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Biomedical subjects

J Wietzerbin

Publications and source records attributed to J Wietzerbin.

At least 91 records · Page 5Linked to original sources
PubMed1989

Intracellular alkalinization induced by amphotericin B derivatives in HL-60 leukemia cells.

The effects on intra- and extracellular pH of two polyenic derivatives of amphotericin B, N-fructosyl amphotericin B and N-fructosyl amphotericin B methyl-ester, were tested on HL-60 promyelocytic leukemia cells. Both derivatives raised the internal pH and reduced the external pH in weakly buffered medium. These results support the idea that both derivatives induce outward proton movement from the cell to the external solution. In this respect, the non-esterified derivative proved to be more powerful that the esterified one. Under the present conditions, there was little or no regulation of pH in HL-60 cells, which exhibited an almost constant pH gradient between the external and internal pH (acid inside relative to outside). This deficiency in pH homeostasis might be due to the immature state of the HL-60 cells.

Amphotericin B↗
PubMed1988

Interferon gamma is active on human lymphoblastoid Namalva cells without inducing an antiviral state.

We demonstrate the presence of high affinity receptors specific for interferon-gamma (IFN-gamma) in human lymphoblastoid Namalva cells. The presence of these receptors, whose binding affinity and cross-linking characteristics were not distinguishable from those of the corresponding receptors in sensitive cells, was not consistent with the lack of responsiveness of Namalva cells to IFN-gamma as regards growth inhibition, induction of 2'-5' oligoadenylate synthetase activity and inhibition of virus multiplication. Nevertheless, IFN-gamma enhanced the expression of two genes, HLA class II and c-myc. Although the mechanism of these IFN-gamma-mediated modifications is not understood, these results provide evidence that the IFN-gamma receptors present in Namalva cells are functional.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Recombinant tumor necrosis factors mediate platelet cytotoxicity to Schistosoma mansoni larvae.

The involvement of platelets in the immunity directed toward the parasite Schistosoma mansoni has been demonstrated in vitro and in vivo. The killing properties of platelets were shown previously to involve specific IgE after their binding to a membrane receptor. More recently, we have demonstrated that lymphokines released by S. mansoni Ag- or lectin-stimulated CD4+/CD8-T cells were able to induce the platelet cytotoxicity. The isoelectric focusing of the T lymphocyte supernatants showed that two factors were able to stimulate the platelet killing functions. One of them was clearly identified as being IFN-gamma. The present work demonstrates that the second lymphokine was TNF. Indeed the rTNF-beta and, to a lesser extent, rTNF-alpha, induce normal platelets into killer cells for the young larvae of schistosome. Moreover, an additive effect of the TNF-alpha and IFN-gamma has been observed.

Adult↗
PubMed1988

Interaction of 14C-labelled amphotericin B derivatives with human erythrocytes: relationship between binding and induced K+ leak.

Four 14C-labelled amphotericin B (Am B) derivatives with different net electric charges were examined: zwitterionic N-fructosyl Am B, positively charged N-fructosyl Am B methyl ester, negatively charged N-acetyl Am B and neutral N-acetyl Am B methyl ester. The binding of these four derivatives to human red cells and their octanol-water partition coefficients were measured. Simple partitioning between red cells and buffer was found for the four compounds, regardless of concentration, within a range of 10(-8) and 10(-4) M. This indicates the absence of cooperativity and saturability of binding at least in this concentration range. The constant partition coefficients were found to be three to five times higher for the two methyl ester derivatives than for the two non-esterified compounds. All partition coefficients were proportional to those found for the octanol-water system. Efficiency in inducing K+ leak from red cells was measured during the binding experiments. Despite the higher partition coefficients of the two methyl ester derivatives, they were found to have much lower ionophoric efficiency than the two non-esterified compounds. These results are discussed in terms of the mechanism of permeability pathway formation by polyene antibiotics.

Amphotericin B↗
PubMed1988

Recombinant human interferon-gamma induces increased IgE receptor expression on human platelets.

Human recombinant interferon-gamma (IFN-gamma) significantly increased the expression of receptors for IgE (Fc epsilon RII) on blood platelets. Fc epsilon RII was measured by specific binding of 125I-labeled IgE or flow cytometry experiments. Scatchard analysis of 125I-labeled IgE binding curves revealed that treatment with IFN-gamma increased the number of Fc epsilon RII but did not change the value of the association constant of Fc epsilon RII for 125I-labeled IgE. IFN-alpha had no effect on the expression or affinity of Fc epsilon RII. In addition to Fc epsilon RII, IFN-gamma also modified the expression of the glycoprotein IIb-IIIa complex on the platelet membrane.

Blood Platelets↗
PubMed1988

Interferon-gamma and tumor necrosis factor induce the L-arginine-dependent cytotoxic effector mechanism in murine macrophages.

We tested several monokines and muramyl dipeptide (MDP) to determine whether they induce the L-arginine-dependent effector mechanism in cultured murine macrophages. Recombinant interferon-gamma (rIFN-gamma) and recombinant tumor necrosis factor (rTNF) synergize to induce nitrite (NO2-) and nitrate (NO3-) synthesis from L-arginine as well as to cause inhibition of the iron-dependent enzyme aconitase in macrophages. Unlike rTNF, recombinant interleukin 1 (rIL 1) and rIL 6/B cell stimulatory factor 2 (rIL 6/BSF-2) did not act as cofactors when added to macrophages in the presence of rIFN-gamma. rIFN-gamma plus MDP induced the L-arginine-dependent effector mechanism in murine macrophages. However, induction by rIFN-gamma plus MDP was inhibited by anti-rTNF antibodies which suppressed both NO2-/NO3- synthesis and aconitase inhibition. This result indicates that endogenously produced TNF is involved in the induction of the L-arginine-dependent effector mechanism when MDP is the co-stimulant with rIFN-gamma. In contrast, anti-rTNF antibodies did not fully suppress the effect of combining rIFN-gamma and lipopolysaccharide, suggesting that, in this case, activation of the L-arginine-dependent effector pathway may involve more than induction of TNF synthesis by the macrophages. These results provide information, at a biochemical level, on a mechanism through which combination of IFN-gamma and TNF can modulate macrophage functions involved in the control of cell proliferation.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1988

Increased production of interferon gamma and tumor necrosis factor precedes clinical manifestation in multiple sclerosis: do cytokines trigger off exacerbations?

We have carried out a longitudinal study of interferon (IFN) and tumor necrosis factor (TNF) using a whole-blood mitogen stimulation assay in 20 multiple sclerosis (MS) patients and in a healthy control group. We set up individual profiles and the results were quite constant for each individual, both in healthy donors and in the patients in remission. Before exacerbations, however, we found an increase of IFN-gamma and TNF production preceding clinical symptoms by a maximum of 2 weeks. In benign cases, the increase disappeared rapidly, even before the appearance of symptoms, whereas we found sequelae whenever the increase persisted during weeks. In chronic progressive patients, we frequently found intervening increases. It may be that IFN-gamma and TNF trigger off exacerbations at a very early stage and that these cytokines may also play a role in maintaining disease in chronic progressive and invalidating forms.

Adult↗
PubMed1987

Induction of platelet cytotoxic functions by lymphokines: role of interferon-gamma.

Antigen- or mitogen-stimulated CD4+/CD- lymphocytes produced factors able to induce normal human platelets into cytotoxic effectors toward the young larvae of Schistosoma mansoni. The neutralization by monoclonal anti-IFN-gamma antibody of the induction of the platelet killer effect, the presence of IFN-gamma in the CD4+/CD8- lymphocyte supernatant, and, finally, the direct inducer effect of recombinant IFN-gamma clearly demonstrated that IFN-gamma was one of the factors responsible for the induction of platelet cytotoxic functions.

Adult↗
PubMed1987

Human platelets possess receptors for a lymphokine: demonstration of high specific receptors for HuIFN-gamma.

This report demonstrates that 125I-recombinant human interferon-gamma (125I-rHuIFN-gamma) binds to high-affinity specific receptors on human platelets. Scatchard analysis of binding data indicates the presence of homogeneous sites estimated in the order of 150 to 200, with an apparent equilibrium dissociation constant, Kd, of 2 X 10(-10) M. The binding of 125I-rHuIFN-gamma to platelet membrane was inhibited by unlabeled rHuIFN-gamma but not by unlabeled rHuIFN-alpha or unlabeled rHuIFN-beta. High affinity binding sites for HuIFN-alpha were not detectable. Cross-linking of 125I-rHuIFN-gamma to platelet membrane proteins with the use of a bifunctional agent (DSS) yielded a predominant complex of 100,000 +/- 5,000 daltons on SDS-PAGE autoradiography, which confirms the presence of specific receptors for IFN-gamma. Two faint bands of lower m.w., 70,000 and 90,000, could also be visualized. Cross-linking of 125I-rHuIFN-alpha to platelet surface could not be demonstrated by using the same procedures. This is the first time that a receptor for a lymphokine (IFN-gamma) has been demonstrated on human platelets. These findings are consistent with data already published, suggesting an interrelationship between IFN and platelet function.

Binding, Competitive↗
PubMed1986

Interferon-alpha, beta and -gamma induce (2'-5') oligoadenylate synthetase in cultured mouse brain cells.

Basal and interferon (IFN)-induced levels of (2'-5') oligoadenylate synthetase activity were measured in astrocyte cultures from the mouse cerebral cortex, in neurone-enriched and mixed cerebellar cultures, and in two continuous neural cell lines by a radioimmunoassay procedure. All untreated cultures contained measureable enzyme activity. Both purified IFN-alpha, beta and recombinant IFN-gamma induced the enzyme in all cultures with the exception of the C8S cell line which did not respond to IFN-gamma. IFN-alpha, beta was more effective than IFN-gamma. The amplitude of induction by IFN-alpha, beta was highest in the cell lines, intermediate in cortical astrocytes and lowest in mixed and neurone-enriched cultures from the cerebellum.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

Binding and cross-linking of recombinant mouse interferon-gamma to receptors in mouse leukemic L1210 cells; interferon-gamma internalization and receptor down-regulation.

Recombinant E. coli-derived murine IFN-gamma (Mu-rIFN-gamma; 5 X 10(7) U/mg) was radiolabeled with 125I by the chloramine-T method without loss of its antiviral activity. The 125I-Mu-rIFN-gamma showed specific binding to L1210 cells. Scatchard analysis indicates about 4000 binding sites per cell and an apparent Kd of 5 X 10(-10)M. Binding of 125I-Mu-rIFN-gamma to cells was inhibited by both natural (glycosylated) and rIFN-gamma, but not by IFN-alpha/beta. Receptor-bound 125I-Mu-rIFN-gamma was rapidly internalized when incubation temperature was raised from 4 degrees C to 37 degrees C. On internalization, almost no IFN-gamma degradation was observed during 16 hr incubation. 125I-Mu-rIFN-gamma binding capacity decreased in cells preincubated with low doses of unlabeled Mu-rIFN-gamma, but not with IFN-alpha/beta. This receptor down-regulation was dose-dependent: 90% reduction of 125I-Mu-rIFN-gamma binding was observed after preincubation with 100 U/ml. After removal of IFN-gamma from the culture medium, the binding capacity increased with time. However, reappearance of receptor was completely blocked by cycloheximide or tunicamycin, suggesting that re-expression of receptors is not due to recycling but to the synthesis of new receptors, and that the receptor is probably a glycoprotein. Cross-linking of 125I-Mu-rIFN-gamma to surface L1210 cell proteins by using bifunctional agents yielded a predominant complex of m.w. 110,000 +/- 5000. Thus, assuming a bimolecular complex, the m.w. of the receptor or receptor subunit would be close to 95,000 +/- 5000. The formation of such a complex appeared highly specific on the basis of the following criteria: it could be inhibited by the addition of Mu-rIFN-gamma but not by Mu-rIFN-alpha/beta, it was not obtained in cells pretreated with IFN-gamma to induce down-regulation of IFN-gamma receptors, and it was also identified in the IFN-alpha/beta-resistant L1210R cell line, known to be sensitive to IFN-gamma and which we have recently shown to express IFN-gamma receptors.

Animals↗
PubMed1986

Control of Ia antigen expression on phagocytic cells of the thymic reticulum by interferon-gamma and prostaglandins.

Phagocytic cells of the thymic reticulum (P-TR) spawned in the microenvironment of primary thymic stroma cultures express class II antigens on their membranes. We can show that Ia-antigen expression is regulated by the local secretion of interferon-gamma (IFN-gamma): (a) early primary culture supernatants contain IFN as tested by a cytopathogenic inhibition test after concentration of IFN activity; (b) the addition of a specific anti-IFN-gamma antiserum to primary cultures reduces Ia expression on P-TR suggesting that IFN-gamma produced in situ is implicated in Ia expression; (c) the percentage of Ia+ cells declines as primary cultures age. This phenomenon parallels the disappearance of thymocytes which are the supposed candidate for IFN-gamma secretion. (d) When isolated from their stromal environment and replated in secondary cultures, P-TR lose their membrane Ia antigen which can be re-expressed in the presence of recombinant IFN-gamma, but not IFN-alpha/beta. The decline of Ia expression on P-TR during the aging of primary cultures may be delayed by the inhibition of prostaglandin secretion.

Animals↗
PubMed1985

Characterization of antibodies against recombinant HuIFN-gamma produced by hybridoma cells.

Balbc/c mice were immunized with purified recombinant E. coli-derived human gamma-interferon (HuIFN-gamma). Their spleen cells were fused with a mouse myeloma cell line (Sp2/0). Hybridomas producing antibodies reacting with HuIFN-gamma were screened by a soluble-phase radioimmunoassay using pure 125I-labeled cloned IFN-gamma as antigen, and tested for their ability to neutralize the antiviral activity of IFN. Three hybridomas S1-1, S1-2, and S1-3, were cloned and subcloned and remained stable. Although the antibodies produced by clones S1-1 and S1-2 were both able to neutralize specifically the antiviral activity of natural and recombinant HuIFN-gamma, they appeared to recognize different epitopes on the HuIFN-gamma molecule. The antibodies produced by the S1-3 clone failed to neutralize the antiviral activity of either interferon. The antibodies from all three clones were characterized as IgG1 subclass. Their affinity constants were determined from competitive inhibition curves and ranged from 1 to 4.3 X 10(8) M-1.

Animals↗
PubMed1985

Syngeneic sensitization of mouse lymphocytes on monolayers of thyroid epithelial cells (TEC). VIII: Gamma interferon induced Ia antigen expression on TEC cultures.

We previously reported that the expression of Ia antigens on cultured monolayers of murine thyroid epithelial cells (TEC) occurred with a particular distribution exclusively on the basal part of the cultured thyroid cells, while class I antigens of the major histocompatibility complex (MHC) and thyroglobulin (Tg) are only detected on the apical surface. It appears that, 24 to 48 h after the deposition of syngeneic lymphocytes, Ia antigens are expressed on the apical side of cultured TEC, i.e. the surface that bears Tg and is in direct contact with the responder lymphocytes during syngeneic sensitization of T lymphocytes. We hypothesized that this phenomenon could represent, in syngeneic situations, the restriction process in antigen recognition by T cells, as demonstrated by I-A restricted primary syngeneic sensitization (PSS) on murine TEC. Moreover, we found that the addition of either PSS supernatants or gamma interferon (gamma IFN) to monolayers of TEC induced the expression of Ia antigens on the apical cell surface of these TEC cultures 24 to 48 h later. Taken together our data demonstrate that during the first hours of PSS, class II antigen and Tg are expressed on murine TEC cultures. This simultaneous expression of these antigens explains the strict in vitro I-A restricted PSS we previously observed.

Animals↗
PubMed1985

SLO4, a new interferon inducer isolated from Klebsiella pneumoniae and Escherichia coli.

A product isolated from Klebsiella pneumoniae and Escherichia coli, coded SLO4, has been shown to be effective in endogenous interferon induction in vivo in mouse when administered IP or IV, and in vitro with human leukocyte cultures. In these two systems induced interferon was defined. The inducer has not yet been characterized but seems not to belong to any components known to be interferon inducers such as viral particles, nucleic acids or endotoxins. An analytical study will be carried out to specify the constitution of this interferon inducer.

Animals↗