBL100 cells, which express high levels of P-glycoprotein, are less sensitive to both the antiproliferative activity and the antiviral action of AZT. Additionally, our data suggest that this phenomenon is specifically mediated by P-glycoprotein since trifluoroperazine, which is known to circumvent multidrug resistance due to the action on P-glycoprotein, increases the intracellular accumulation of AZT and affects the sensitivity of HIV to AZT. Although the biological and clinical significance of these observations has still to be established, this study suggests that cellular factors, other than virus itself, should be taken into account to address the phenomenon of drug resistance of HIV.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Recombinant glycoprotein 120 of human immunodeficiency virus is a potent interferon inducer.

Cells infected with human immunodeficiency virus (HIV) induce antiviral activity in peripheral blood mononuclear cells (PBMC) from healthy donors. This activity is neutralized by anti-interferon-alpha antibody and partially destroyed at pH 2. Previous studies with enriched cell populations and monoclonal antibodies suggest that B lymphocytes are the main IFN-producing cells, and that both CD4 and HLA class II antigens are essential for IFN induction. Since the initial event of HIV infection of CD4+ cells is the interaction of the virus coat glycoprotein gp120 with CD4 molecule, we investigated whether gp120 is responsible for IFN induction. Using PBMC and recombinant gp120 obtained from a baculovirus expression system, dose-dependent induction of antiviral activity was observed with titers approaching 10(3) IU/ml. This induction was blocked in the presence of antibody to gp120. The antiviral activity was characterized as IFN-alpha by neutralization with IFN alpha-specific antibody. Preincubation of PBMC with anti-CD4 or the presence of soluble CD4 during incubation inhibited IFN induction, indicating that interaction of gp120 with cell-associated CD4 is responsible for this induction. Neither lymphoproliferation nor interleukin-2 (IL-2) production was observed during IFN induction. However, class G immunoglobulin secretion was enhanced by gp120, indicating that B cells are direct or indirect targets of gp120 stimulation in this experimental system. Since gp120 is shed from HIV-infected cells and occurs in the serum of acquired immunodeficiency syndrome (AIDS) patients, our data suggest that this glycoprotein is responsible for the induction of endogenous IFN and the polyclonal activation of B cells both of which are observed in AIDS patients.

B-Lymphocytes↗
PubMed1992

Acid lability is not an intrinsic property of interferon-alpha induced by HIV-infected cells.

Human immunodeficiency virus (HIV)-infected cells induce acid-labile interferon-alpha (al-IFN-alpha) in cultures of mononuclear cells from peripheral human blood. We have investigated the physiochemical properties of such preparations to elucidate the reasons for acid-lability of this IFN. Al-IFN-alpha is a mixture of both glycosylated and unglycosylated molecules as shown by separation on Concanavalin-A Sepharose. Acid-lability is associated only with glycosylated molecules. Upon chromatography of the glycosylated fraction on Sepharose coupled to IFN-alpha-specific antibody, the portion of the IFN that is retained and eluted with guanidine-HCl is acid-stable, whereas the excluded antiviral activity is acid-labile, and is partially neutralized by antibodies to either IFN-alpha or IFN-gamma. Also, upon further purification of the unglycosylated fraction on the same antibody column, all antiviral activity remains indistinguishable from conventional IFN-alpha. Reconstitution experiments showed that glycosylated material excluded from the anti-IFN-alpha column potentiates antiviral activity of the IFN that is specifically retained by the column. This potentiation is abolished by acid treatment. Similar results are obtained with al-IFN-alpha from the serum of acquired immunodeficiency syndrome (AIDS) patients, indicating that its acid-lability is also the consequence of an acid-labile component that is capable of enhancing the antiviral activity. The potentiation of antiviral activity obtained by combining recombinant preparations of IFN-alpha and IFN-gamma suggests that the cooperating molecule is IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗
PubMed1992

Decreased interferon response by lymphocytes from children with chronic hepatitis.

Since a decreased interferon response has been linked with certain chronic viral infections, a preliminary study was undertaken to determine whether an altered interferon response may be involved in the pathogenesis of chronic hepatitis, a complication of type B hepatitis. The production of interferon by lymphocytes from patients with chronic hepatitis was compared with the production by lymphocytes from normal subjects. The amount of interferon produced by paramyxovirus-stimulated lymphocytes from 16 patients was substantially smaller than that produced by lymphocytes from 12 healthy donors. The results indicate that decreased production of interferon may be responsible for the chronicity of the disease. However, further studies are necessary to establish causality.

Child↗
PubMed1992

Absence of circulating interferon in patients with inflammatory bowel disease. Suggestion against an autoimmune etiology.

Whether inflammatory bowel diseases (IBD) can be classified as autoimmune disorders is not established. Since circulating acid-labile interferon-alpha (IFN-alpha) is believed to reflect autoimmune reactions, we tested sera from two groups of IBD patients for the presence of circulating IFN. No detectable IFN was found in 51 serum samples of IBD patients. Furthermore, in no serum sample of IBD patients were neutralizing anti-IFN antibodies found. In contrast, acid-labile IFN-alpha was present in sera from 21/52 HIV-infected and from 6/14 systemic lupus erythematosus patients. These observations provide evidence that IBD differs from systemic autoimmune disorders, at least for the presence of circulating IFN.

Autoantibodies↗
PubMed1992

Interferon-alpha (IFN-alpha) production by human intestinal mononuclear cells. Response to virus in control subjects and in Crohn's disease.

The virus induced production of interferon alpha by human intestinal lamina propria mononuclear cells was investigated. Intestinal and autologous peripheral cells from control subjects and patients with Crohn's disease were cultured in vitro with and without stimulation with the Newcastle disease virus. Interferon alpha was measured and characterised in the culture supernatants after 12 hours and the kinetics of production was evaluated over the following four days of culture. No detectable interferon alpha was found in cultures of unstimulated intestinal and autologous peripheral mononuclear cells from controls and Crohn's disease whereas interferon alpha was released in all cultures stimulated with the virus. In all 12 hours experiments in both groups, virus stimulated intestinal mononuclear cells yielded significantly less interferon alpha than the autologous peripheral cells. The kinetics experiments showed that control intestinal mononuclear cells appeared to be poorly responsive to virus stimulation showing a release of interferon alpha significantly lower than that of the autologous peripheral cells. The interferon alpha release at day 4 by control cells (either intestinal or peripheral) did not differ from that measured after the first 12 hours. In contrast, the interferon alpha produced by Crohn's disease cells progressively increased during the culture period and the amount of interferon alpha measured at day 4 was significantly higher than that released at 12 hours. These data suggest that normal human intestinal mononuclear cells are down regulated in their capability of producing interferon alpha and that in Crohn's disease their activation for this function is enhanced. These data also suggest that in Crohn's disease intestinal mononuclear cells exhibit a transient hyporesponsiveness to in vitro stimulation possibly related to massive in vivo exposure to interferon alpha inducers.

Cells, Cultured↗
PubMed1992

[Acquired immunodeficiency virus (HIV-1). Biological aspects and virological diagnosis].

The etiologic agent of the acquired immunodeficiency syndrome is a retrovirus included in the subclass of lentiviruses in view of certain characteristics common to these viruses. Their similarity is mainly represented by the extreme slowness of disease manifestation and by the fact that HIV, like other lentiviruses, spreads within the organism in spite of an immune reaction. The mechanism of replication is not dissimilar to that of other retroviruses except for the expression of a particularly large number of regulating genes the most important of which are called tat, rev, and nef. Further genes with a probable regulating function are nef, vpr, and vpx. In the field of diagnostic virology, together with normal isolation tests, a technique that has become particularly important is PCR (polymerase chain reaction) which allows to obtain a relevant amount of specific viral DNA sequences by the use of a DNA polymerase and specific primers.

AIDS Serodiagnosis↗
PubMed1991

Long-term results of therapy with interferon-alpha for type II essential mixed cryoglobulinemia.

Severe type II essential mixed cryoglobulinemia (EMC) bears a poor prognosis. Treatment with corticosteroids and/or cytotoxic drugs infrequently results in long-term remissions, and is associated with significant toxicity. We conducted a prospective study with interferon (IFN) in 21 patients with severe type II EMC unresponsive to immunosuppressive regimens. They were treated with recombinant IFN-alpha 2a (18 patients) or with natural IFN-beta (three patients), alone, at a dosage of 3 megaunits (MU)/d for 3 months, followed by 3 MU every other day as maintenance. We observed 11 complete remissions, five partial remissions, and five minor responses. Of 16 patients observed for more than 1 year, 11 remained in remission for 14 to 40 months; five of them remained in complete remission for 18 to 40 months after withdrawal of treatment. Four patients discontinued treatment because of side effects. In four patients who relapsed while on maintenance therapy with recombinant IFN-alpha 2a, remission could be reinduced by treatment with natural IFN-alpha. The response rate of 77% achieved in this study prompts the use of IFN-alpha as a first-choice drug for type II EMC.

Adult↗
PubMed1991

Evolving modalities of treatment with interferon alfa-2b for Ph1-positive chronic myelogenous leukaemia.

We have administered interferon alfa-2b, alone or in combination with chemotherapy, to 126 Ph1-positive chronic myelogenous leukaemia patients. Of 71 early chronic phase (CP) patients (less than 12 months from diagnosis), 41 (58%) obtained a complete haematological response (CHR). Daily interferon was more effective than intermittent administration. In previously untreated patients, the response was significantly influenced by risk status at diagnosis. Thirty-four out of 71 (48%) patients improved cytogenetically, the median of Ph1+ mitoses declining from 100% to 66% with complete Ph1-suppression in one case. Of 46 late CP patients (greater than 12 months from diagnosis), 32 (70%) achieved CHR with interferon alone or combined with chemotherapy. All 10 patients with disease well controlled by chemotherapy obtained stable CHR with interferon alone. Of 36 partial responders to conventional chemotherapy, 22 (61%) obtained CHR on interferon plus low-dose hydroxyurea. Ph1 mosaicism was reached by 16 (35%) late CP patients (median Ph1+ cells 75%). Of nine accelerated phase patients on interferon plus chemotherapy, one attained CHR, and two responded partially. At a median follow up of 36 months, of 41 CHR patients in early CP, 15 are controlled on interferon, 12 have had autologous bone marrow transplantation (BMT), and two allogeneic BMT. Blastic transformation (BT) has occurred in eight of 41 CHR patients (19%) versus 17 of 30 (57%) non-responders and partial responders to interferon. At a median follow up of 22 months, of 32 late CP patients obtaining CHR, 26 remain on interferon, one had allogeneic BMT, one had autologous BMT, and one developed BT (versus five out of 14 with less than CHR). These studies confirm the haematological and cytogenetic efficacy of interferon in CML and indicate that the disease status at the start of treatment is critical in determining the success of therapy.

Combined Modality Therapy↗
PubMed1991

Role of interferon in lethality and lymphoid atrophy induced by Coxsackievirus B3 infection in mice.

To assess the importance of interferon (IFN) in the pathology of coxsackievirus B3 (CVB-3) infection, we evaluated both mortality rate and lymphoid involution in young adult BALB/C mice infected with lethal doses of the virus and treated either with anti-IFN antibody or with murine IFN-alpha/beta. Administration of antibody to IFN caused a profound worsening of the pathology and an increase in the mortality rate in infected animals. Treatment with murine IFN exerted a significant ameliorative effect on lethality when administered concomitantly with or soon after virus infection. The extent of this protection was correlated with the plasma levels of exogenous or endogenous IFN at 6 h postinfection, whereas no correlation with IFN titers was found later. The effects of IFN apparently were not directly mediated by antiviral effects, because at the times studied, no relation was found between IFN levels and virus titers, at least in the plasma of the infected animals. Lymphoid atrophy, assessed by measuring spleen weight, was only partially reversed by early IFN treatment. These data suggest that IFN production is critical during the early phases of infection, whereas it does not seem to play a significant protective role at later stages.

Animals↗
PubMed1991

Alterations of T-cell functions during Friend leukemia complex infection: defective signal transduction?

Proliferative and interleukin responses to T-cell mitogens such as concanavalin A (Con A) were rapidly and progressively reduced in BALB/c mice infected with the Friend leukemia complex (FLC) or its helper, Friend murine leukemia virus (F-MuLV). In contrast, a combination of the protein kinase C activator phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) and the Ca++ ionophore A23187 elicited a normal lymphoproliferative response up to 8 days postinfection (p.i.) and normal interleukin-2 (IL-2) and interferon-gamma responses up to day 14 p.i. Exogenous IL-2 failed to restore the lymphoproliferative response of infected cells regardless of the stimulation used. These results showed that the T-cell deficits may be at least partly attributable to a derangement of the signal transduction pathway leading to activation. Spleen cells passed through nylon wool columns reacquired a normal responsiveness to Con A +/- TPA up to 14 days p.i. The latter finding suggests that the alterations in signal transduction are not caused by primary defect of the responder-T cells but may result from an extrinsic suppressive mechanism.

Animals↗
PubMed1990

The biological basis for clinical use of interferon.

Interferons represent the body's most rapid defence against virus infection. Natural recovery from viral infections is correlated with interferon production; the inhibition of interferon enhances the severity of infection and interferon has been shown to protect animals from some viral infections. beta-Interferon is produced by fibroblasts in response to viral infection. Leucocyte (a) interferon may be induced by foreign or infected cells or by viruses, and it is continuously released into the bloodstream during infection, declining with time. gamma-Interferon are produced later in viral infection by virus-sensitized T lymphocytes. The antiviral action of interferon is induced by interaction with specific receptors on cell surfaces leading to translation of antiviral proteins. Interferons may also enhance immune responses by increasing expression of lymphocyte surface antigens and by increasing the cytotoxic activity of natural killer cells. In chronic hepatitis B and C, it seems likely that interferon's antiviral activity is responsible for the early fall of viral products, while its immunomodulatory activity is responsible for long-term effects, including the destruction of infected hepatocytes, with persistent loss of viral antigens and seroconversion.

Hepatitis, Viral, Human↗
PubMed1979

Large-scale production and physicochemical characterization of human immune interferon.

Large-scale production of crude high-titered (10(2.3) to 10(4) U/ml) human immune interferon (type II) was carried out in roller bottle cultures of human peripheral lymphocytes by using the T-cell mitogen staphylococcal enterotoxin A. Over 99% of human immune interferon was destroyed by pH 2 or heat at 56 degrees C for 1 h. The interferon was not neutralized by antibody to human leukocyte interferon. The kinetics of development of the antiviral state were slow for immune interferon relative to those for leukocyte interferon. Ultrogel AcA 54 chromatography of crude or the concentrated interferon resulted in two peaks of activity, a major one (87% of recovered activity) with a molecular weight of 40,000 to 46,000 and a minor peak of molecular weight 65,000 to 70,000. The column elution buffer consisting of 18% ethylene glycol and 1 M NaCl in phosphate-buffered saline resulted in at least 100% recovery of added interferon. The data suggest, then, that the interferon produced under large-scale conditions was immune (type II). The efficiency of the production was comparable to that described for large-scale production of human leukocyte interferon. Our large-scale production system for human immune interferon offers a feasible approach to preparation of large quantities of purified immune interferon for structure studies, antibody production, and clinical application.

Cell Line↗
PubMed1979

Enzymatic induction of interferon production by galactose oxidase treatment of human lymphoid cells.

Human lymphocyte cultures produced large amounts of interferon after treatment with the enzyme galactose oxidase. Interferon production was detectable as early as 3 h after enzymatic treatment and reached a level of about 10(4) reference units 20 to 24 h later. Galactose oxidase-induced interferon appeared to be immune interferon on the basis of acid lability, lack of neutralization by antibody to leukocyte interferon, and slow kinetics of activation of the cellular antiviral state. Interferon production was inhibited to the same extent (99%) by pretreatment of the cells with beta-galactosidase or with neuraminidase followed by beta-galactosidase, suggesting that the critical event for activation of interferon production is the oxidation of exposed galactose residues on lymphocyte membrane.

DNA↗
PubMed1979

Induction of an inhibitor of interferon action in a mouse lymphokine preparation.

An inhibitor of interferon action was identified in mouse lymphokine preparations. The inhibito was first detected in the supernatant fluid of mouse spleen cells at 72 h after stimulation by staphylococcal enterotoxin A. Inhibitor was not detected in supernatant fluids from unstimulated cultures. This inhibitor blocks the antiviral activity of both immune and fibroblast interferons. The inhibitor was purified 1,000-fold by two-step column chromatography. The partially purified inhibitor blocked the antiviral activity of up to 400 U of interferon. The immunosuppressive effect of interferon was also blocked by the inhibitor, suggesting that the inhibitor may modulate the immunoregulatory function of interferon.

Animals↗