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J Favero

Publications and source records attributed to J Favero.

At least 37 records · Page 2Linked to original sources
PubMed1993

The retinoic acid analog CBS-211A potentiates the 1 alpha,25-dihydroxyvitamin D3-induced differentiation of U937 cells.

We report the effect of CBS-211A, a synthetic retinoid analog, designed for topical eye administration, on the growth and differentiation of myelomonocytic cells. This compound was assayed alone or in combination with 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3), since we previously evidenced a synergism of retinoic acid (RA) and 1 alpha,25(OH)2D3 in the induction of U937 cell differentiation. Unlike RA, CBS-211A neither affected the growth of myelomonocytic cells nor differentiated them. Nevertheless, when it was associated with 1 alpha,25(OH)2D3, CBS-211A strongly potentiated the 1 alpha,25(OH)2D3-induced inhibition of U937 cell proliferation and caused a dramatic increase in their differentiation toward monocytes/macrophages. The co-inducing effect of CBS-211A was restricted to U937 cells. Our data suggest that CBS-211A may have therapeutic implications in the treatment of certain kinds of myelomonocytic leukemia. CBS-211A also provides an interesting tool to understand the mechanisms involved in the differentiation of myelomonocytic cells.

Animals↗
PubMed1993

Effect of retinoic acid and vitamin D on the expression of interleukin-1 beta, tumour necrosis factor-alpha and interleukin-6 in the human monocytic cell line U937.

We have previously described a synergism between the two physiological hormones, retinoic acid (RA) and 1 alpha,25-dihydroxyvitamin D3 (VD) in the induction of U937 cell differentiation towards a more mature state. Herein, we investigated the regulation of cytokine production during RA and/or VD treatment of U937 cells. Cell differentiation was followed by measurement of their capacity to give oxidative responses, and interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and IL-6 gene and protein expression were determined in RA/VD-treated cells, activated or not with lipopolysaccharide (LPS). The undifferentiated and RA-treated U937 cells were unable to produce monokines even when they were stimulated by LPS. VD induced the monokine mRNA expression in U937 cells but failed to induce protein release. However, unlike RA, it primed the cells to secrete monokines upon endotoxin stimulation. A large enhancement of the production of the monokines both at mRNA and protein levels was observed in the U937 cells exposed to the combination of RA + VD. Nevertheless, protein release required a further step of activation of the RA + VD-primed cells. The co-inducer effect of RA and VD was not observed in HL-60 or THP-1 cells and seems to be restricted to U937 cells. These results on cytokine expression support our previous finding that a combination of RA and VD brings the U937 cells to a high stage of myeloid differentiation with major characteristics of monocytes/macrophages.

Blotting, Northern↗
PubMed1992

Contrasting effects of the protein kinase C inhibitor staurosporine on the interleukin-1 and phorbol ester activation pathways in the EL4-6.1 thymoma cell line.

EL 4-6.1 cells, variants of the murine EL4 thymoma cell line, can be activated by interleukin 1 (IL-1) or phorbol 12-myristate-13-acetate (PMA), or PMA+IL-1 to secrete interleukin 2 (IL-2) and interleukin 4 (IL-4) and to express the IL-2 receptor (IL-2R). To compare the different activation pathways, we examined the effects of staurosporine (STAR) and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), two protein kinase C (PKC) inhibitors, on the induction of interleukin secretion and IL-2R expression in these cells. We report here that nanomolar concentrations of STAR strongly potentiated (20- to 30-fold) the production of IL-2 or IL-4, when EL 4-6.1 cells were induced by IL-1 alpha (or IL-1 beta) alone. By contrast, at identical concentrations, STAR dose-dependently inhibited the production of IL-2 and IL-4 resulting from PMA or PMA+IL-1 cell treatment. STAR also negatively affected the expression of IL-2R, which was dependent on PMA-sensitive PKC with either IL-1, PMA, or PMA+IL-1 stimulation. The changes in interleukin production and IL-2R expression in EL 4-6.1 activated cells were correlated with changes at the mRNA level measured by quantitative polymerase chain reaction (PCR). This finding suggests a pretranslational effect of the drug. At micromolar concentrations, H7 showed the same effects as STAR, but only increased IL-1-triggered interleukin secretions twofold. We observed that the action of PKC inhibitors did not result from modification of IL-1 receptor (IL-1R) expression in EL 4-6.1 cells. Thus, our data show that PKC inhibitors clearly distinguish between IL-1 and PMA stimulatory pathways. In addition, they suggest that the IL-1 stimulatory pathway involves PKC(s) [or other undefined kinase(s)] which regulate this pathway and differ from PKC(s) activated by PMA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Hypoxia/reoxygenation stimulates endothelial cells to promote interleukin-1 and interleukin-6 production. Effects of free radical scavengers.

Vascular endothelium produces and/or interferes with various cytokines. Previous studies have demonstrated interactions of these inflammatory and immunological mediators with oxygen-derived free radicals. The present work examines the relationship between hypoxia/reoxygenation (H/R) and cytokine production by cultured endothelial cells. Human umbilical vein endothelial cell (HUVEC) monolayers were incubated for 24 h in normoxia or submitted to 5 h hypoxia/19 h reoxygenation. Then, interleukin-1 (IL-1) alpha and beta, and interleukin-6 (IL-6), were measured in culture supernatants by specific enzyme immunoassays and bioassays, respectively. Under these conditions, the spontaneous production of IL-1 and IL-6, detected in normoxic HUVEC, greatly increased after H/R treatment. The observed enhancement was cycloheximide-sensitive and, consequently, reflected a de novo protein synthesis. Superoxide dismutase and glutathione peroxidase prevented H/R-induced IL-1 and IL-6 increase. These results constitute the first demonstration that H/R stimulates HUVEC to promote IL-1 and IL-6 production and strongly suggest a role for oxygen-derived free radicals in the cytokine synthesis.

Cell Hypoxia↗
PubMed1990

Lymphocyte mitogenesis and CD4 modulation induced by different phorbol esters: comparative studies.

Phorbol 12-myristate 13-acetate (PMA) can stimulate T-cells via its binding to protein kinase C (PKC). Such a phenomenon occurs when a threshold of concentration as low as 1 nM of PMA is reached. Other phorbol esters possess the ability to stimulate lymphocytes but at higher thresholds of concentration. We show here that the different phorbol ester concentrations needed to induce stimulation and proliferation, estimated by both interleukin-2 receptor (IL-2R) expression and DNA synthesis, correspond very closely to those inducing the modulation of CD4 antigen, confirming a direct relationship between CD4 down-regulation and cellular activation. We estimated the structural features of these different phorbol derivatives in relation to lymphocyte activation and CD4 modulation, and confirm that the ester side chains which give to the phorbol ester derivatives their lipophilic character, discriminate, according to their length, the ability of the different compounds to reach their receptor inside the cell membrane; we also brought some evidence that the polar phorbol nucleus of these compounds is probably responsible for their interaction with the membrane receptor mainly through the hydroxyl group in the C4 position.

Adult↗
PubMed1989

Anti-CD4 monoclonal antibodies enhance phorbol 12-myristate, 13-acetate-induced activation of human T cells.

Evidence exists which indicates that the T cell differentiation molecule CD4 may interact with nonpolymorphic determinants of major histocompatibility complex (MHC) class II antigens on accessory cells to stabilize the formation of a ternary complex formed by the T cell receptor (CD3-TcR), antigen, and MHC class II restriction element. However, there is also evidence which suggests alternative or additional functional roles of CD4 in the delivery of signals to T cells independent of MHC class II recognition. In the present study, we examined different anti-CD4 monoclonal antibodies (mAbs) for their ability to influence lymphocyte proliferation induced by phorbol 12-myristate, 13-acetate (PMA). We found that the response of human peripheral blood mononuclear cells to PMA could be enhanced by some anti-CD4 mAbs (OKT4, OKT4A) but not by others (G17-2). This enhancement was due neither to a direct action of the mAbs on the monocytes nor to intercellular crosslinking through an Fc-Fc receptor interaction. We also found that the binding of anti-CD did not influence the down-regulation of CD4 expression induced by PMA, ruling out any correlation between increased stimulation and CD4 modulation. Our results, taken together with those recently published on the ability of a soluble anti-CD4 mAb (B66) to induce lymphocyte activation by itself, provide evidence that CD4 antigen plays a positive functional role in T cell stimulation in addition to stabilizing the antigen-antigen receptor interaction.

Antibodies, Monoclonal↗
PubMed1988

Determination of mitogenic properties and lymphocyte target sites of Dolichos lablab lectin (DLA): comparative study with concanavalin A and galactose oxidase cell surface receptors.

A mannoside-directed lectin has been isolated and purified from the seeds of Dolichos lablab L. by affinity chromatography. We have established that this glycoprotein, which displays high erythroagglutinating activity without blood group specificity, highly activates murine T lymphocytes, and we have described for the first time its mitogenic properties. Although its main properties are close to those of concanavalin A (Con A), the well-known mannoside-directed mitogen devoid of sugar moiety, several differences were found in some of the early events triggered by the two lectins during lymphocyte mitogenic stimulation: higher level of interleukin-2 (IL-2) synthesis, optimal dose for IL-2 synthesis at suboptimal mitogenic concentration, lack of ecto-5' nucleotidase inhibition, and lack of mitogenic inhibition at high lectin concentration. Because the two lectins did not act on the cell surface in exactly the same way, we have compared their receptors involved in mitogenesis on the plasma membrane of murine lymphocytes. We had previously established that the polyclonal activation of these cells probably occurred through high-molecular-weight receptors (200-230 kDa). Since the mitogenic stimulation of lymphocyte by galactose oxidase (GO), like that of Con A, was inhibited by DLA, we analyzed the cell surface receptors that were common to these three polyclonal mitogens. After labeling the neuraminidase/GO-treated cell surface glycoproteins with NaB3H4, we immunoprecipitated the Con A and DLA receptors which are the target of GO mitogenic action. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the precipitates demonstrated that there exist on the lymphocyte cell surface receptors common to the polyclonal mitogens DLA, Con A, and GO. Because Con A and DLA sterically inhibit GO mitogenic stimulation, the common glycoproteins which represent the necessary sites of oxidative mitogenic action are probably those which are involved in DLA and Con A-triggered mitogenesis, despite the different properties of the two lectins. These differences could be explained by the lower molecular weight receptors of the two lectins which are not identical.

5'-Nucleotidase↗
PubMed1986

Enhancement of cell-cell contact by a nonmitogenic lectin increases blastogenic response and IL-2 release by mitogen-stimulated mouse thymocytes.

We have examined the influence of peanut agglutinin (PNA), a lectin which agglutinates but does not stimulate mouse thymocytes, on the responsiveness of these cells to concanavalin A (Con A) or galactose oxidase stimulation. Binding low amounts of PNA on unseparated mouse thymocytes pretreated with neuraminidase highly enhances the mitogenic response and the level of interleukin 2 release in the culture medium upon Con A stimulation. We have shown that PNA present on the cell surface acts as a crosslinking agent which favors intercellular binding between accessory cells (macrophages) and thymocytes, leading through this enhanced cooperation by cell-cell contact to an enhanced blastogenic response.

Adjuvants, Immunologic↗
PubMed1986

Mechanism whereby ouabain inhibits human T lymphocyte activation: effect on the interleukin 2 pathway.

Through the blockade of the Na-K-ATPase, ouabain inhibits several biochemical and biological events leading to the proliferation of activated lymphocytes. Since we already found that interleukin 1 production was not prevented by ouabain, we investigated by which mechanism this drug inhibits mitogen-induced human T lymphocyte activation, with respect to the interleukin 2 (IL 2) pathway. Our data revealed that at concentrations lower than 0.2 microM, IL 2 accumulation was not reduced in ouabain-treated cultures, even when cell proliferation was completely inhibited (0.1-0.2 microM ouabain). Moreover, in this concentration range, ouabain stimulated in a dose-dependent manner the accumulation of IL 2 in the supernatant of Con A-stimulated lymphocytes (optimum for 0.05 microM corresponding to half inhibition of lymphocyte proliferation). Such an effect, which appears correlated to the inhibition of Na-K-ATPase, suggests a failure of the cell to utilize IL 2. At concentrations higher than 0.3 microM, ouabain inhibited both lymphocyte proliferation and IL 2 production. These observations show that the glycosteroid interacts differently with the different cell populations involved in the cascade of reactions leading to cell proliferation, and suggest that the mitogenic inhibition resulting from the blockade of Na-K-ATPase is not related to the blockade of IL 2 production. On the other hand, we observed that: ouabain inhibited the expression of the receptors for IL 2, an obligatory step in lymphocyte proliferation; ouabain blocked the proliferation of an IL 2 sensitive human T cell line; in both cases the inhibition paralleled that of lymphocyte proliferation. Our data suggest that the essential steps of lymphocyte proliferation in which Na-K-ATPase-dependent K+ fluxes play a critical role are the expression of IL 2 receptors and the IL 2-dependent proliferative step.

Cell Line↗
PubMed1984

The proposed 5'-nucleotidase inhibitor in human leukemic cells is an artefact.

It is now well established that human lymphoblastoid cell lines showing immaturity characters display ecto-5'-nucleotidase activities lower than normal levels. A recent paper (Sun, A.S., Holland, J.F. and Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577-584) mentioned that this phenomenon resulted from the presence of a 5'-nucleotidase inhibitor in these cell lines. We demonstrate here that the use of 5'-[3H]AMP as a substrate, and inadequate analysis of the products formed, led them to a misinterpretation. [3H]Adenosine derived from 5'-[3H]AMP hydrolysis was further transformed into [3H]inosine by the adenosine deaminase activity of the leukemic cell lines tested; [3H]inosine was precipitated with the excess substrate and was not taken into account in the ecto-5'-nucleotidase determination, which led the authors to confuse this adenosine deaminase activity with a 5'-nucleotidase inhibitor. We did not observe 5'-nucleotidase inhibition by leukemic cell cytosol when convenient assay methods were used and showed that the presence of such an inhibitor remains to be established.

5'-Nucleotidase↗
PubMed1984

Paradoxical production of mouse thymocyte activating factor by ouabain-treated human mononuclear cells.

At concentrations as low as 10(-7) M, the cardiotonic glycosteroid ouabain, a specific inhibitor of the membrane Na+, K+-ATPase, is known to inhibit in vitro human lymphocyte proliferation produced in mixed lymphocyte cultures or induced by various stimulating agents (PHA, Con A, PWM, soluble antigens), while mouse lymphocyte proliferation is unaffected at this concentration. Ouabain inhibits most of proliferative response parameters at all stages of the transformation. This observation prompted us to suggest that ouabain could also act through inhibition of interleukin production which is known to occur during the first hours after T-cell stimulation in the presence of monocytes. In order to check the possible influence of ouabain on interleukin production, conditioned media from stimulated human mononuclear cells, prepared in the presence or in the absence of inhibitor, were tested for their ability to promote a mouse thymocyte response to PHA. Instead of the expected inhibition, we found that ouabain, even at high concentrations (2 X 10(-6) M) enhanced the stimulatory effect and/or the production of murine thymocyte activating factor(s). Moreover conditioned media from serum-free cultures of unstimulated human mononuclear cells exposed for 24 hr to low ouabain concentrations (10(-8) to 10(-7) M) showed a high activating effect on the response of murine thymocytes to PHA. This soluble factor produced upon ouabain treatment is produced by adherent cells and appears to be functionally similar to interleukin 1.

Animals↗
PubMed1984

Characterization of peanut agglutinin receptors of murine thymocytes.

Murine thymocytes can be separated on the basis of their agglutinability by peanut agglutinin (PNA) into two broad subpopulations assimilated to immunoincompetent agglutinated PNA+ cells and immunocompetent nonagglutinated PNA- cells. Seven surface membrane components have been isolated by immunoprecipitation using rabbit anti-PNA IgG and Staphylococcus aureus bearing protein A, from PNA-coated radiolabeled immature cells. These components (apparent molecular weights of 180, 175, 130, 115, 65, 26, and 23 kDa) labeled by the galactose oxidase/tritiated sodium borohydride method and by 125I-iodination are glycoproteins which are PNA-receptor sites normally exposed on the surface membrane of PNA+ thymocytes. The nonagglutinated PNA- cells also possess on their surface unmasked receptors for the lectin (175-180 kDa) but in lower amounts. Neuraminidase treatment prior to galactose oxidase/tritiated sodium borohydride labeling shows that the majority of PNA receptors is present on the PNA-thymocyte surface but are masked by sialic acid residues on the terminal position of the oligosaccharidic chains.

Animals↗
PubMed1983

Cell affinity chromatography with ligands immobilized through cleavable mercury-sulfur bonds.

A new methodology for cell separation by affinity chromatography is described. We have conjugated the organomercurial mersalyl to trisacryl beads bearing primary amino groups. Thiolated ligands can be immobilized on this matrix through cleavable Hg-S bonds. Two model studies of cell separation are reported: (i) concanavalin A thiolated with N-succinimidyl-3-(2-pyridyldithio)-propionate and immobilized on mersalyl-trisacryl; mouse thymocytes bound to Con A-mersalyl-trisacryl were eluted from the support by short thiol treatment which preserved cell viability; (ii) anti-dinitrophenyl antibodies modified with S-acetyl-mercaptosuccinic anhydride and immobilized on mersalyl-trisacryl; sheep erythrocytes, previously labelled with trinitrobenzene sulfonic acid, bound to this support and were easily recovered by thiol treatment without hemolysis. This methodology should overcome difficulties frequently encountered in cell affinity chromatography. Cell support multivalent interactions or high affinity of cell-ligand bindings often require drastic elution conditions which prevent viable cell recovery.

Animals↗