bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alterations in intracellular reactive oxygen species generation and redox potential modulate mast cell function
Authors: Wolfreys Karen , Oliveira David B. G. 
Published: March 2007

AbstractThe administration of mercuric chloride (HgCl2), gold compounds, or D‐penicillamine to Brown Norway (BN) rats causes a T helper (Th)2 cell‐associated autoimmune syndrome characterized by the production of a number of autoantibodies, marked elevation of serum IgE concentration, and tissue injury in the form of a vasculitis and arthritis. We have recently shown that the same compounds in vitro sensitize BN rat peritoneal mast cells for IgE‐triggered mediator release and interleukin‐4 mRNA production. We wished to test the hypothesis that these agents influence mast cell function via an effect on intracellular reactive oxygen species (ROS) production/redox balance. Mast cells were obtained from BN rats by peritoneal washout. Incubation with HgCl2, gold compounds or D‐penicillamine (the latter only in the presence of copper ions) led to the intracellular production of ROS as shown by the oxidative production of the fluorescent compound 2′,7′‐dichlorofluorescein. Mast cells were more sensitive than splenocytes to this effect. Direct oxidative stress (exposure to H2O2) produced a similar sensitization for mediator release to that caused by HgCl2. Inhibition of ROS formation by desferrioxamine or catalase diminished the enhancement of IgE‐mediated serotonin release caused by HgCl2, as did replenishment of intracellular glutathione. 2‐Mercaptoethanol exacerbated the toxicity of HgCl2, perhaps due to the formation of a lipophilic complex that enhanced HgCl2 uptake. Blocking of glutathione synthesis increased the toxicity of HgCl2, but also abolished any sensitizing effect on mediator release. These results support three main predictions of our hypothesis: (1) the compounds known to influence mast cell function all lead to the generation of ROS within the mast cell; (2) direct oxidative stress causes sensitization for mediator release by the mast cell; and (3) modulation of ROS production/redox balance within the mast cell modulates the effects of these compounds on mast cell function. The balance of oxidative/antioxidative influences may play an important role in the modulation of mast cell function, particularly in the context of chemically induced autoimmunity.
CD56bright natural killer cell subsets: Characterization of distinct functional responses to interleukin‐2 and the c‐kit ligand
Authors: Carson William E. , Fehniger Todd A. , Caligiuri Michael A. 
Published: March 2007

AbstractNatural killer (NK) cells are bone marrow‐derived large granular lymphocytes that express the CD56 surface antigen. The CD56bright NK subset represents approximately 10 % of all NK cells and is thought to be the least differentiated NK cell component in blood. The most mature NK cell expresses CD56 at low density and CD16 (FcRγIII) at high density, whereas CD56bright NK cells either lack CD 16 (CD56brightCD16−) or express it at low density (CD56brightCD16dim). c‐kit is a tyrosine kinase receptor which is expressed on both CD34+ hemato‐poietic precursor cells and CD56bright NK cells. In the current study, we characterize interleukin (IL)‐2 receptor (IL‐2R) and c‐kit expression in each of the CD56bright subsets. Both the CD56brightCD16− and CD56brightCD16dim NK subsets express the high‐affinity IL‐2R and the c‐kit receptor when isolated from fresh blood. However, each CD56bright NK cell subset has distinct functional responses to IL‐2, the c‐kit ligand (KL), or both. Activation of the high‐affinity IL‐2R on CD56brightCD16− NK cells induces a proliferative response that is significantly weaker than that observed in the CD56brightCD16dim NK cell subset. Incubation of the CD56brightCD16− NK cell subset with KL significantly enhances IL‐2‐induced proliferation, while KL has no such effect on the CD56brightCD16dim NK subset. Activation of the high‐affinity IL‐2R in both CD56bright subsets induces lymphokine‐activated killer (LAK) activity, but the addition of KL has no effect on LAK activity. Co‐stimulation of either CD56bright subset with IL‐12 and concentrations of IL‐2 that only saturate the high‐affinity IL‐2R induces substantial interferon (IFN)‐γ production. The addition of KL to this co‐stimulatory signal enhances IFN‐γ production in both CD56bright NK subsets. The distinct functional responses to IL‐2 and KL seen in the CD56brightCD16− and CD56brightCD16dim NK subsets provide insight into IL‐2R signaling and suggest that each phenotype identifies a discrete stage of NK cell differentiation.
Targeted elimination of cells expressing the high‐affinity receptor for IgE (FcϵRI) by a Pseudomonas exotoxin‐based chimeric protein
Authors: Fishman Ala , Lorberboum‐Galski Haya 
Published: March 2007

AbstractThe interaction between IgE and its high‐affinity receptor FcϵRI found on mast cells and basophils is the primary effector pathway in allergic response. To achieve a targeted elimination of cells expressing FcϵRI receptors, we constructed a chimeric protein in which a Fc fragment of mouse IgE is attached to a truncated form of Pseudomonas exotoxin (PE). To prepare the targeting moiety, we used a DNA sequence corresponding to amino acids 301–437, representing 30 residues of domain 2 and domain 3 of the mouse IgE constant region. This sequence was fused at the 5′ of a cDNA encoding PE40, a truncated form of PE lacking the cell binding domain. The chimeric protein, termed Fc2′−3−PE40, was expressed in Escherichia coli and partially purified. The protein is highly cytotoxic to mouse mast cell lines and bone marrow‐derived primary mast cells. This cytotoxicity is specific, as it could be blocked upon addition of whole IgE. Moreover, the protein had no effect on other cell lines of hemopoietic origin. The Fc2′−3−PE40 chimeric protein offers a new approach to the treatment of allergic disorders.
CD8 T cells from major histocompatibility complex class II‐deficient mice respond vigorously to class II molecules in a primary mixed lymphocyte reaction
Authors: Shimizu Takeyuki , Takeda Shunichi 
Published: March 2007

AbstractMature CD4+ and CD8+ T cells are restricted by major histocompatibility complex (MHC) class II and class I molecules, respectively. In a primary mixed lymphocyte reaction (MLR), CD8+ T cells from C57BL/6 (B6) mice can respond to allo‐class I molecules, but not allo‐class II molecules. However, a significant fraction of CD8+ T cells from C57BL/6 class II‐deficient (B6Aα−) mice violate this rule by responding vigorously in a MLR to class II molecules. The frequency of responding cells is ∼ 50 % of that of B6 CD8+ T cells responding to B6bm1 allo‐class I molecules. This response requires neither appropriate co‐receptor, i.e. CD4, nor exogenous lymphokines, indicating that interactions between the T cell receptors (TCR) and class II molecules are remarkably efficient. Since these CD8+ T cells are positively selected by class I molecules in the thymus of class II‐deficient mice, these CD8+ T cells should interact with both classes of MHC molecules. The absence of thymic negative selection by class II molecules may result in the production of these CD8+ T cells. The data imply that a substantial fraction of CD4+CD8+ double‐positive thymocytes in wild‐type mice interacts with both classes of MHC molecules prior to thymic selection.
Studies in vitro on the mechanism of the epithelial/mesenchymal interaction in the early fetal thymus
Authors: Shinohara Takashi , Honjo Tasuku 
Published: March 2007

AbstractThe effect of the mesenchyme on early thymus development was investigated in vitro by culturing tissue recombinants of the epithelium and mesenchyme derived from the earliest fetal thymus primordium. The thymus mesenchyme promoted the development of the epithelium as assessed by expression of epithelial surface molecules such as major histocompatibility complex (MHC) class I and class II antigens; mesenchymes of other organs were similarly effective. We looked for the culture conditions in which the epithelium could normally express the MHC class II antigen without the mesenchyme and found that the insulin‐like growth factors — I and — II were able to support epithelial development under serum‐free conditions. When we cultured the prospective thymus region of a day 9 embryo which had not initiated lymphoid precursor migration, MHC class II antigen was expressed on the epithelium, indicating that lymphoid precursors are not required for early epithelial differentiation. This system provides a means to dissect the complex tissue interactions during the earliest stages of thymus development.
Function of CD23 in the response of human B cells to antigen
Authors: Reljić Rajko , Cosentino Giovanna , Gould Hannah J. 
Published: March 2007

AbstractCo‐ligation of antigen receptor and complement receptor 2 (CD21) in the B cell membrane is important in the immune response to T‐dependent antigens. Four CD21 ligands have so far been identified, but only the activated products of the third component of complement (C3) are known to augment the immune response to specific antigens. The most recently discovered ligand for CD21 is CD23. We have generated a CD32+ CD23+ fibroblast cell line which presents a surrogate antigen (anti‐IgM) to human tonsil B cells in vitro. Incubation with these cells causes a 10‐ to 100‐fold reduction in the threshold concentration of anti‐IgM required for B cell proliferation. Anti‐CD19 further enhances the response to antigen and induces proliferation in the absence of anti‐IgM. Addition of soluble CD21 totally inhibits the effect of CD23, suggesting that CD21 mediates synergistic signaling by CD23.
Cytokine stimulation of T lymphocytes regulates their capacity to induce monocyte production of tumor necrosis factor‐α, but not interleukin‐10: Possible relevance to pathophysiology of rheumatoid arthritis
Authors: Sebbag Mireille , Parry Sarah L. , Brennan Fionula M. , Feldmann Marc 
Published: March 2007

AbstractPrevious studies in the laboratory have shown that the pro‐inflammatory cytokine tumor necrosis factor (TNF)‐α plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). The mechanisms involved in regulating monocyte/macrophage cytokine production are not yet fully understood, but are thought to involve both soluble factors and cell/cell contact with other cell types. We and others have previously demonstrated that T cells activated through the T cell receptor/CD3 complex induce monocyte TNF‐α production by contact‐mediated signals. In this report, we investigated further whether T cells activated by cytokines in the absence of T cell receptor stimulation also regulate monocyte cytokine production. T cells were activated in an antigen‐independent manner using the cytokines interleukin (IL)‐15 or IL‐2 alone, or in combination with IL‐6 and TNF‐α. Subsequently, T cells were fixed and incubated with monocytes. Fixed, cytokine‐stimulated T cells induced monocytes to secrete TNF‐α in a dose‐dependent manner, but did not induce secretion of IL‐10, a potent endogenous down‐regulator of TNF‐α and other pro‐inflammatory cytokines. Stimulation of monocyte TNF‐α was markedly inhibited when T cells were physically separated from monocytes within the tissue culture well, confirming that T cell contact is necessary. T cell acquisition of monocyte‐activating capacity was shown to be dependent on the period of cytokine stimulation, with T cells activated for 8 days more effective than T cells activated for shorter periods. Addition of interferon‐γ or granulocyte/macrophage colony‐stimulating factor to the T cell/monocyte cultures enhanced T cell induction of monocyte TNF‐α by threefold and ninefold, respectively. The results from this model of cognate interaction suggest that cytokine‐stimulated T cells, interacting with macrophages in the rheumatoid synovial membrane, may contribute to the continuous excessive production of TNF‐α observed in the RA joint, and to the imbalance of pro‐inflammatory cytokines over anti‐inflammatory cytokines.
Interleukin‐7 activates human naive CD4+ cells and primes for interleukin‐4 production
Authors: Webb Louise M. C. , Foxwell Brian M. , Feldmann Marc 
Published: March 2007

AbstractInterleukin (IL)‐4 is considered to be essential for T helper (Th)2 cell development, yet in areas of primary T cell activation, CD4+ cells are its only source. This implies that other signals must drive the initial expression of IL‐4 production. The role of CD28 co‐stimulation in Th2 subset development has been described. However, in mice deficient for CD28, Th2 responses are diminished, but not abrogated. Cytokines produced within the lymphoid tissue, e.g. IL‐7, may be important in the primary activation of naive CD4+ cells. We have found that human naive CD4+ cells purified from umbilical cord blood express the IL‐7 receptor and respond vigorously to IL‐7 during primary stimulation. Naive CD4+ cells grown in IL‐4, in the presence or absence of IL‐2, fail to produce Th2 cytokines upon restimulation. In contrast, IL‐7 induces development of a population of T cells that produce large amounts of IL‐4. Growth in IL‐7 also increases IL‐2‐induced production of interferon (IFN)‐γ and IL‐10 production. IL‐7‐induced IL‐4 production is not inhibited by neutralizing antibodies to IL‐4 on its receptor. This implies that IL‐7 acts directly to induce Th2 subset development and not by up‐regulating either production of IL‐4 during culture or expression of the IL‐4 receptor. Moreover, IL‐7 potentiates the effects of CD28 co‐stimulation on both naive CD4+ cell proliferation and subsequent IL‐4 production. Following primary stimulation, CD4+ cells lose expression of the IL‐7 receptor, resulting in IL‐7 unresponsiveness. This work reveals a novel role for IL‐7 in the primary activation of CD4+ cells. We propose that in conjunction with CD28 co‐stimulation, IL‐7 induces the initial expression of IL‐4 production and that IL‐4 acts subsequently to expand Th2 cytokine‐producing cells at the appropriate anatomical site.
Prevention of experimental autoimmune uveoretinitis by monoclonal antibody to interleukin‐12
Authors: Yokoi Hidetoshi , Kato Kazunori , Kezuka Takeshi , Sakai Jun‐Ichi , Usui Masahiko , Yagita Hideo , Okumura Ko 
Published: March 2007

AbstractExperimental autoimmune uveoretinitis (EAU) induced by immunization with interphotoreceptor retinoid‐binding protein (IRBP), a retinal self antigen, has been regarded to be a typical T helper type 1 (Th1)‐mediated inflammatory disease. In this study, we examined the effect of a neutralizing monoclonal antibody (mAb) to interleukin‐12 (IL‐12), which has been known to play a critical role in the Th1 differentiation, on the development of EAU. While 9 of 13 control mice developed EAU by the immunization with IRBP, none of 12 mice developed EAU when given anti‐IL‐12 mAb 1 day before immunization. These mice did not develop EAU even after a rechallenge with IRBP on day 30, indicating that a protective mechanism had been established by the anti‐IL‐12 treatment. The proliferative response of splenocytes to IRBP in vitro was not significantly impaired, but the production of IL‐2 and IFN‐γ was greatly reduced by the anti‐IL‐12 treatment. Moreover, production of IL‐5 and expression of IL‐4 mRNA were increased by the anti‐IL‐12 treatment. Consistently, IgG2a anti‐IRBP serum antibodies were decreased and IgG1 were increased. Administration of a neutralizing anti‐IL‐4 mAb at the time of IRBP rechallenge reversed the protection established by the anti‐IL‐12 treatment at the primary immunization. These results indicate that the anti‐IL‐12 treatment at the IRBP priming not only prevented the development of pathogenic Th1 cells, but also induced suppressive Th2 cells that protect the animals from further challenge with the same antigen.
Thymocyte activation induces the association of phosphatidylinositol 3‐kinase and pp120 with CD5
Authors: Dennehy Kevin M. , Broszeit Richard , Garnett David , Durrheim Glenda A. , Spruyt Louise L. , Beyers Albert D. 
Published: March 2007

AbstractCD5 is a glycoprotein expressed on thymocytes, T cells, and a subset of B cells. Antibody‐mediated cross‐linking studies or studies on CD5 knockout mice implicate CD5 as a co‐stimulatory or negative regulatory molecule. CD5 is rapidly phosphorylated on tyrosine (Y) residues following T cell activation. Y429 and Y441 occur in an imperfect immunoreceptor tyrosine‐based activation motif (ITAM)‐like sequence. We investigated whether phosphatidylinositol (PI) 3‐kinase, which binds to tyrosine‐phosphorylated ITAM, interacts with CD5 following T cell activation. PI 3‐kinase activity and the regulatory p85 subunit of PI 3‐kinase associated with CD5 in pervanadate‐stimulated, but not in unstimulated thymocytes. Cellular p85 as well as the recombinant Src homology 2 (SH2) domains of p85 bound a tyrosine‐phosphorylated peptide encompassing Y463 with approximately threefold greater affinity than a doubly tyrosine‐phosphorylated Y429‐Y441 peptide. Binding of the C‐SH2 domain to the Y463 phosphopeptide, together with preferential binding of the N‐SH2 domain to the Y429‐Y441 phosphopeptide, suggests a bivalent interaction. A 120‐kDa phosphoprotein (pp 120) associated with CD5 and specifically with the Y429‐Y441 phosphopeptide in stimulated thymocytes. We conclude that stimulation of thymocytes with pervanadate induces the recruitment of PI 3‐kinase and pp 120 to CD5.
Growth arrest of γδ T cells induced by monoclonal antibody against WC1 correlates with activation of multiple tyrosine phosphatases and dephosphorylation of MAP kinase erk2
Authors: Kirkham Paul A. , Takamatsu Haru‐Hisa , Parkhouse R. Michael E. 
Published: March 2007

AbstractWC1 is a 215‐kDa type 1 transmembrane glycoprotein, the expression of which is restricted to γδ T lymphocytes. The binding of an anti‐WC1 monoclonal antibody (mAb) (SC‐29) induces reversible growth arrest in proliferating interleukin (IL)‐2‐dependent γδ T lymphocytes and this study has examined the relevant biochemical mechanisms. WC1 binding activates multiple protein tyrosine phosphatases causing specific tyrosine dephosphorylation in the absence of calcium mobilization. One of the dephosphorylated proteins was identified as the MAP kinase erk2. Another phosphotyrosine protein of 70 kDa, found to coprecipitate with p85 phosphoinositol (PI)3‐kinase was either dephosphorylated or uncoupled from the p85 PI 3‐kinase immunoprecipitate after WC1 receptor binding by mAb SC‐29. The anti‐WC1‐induced tyrosine dephosphorylation was reversed by stimulation of γδ T cells with concanavalin A or anti‐CD3 mAb, demonstrating that at the biochemical level, mitogen stimulation is dominant to the growth‐arresting effects of anti‐WC1. It is therefore proposed that the activation of tyrosine phosphatases by WC1 binding and the resultant dephosphorylation of certain key signaling protein such as erk2 correlates with and may cause the induction of growth arrest in IL‐2‐dependent γδ T cells, without affecting the cells ability to respond to antigen. Possible mechanisms, which include the inhibition of IL‐2 signal transduction pathways, are discussed.
Interleukin‐10 prevents the generation of dendritic cells from human peripheral blood mononuclear cells cultured with interleukin‐4 and granulocyte/ macrophage‐colony‐stimulating factor
Authors: Buelens Christel , Verhasselt Valérie , De Groote Donat , Thielemans Kris , Goldman Michel , Willems Fabienne 
Published: March 2007

AbstractWe evaluated the effects of interleukin (IL)‐10 on the differentiation of dendritic cells (DC) obtained by culturing plastic‐adherent peripheral blood mononuclear cells for 7 days in presence of granulocyte/macrophage‐colony‐stimulating factor (GM‐CSF)+IL‐4. The addition of IL‐10 at the initiation of culture resulted in the generation of macrophage‐like cells with expressing high levels of CD14 and decreased levels of CD1a and CD1c. Furthermore, cells generated in presence of IL‐10 secreted lower levels of IL‐12, but higher levels of IL‐8 compared with DC generated in absence of IL‐10, both spontaneously and after CD40 engagement. Finally, cells generated in presence of IL‐10 were less efficient than DC in stimulating the production of IL‐2, interferon‐γ, and IL‐4 by allogeneic T cells. We conclude that IL‐10 prevents the generation of DC induced by GM‐CSF+IL‐4 and favors the development of macrophages with a lower T cell stimulatory potential, but secreting higher levels of IL‐8 than DC.
Interleukin‐10 and interleukin‐4 inhibit intracellular killing of Leishmania infantum and Leishmania major by human macrophages by decreasing nitric oxide generation
Authors: Vouldoukis Ioannis , Bécherel Pierre‐André , Riveros‐Moreno Valentina , Arock Michel , Da Silva Otamires , Debré Patrice , Mazier Dominique , Mossalayi M. Djavad 
Published: March 2007

AbstractThe host response to Leishmania infection is regulated by a specific pattern of local cytokine production. We investigated the effect of interleukin (IL)‐10 and IL‐4 on the leishmanicidal activity of human macrophages (Mϕ). As with L. major, intracellular killing of L. infantum by human Mϕ was obtained following ligation of surface CD23 or cell treatment with Interferon‐γ (IFN‐γ). This leishmanicidal activity required nitric oxide (NO) generation by activated Mϕ, and it was partially mimicked by cell treatment with chemical NO donors. Addition of recombinant human IL‐10 or IL‐4 to CD23 mAb or IFN‐γ decreased L. infantum and L. major killing by infected Mϕ. IL‐10 was more potent than IL‐4 in inhibiting the leishmanicidal activity of human Mϕ. Inhibition of Leishmania killing by IL‐4 and IL‐10 correlated with decreased NO generation from Mϕ, and was reversed when exogenous NO was added to cell cultures. Therefore, IL‐10 and IL‐4 down‐regulate leishmanicidal activity of human Mϕ, in part by inhibiting NO generation by these cells.
Cytotoxicity and weak CD40 ligand expression of CD8+ type 2 cytotoxic T cells restricts their potential B cell helper activity
Authors: Sad Subash , Krishnan Lakshmi , Chris Bleackley R. , Kägi David , Hengartner Hans , Mosmann Tim R. 
Published: March 2007

AbstractNaive CD8+ T cells differentiate into distinct cytokine‐secreting subsets: T helper (Th)1‐like cytotoxic T cells (Tc1) and Th2‐like Tc2. Although Th2 cells provide strong B cell help, we show that Tc2 cells secreting the same cytokines provide only modest B cell help for IgM production, and only when large numbers of B cells were stimulated with small numbers of Tc2 cells. Lack of effective B cell help by Tc2 cells was attributable partly to their cytotoxicity towards B cells. Both Tc1 and Tc2 cells killed small resting B cells mainly by a perforin‐dependent mechanism. In contrast to normal Tc2 cells, perforin‐deficient Tc2 cells failed to kill small resting B cells and induced IgM and IgG1 production, although their B cell help was significantly lower than that mediated by Th2 cells. This may be partly attributable to the ability of Tc2 but not Th2 cells to kill activated B cells even in the absence of perforin. Plate‐bound anti‐CD3 antibodies inhibited Tc2 killing of B cells and induced substantial immunoglobulin production. Additionally, Tc1 and Tc2 cells failed to express CD40 ligand (CD40L), whereas Th1 and Th2 cells expressed high levels of CD40L. Stimulation of Tc1 and Tc2 cells with plate‐bound anti‐CD3 antibodies for extended periods resulted in low‐level expression of CD40L. Proliferation of small resting B cells correlated with immunoglobulin production: proliferation was promoted strongly by Th1 and Th2, weakly by normal Tc1 and Tc2, and moderately by perforin‐deficient Tc1 and Tc2 cells. Thus, Tc2 cells may not contribute significantly to cognate B cell help during normal responses.