bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interleukin‐7 induces T cell proliferation in the absence of Erk/MAP kinase activity
Authors: Crawley James B. , Willcocks Joannie , Foxwell Brian M. J. 
Published: March 2007

AbstractInterleukin (IL)‐7 and IL‐2 are important lymphoproliferative cytokines which both use the γc chain as part of their respective receptors. To learn more of their signaling mechanisms a comparison was made of the patterns of intracellular tyrosine phosphorylated proteins induced by these cytokines in the murine T cell line, CT6. Several similarities were revealed in the tyrosine phosphorylated proteins induced. However, a notable subset of proteins of mainly < 60 kDa were only phosphorylated by IL‐2. Characterization of the two most prominent bands of this subset, pp54 and pp42, revealed these to contain Shc and p42MAP/Erk kinase, respectively. Further studies confirmed that IL‐7 was unable to induce the phosphorylation of either the p44MAP/Erk or p42MAP/Erk or activation of the kinases. Shc is involved in activation of p21ras, a key event in the signaling cascade, via p72raf and MEK, leading to MAP/Erk kinase (MAPK) activation. These data indicate that this pathway is not utilized by IL‐7 and may not, therefore, be essential for cytokine‐driven T cell proliferation. This possibility was supported by studies with the MEK inhibitor PD098059, which had no selective effect on CT6 proliferation induced by IL‐2 as compared with IL‐7, although the drug completely inhibited MAP/Erk phosphorylation induced by IL‐2.
Mouse mammary tumor virus production by thymic epithelial cells in vivo
Authors: Nabarra Bernadette , Desaymard Catherine , Waché Anne‐Claude , Papiernik Martine 
Published: March 2007

AbstractExogenous mouse mammary tumor viruses (MMTV) replicate in the mammary glands of infected females, and so infect the suckling pups. We have previously shown that the virus is rapidly disseminated to all the lymphoid organs, including the thymus. The present electron microscope immunohistochemical study describes the viral production site in the thymus. Viral buds and viral proteins were restricted to the thymus medullary epithelial cells. MMTV‐encoded proteins were identified on the free viral particles and on the budding ones, the ribosomes, the membrane of the endoplasmic reticulum, and on the membrane of the medullary type II epithelial cell vacuolar network. The thymus medullary epithelial cells can thus integrate the virus and allow viral replication. The results support earlier results indicating that in some experimental conditions, epithelial cells may be involved in MMTV‐induced negative selection by showing that thymic epithelial cells do express MMTV‐encoded proteins.
Loss of the β1 subunit of the sodium pump during lymphocyte differentiation
Authors: Masat Linda , Cascalho Marilia , Wabl Matthias 
Published: March 2007

AbstractThe Na, K‐ATPase, or sodium pump, is responsible for maintaining cellular volume and is involved in receptor‐mediated endocytosis; it is a ubiquitous transmembrane enzyme in higher eukaryotes and consists of an α and a β subunit. In the mouse, two isotypes of β with no known function have been identified: β1 and β2. We have studied the expression of β1 and β2 in lymphocytes from bone marrow, spleen, peripheral blood, and thymus. The β2 subunit is not expressed in any of the lymphocytes tested. Pre‐B lymphocytes and the majority of mature, resting B cells in the bone marrow express the β1 subunit, as do all pre‐T cells and mature thymocytes. In the spleen and in blood, β1 expression defines subsets of T and B lymphocytes. Mitogen‐stimulated T and B cells lose β1 expression and do not express β2. While there is no indication that there is a change in α subunit isoform expression as a result of lymphocyte activation or that it is expressed in smaller amounts, there is a switch in the expression of the β isoform.
Monovalent single‐chain Fv fragments and bivalent miniantibodies bound to vesicular stomatitis virus protect against lethal infection
Authors: Kalinke Ulrich , Krebber Anke , Krebber Claus , Bucher Etienne , Plückthun Andreas , Zinkernagel Rolf M. , Hengartner Hans 
Published: March 2007

AbstractSeveral antibody‐dependent mechanisms have been postulated to mediate neutralization of different animal viruses, including blocking of docking to receptors, induction of conformational changes in the virus coat, and Fc‐dependent opsonization. We have studied the molecular requirements for antibody‐mediated neutralization of vesicular stomatitis virus (VSV) in vitro and protection against lethal disease in vivo with a single‐chain Fv fragment (scFv) and the corresponding bivalent miniantibody (scFv‐dHLX) generated from a VSV‐neutralizing monoclonal antibody. Both monovalent scFv and bivalent scFv‐dHLX miniantibodies were able to neutralize VSV in vitro and to protect interferon‐αβ receptor‐deficient (IFN‐αβR−/−) mice against lethal disease after intravenous injection of 50 plaque‐forming units (pfu) VSV pre‐incubated with the scFv reagents. Similarly, severe‐combined immunodeficient (SCID) mice infected with immune complexes of 108 pfu VSV and bivalent scFv‐dHLX were protected against lethal disease; however, mice infected with immune complexes of 108 pfu VSV and monovalent scFv were not. Although repeated scFv‐dHLX treatment reduced virus quantities in the blood, neither SCID nor IFN‐αβR−/− mice were protected against lethal disease after passive immunization and subsequent VSV infection. This was due to the short half‐life of 17 min of scFv‐dHLX in the circulation. These data demonstrate that neutralization of VSV and protection against lethal disease do not require Fc‐mediated mechanisms and that cross‐linking is not crucial for protection against physiologically relevant virus doses in vivo.
Dual T cell receptor T cells have a decreased sensitivity to physiological ligands due to reduced density of each T cell receptor
Authors: Blichfeldt Erik , Munthe Ludvig André , Røtnes Jan Sigurd , Bogen Bjarne 
Published: March 2007

AbstractA considerable fraction of T cells express two distinct T cell receptors (TCR), mainly due to expression of two TCR α chains. It has been suggested that such dual‐TCR cells could have a role in autoimmunity. However, as such cells express less of each TCR, they could be less sensitive to their physiological ligand, i.e. peptide plus major histocompatibility complex molecules (MHC). We tested this hypothesis in a transgenic TCR model in which most T cells express different amounts of the transgene‐encoded TCR, due to expression of endogenous TCR α chains. Five Th1 clones derived from λ2315 immunoglobulin light chain‐specific TCR‐transgenic mice expressed different levels of the transgene‐encoded TCR, ranging from ∼ 10000 to ∼ 50000 TCR per cell. Cytosolic Ca2+ mobilization in single T cells from these clones elicited by λ2315 peptide‐pulsed, I‐Ed‐expressing antigen‐presenting cells, correlated linearly with the relative transgene‐encoded TCR expression. The peptide requirement for half‐maximal T cell proliferation showed a similar correlation, with low TCR levels requiring higher peptide concentration. Corroborative evidence was obtained by deployment of short‐term polyclonal CD4+ lines from TCR‐transgenic mice. Such lines had reduced early (Ca2+ mobilization) and late (lymphokine and proliferation) responses, compared with T cell lines from recombination‐deficient TCR‐transgenic severe combined immunodeficiency mice (which express only a single transgene‐encoded TCR). Taken together, the Ca2+ responses increase gradually with increasing TCR expression per cell, similar to the previously described analog Ca2+ signaling elicited by increasing amounts of peptide/MHC [Røtnes et al., Eur. J. Immunol. 1994. 24: 851]. Surprisingly small reductions in TCR expression per cell reduce T cell responsiveness. This suggests that dual‐TCR T cells are immunologically less effective than single‐TCR T cells.
Antigen‐independent responsiveness to interleukin‐4 demonstrates differential regulation of newborn human T cells
Authors: Early Eavan M. , Reen Denis J. 
Published: March 2007

AbstractThe low incidence of graft‐versus‐host disease following clinical use of umbilical cord blood compared to adult bone marrow as a source of stem cells for bone marrow reconstitution, leads to questions concerning the level of immunocom‐petence of newborn T cells. The maturation and functional status of newborn CD4+ T cells, which are almost exclusively CD45RA+ naive T cells, compared with their adult phenotypic counterparts, is poorly understood. We examined the proliferative response to mitogens and cytokines of CD4/CD45RA+ T cells from adults and newborns, with and without accessory cells. Newborn CD4/CD45RA+ T cells demonstrated a distinct proliferative response profile which was determined by the number of accessory cells present in co‐cultures with various stimuli. Newborn CD4/CD45RA+ T cells were particularly responsive to interleukin (IL)‐4, IL‐4 plus anti‐CD2 monoclonal antibodies (mAb) and IL‐4 plus phytohemagglutinin (PHA), whereas adult CD4/CD45RA+ T cells were unresponsive under similar conditions. The mitogenic responses of newborn and adult CD4/CD45RA+ T cells to PHA and anti‐CD2 mAb, which were equivalent, were directly proportional to the number of accessory cells present, whereas the responsiveness to cytokines was inversely proportional to the number of co‐cultured accessory cells. Anti‐CD2 responses were much more sensitive to low numbers of accessory cells than PHA. The particular sensitivity of newborn CD4/CD45RA+ T cells to IL‐4 represents an antigen‐independent T cell activation response which could help promote a Th2 immune response resulting in the newborn.
Thiols prevent Fas (CD95)‐mediated T cell apoptosis by down‐regulating membrane Fas expression
Authors: Delneste Yves , Jeannin Pascale , Sebille Eric , Aubry Jean‐Pierre , Bonnefoy Jean‐Yves 
Published: March 2007

AbstractThiol antioxidants have been shown to protect cells against apoptosis. Based on the role of Fas in T cell apoptosis, we investigated the effect of thiols on Fas expression. We report that the thiol N‐acetyl‐L‐cysteine (NAC) prevents the induction of Fas on human peripheral blood T cells in a dose‐dependent manner. It also down‐regulates in a time‐ and dose‐dependent manner Fas expression on Fas‐expressing T cells. Although these effects were not mediated through de novo glutathione synthesis, only compounds with a free thiol group decreased membrane Fas expression. The decrease of Fas expression induced by NAC was not associated with a modulation of Fas mRNA transcription nor with an inter‐nalization, suggesting that NAC may affect the processing of Fas. Indeed, a soluble immunoreactive form of Fas was detected by ELISA and by Western blotting in the supernatants of Fas‐expressing T cells treated with NAC. As a functional consequence, NAC partly protected Jurkat cells against Fas‐mediated apoptotic cell death. Thus, this study shows that, by regulating Fas expression, the cytoprotective properties of NAC can be extended to Fas‐mediated cell death.
Tumor necrosis factor receptor p55 mediates deletion of peripheral cytotoxic T lymphocytes in vivo
Authors: Speiser Daniel E. , Sebzda Eric , Ohteki Toshiaki , Bachmann Martin F. , Pfeffer Klaus , Mak Tak W. , Ohashi Pamela S. 
Published: March 2007

AbstractCellular death of activated lymphocytes down‐regulates immune responses and is involved in maintaining self tolerance. Signals associated with ligation of the membrane molecule Fas lead to lymphocyte apoptosis, but additional, Fasindependent mechanisms have been postulated. Here, we show a marked expansion and prolonged persistence of functional activated cytotoxic T cells in mice lacking the tumor necrosis factor (TNF) receptor p55. In the absence of this receptor, peripheral lymphocyte apoptosis was significantly reduced in vivo. The prolonged thymocyte survival was associated with functional anergy, since the T cells no longer proliferated in vitro when stimulated with peptide antigen. However, specific cytotoxic effector function was easily detected in vitro. We conclude that the TNF receptor p55 is involved in peripheral T cell deletion in vivo.
Restricted appearance of self‐reactive clones into T cell receptor intermediate cells in neonatally thymectomized mice with autoimmune disease
Authors: Moroda Tetsuya , Iiai Tsuneo , Kawachi Yasuyuki , Kawamura Toshihiko , Hatakeyama Katsuyoshi , Abo Toru 
Published: March 2007

AbstractNeonatally thymectomized (NTx) mice fall victim to such autoimmune diseases as gastritis and pancreatitis with aging. Self‐reactive T cell clones are known to be consistently generated through TCR intermediate (i.e. TCRint) cell differentiation in normal mice (i.e. via the extrathymic pathways and an alternative intrathymic pathway). It was investigated whether the generation of such clones in NTx mice follows this rule or whether they are generated by default via mainstream T cell differentiation in the thymus. The majority of T cells generated in NTx mice were TCRint cells in all organs tested. In contrast to athymic mice, which carry only TCRint cells with aging, a leaky appearance of high TCR (i.e. TCRhi) cells emerged in the lymph nodes and other organs of NTx mice. Self‐reactive clones estimated by anti‐Vβ monoclonal antibodies in conjunction with the Mls system were confined to TCRint cells in all tested organs, including a target organ, the stomach, in NTx mice. A leaky population of TCRhi cells did not contain a significant number of self‐reactive clones. Moreover, such self‐reactive clones among TCRint cells in NTx mice with autoimmune disease were shown to be nonanergic in the proliferation assay. The present results suggest that the generation of self‐reactive clones is totally due to TCRint cell differentiation, although it is still undetermined whether the expanding TCRint cell population is generated via the extrathymic pathway or an alternative intrathymic pathway. It is shown here not to be due to a failure of the TCRhi cell‐differentiation pathway in NTx mice.
Genetic control of anti‐idiotypic vaccination against coronavirus infection
Authors: Yu Mathilde W. N. , Lemieux Suzanne , Talbot Pierre J. 
Published: March 2007

AbstractThe idiotypic network can be experimentally altered to induce protective immune responses against microbial pathogens. Both internal image and noninternal image anti‐idiotypic (anti‐Id) antibodies have been shown to trigger antigen (Ag)‐specific immune responses. Therefore, mechanisms of anti‐Id vaccination appear to go beyond structural mimicry of Ag, but remain undefined. Using the neurotropic murine coronavirus animal model, we have previously shown that a polyclonal noninternal image anti‐Id (Ab2) could vaccinate BALB/c mice. To characterize its mode of action, we have examined the immune modulating capability of this Ab2 in vivo in strains of mice with different H‐2 haplotypes. Even though only internal image anti‐Id are expected to induce non‐genetically restricted immunity, this noninternal image Ab2 induced protective immunity in four of eight genetically different strains of mice susceptible to coronavirus infection. These were BALB/c (H‐2d), DBA/1 (H‐2d), DBA/1 (H‐2q), and SWR (H‐2q) mice. Protection was generally correlated with the induction of specific antiviral Ab (Ab3) that showed biological properties, such as virus neutralization in vitro, similar to the initial Ab1. To evaluate the genetic implication of the H‐2 haplotypes in protection, congenic mice were also tested. Vaccination profiles suggest that cooperation between background gene(s) of the BALB/c mouse with H‐2d and H‐2q loci is necessary for an optimal protective immune response, although the main genetic element(s) regulating the antiviral response to Ab2 inoculation appeared to be located outside the major histocompatibility complex. These results are consistent with the ability of Ab2 to induce protective antiviral antibodies in genetically different animals by biological mimicry.
Interferon‐γ rescues HLA class Ia cell surface expression in term villous trophoblast cells by inducing synthesis of TAP proteins
Authors: Rodriguez Anne‐Marie , Mallet Valérie , Lenfant Françoise , Arnaud Jacques , Girr Maryse , Urlinger Stéphanie , Bensussan Armand , Le Bouteiller Philippe 
Published: March 2007

AbstractHuman placental trophoblast cells that constitute the materno‐fetal interface during pregnancy escape maternal alloimmune attack. The different trophoblast cell subpopulations have developed efficient regulatory mechanisms to prevent expression of β2‐microglobulin‐associated HLA class Ia molecules at their cell surface. We previously reported the presence of HLA class Ia messages in villous cytotrophoblast cells and in the syncytiotrophoblast differentiated in vitro purified from term placenta. In this study, we found that these transcripts are translated in heavy chain proteins that are endoglycosidase H sensitive and thus retained in the endoplasmic reticulum or cis‐Golgi. Moreover, these class Ia heavy chains can be co‐immunoprecipitated with the chaperone protein calnexin resident in the endoplasmic reticulum. When these trophoblast cells are treated with interferon (IFN)‐γ, part of the class Ia heavy chains become endoglycosidase H resistant, demonstrating that they have left the endoplasmic reticulum. Furthermore, after such a treatment, these heavy chains are detectable at the cell surface of these trophoblast cells, as assessed by two‐color flow cytometry analysis and immunoprecipitation of cell surface biotinylated proteins using the W6/32 anti‐HLA class I monoclonal antibody (mAb). IFN‐γ treatment induces a significant enhancement of the transcription of transporters associated with antigen processing (TAP1 and TAP2) rather than an increase of HLA class I or β2‐microglobulin messages. Finally, we demonstrate that an anti‐TAP1 mAb coimmunoprecipitates TAP1 proteins and HLA class Ia heavy chains in these IFN‐γ‐treated trophoblast cells. Thus, the constitutive absence of HLA class Ia cell surface expression in term villous cytotrophoblast and syncytiotrophoblast is likely to be due to a lack of transporter proteins that participate in the proper assembly of these molecules in the endoplasmic reticulum. Such a defect can be modified upon IFN‐γ treatment.
Antigen presentation by interferon‐γ‐treated thyroid follicular cells inhibits interleukin‐2 (IL‐2) and supports IL‐4 production by B7‐dependent human T cells
Authors: Lombardi Giovanna , Arnold Kate , Uren Julia , Marelli‐Berg Federica , Hargreaves Roseanna , Imami Nesrina , Weetman Anthony , Lechler Robert 
Published: March 2007

AbstractThe consequence of recognition of antigen on antigen‐presenting cells that are induced to express major histocompatibility complex (MHC) class II molecules following an inflammatory process is still not clear. In this study, we have investigated the outcome of antigen presentation by epithelial cells and we have used as a model thyroid follicular cells (TFC) that are known to express MHC class II molecules in autoimmune thyroid diseases and acquire the capacity to present autoantigens to T cells infiltrating the thyroid gland. The result show that MHC class II‐expressing TFC were unable to stimulate a primary T cell alloresponse, using CD4+ T cells from three HLA‐mismatched responders. Phenotypic analysis showed that TFC, after incubation with interferon‐γ, do not express the co‐stimulatory molecules B7‐1 (CD80) and ‐2 (CD86). Addition of murine DAP.3 cells expressing human B7‐1 (DAP.3‐B7) to cultures containing peripheral blood CD4+ T cells and DR1‐expressing TFC led to a proliferative response, suggesting that the failure of TFC to stimulate a primary alloresponse was due to a lack of co‐stimulation. Similarly, HLA‐DR‐restricted, influenza‐specific T cell clones dependent on B7 for co‐stimulation did not respond to peptide presented by TFC; again the lack of response could be overcome by co‐culture of TFC with DAP.3‐B7. Furthermore, recognition of antigen on TFC inhibited interleukin‐2 (IL‐2) production in the B7‐dependent T cells. In contrast, in T helper type 0 (Th0) T cells, IL‐4 release was not affected by TFC presentation. In addition, antigen presentation by TFC favored IL‐4 production relative to IL‐2 production by B7‐indpendent Th0 clones. These results suggest that antigen presentation by MHC class II+ TFC may induce tolerance in autoreactive Th1 cells but may simultaneously favors a Th2 response in uncommitted T cells, and thereby support autoantibody production.
The cytoplasmic domain of rat NKR‐P1 receptor interacts with the N‐terminal domain of p56lck via cysteine residues
Authors: Campbell Kerry S. , Giorda Roberto 
Published: March 2007

AbstractNKR‐P1 is a type II transmembrane protein which acts as an activation receptor on natural killer (NK) cells. The cytoplasmic domains of the CD4, CD8 and 4‐1BB receptors contain the sequence Cys‐X‐Cys‐Pro which is directly involved in coupling to another pair of cysteines in the N‐terminal domain of the src family tyrosine kinase p56lck. The cytoplasmic domain of NKR‐P1 in rodents also contains the Cys‐X‐Cys‐Pro sequence, but the capacity of the receptor to bind p56lck is presently unknown. We tested for direct coupling between these proteins using both protein biochemistry and the yeast two‐hybrid technique. Immunoprecipitation studies showed that p56lck can be co‐immunoprecipitated with NKR‐P1 from a rat NK tumor cell line. In addition, the cytoplasmic domain of NKR‐P1 interacted with the N‐terminal domain of p56lck in yeast as assessed by reporter gene activation. Integrity of the cysteine pairs in both proteins was critical in mediating the interaction. The experiments suggest that the association of p56lck with NKR‐P1 is somewhat weaker than the p56lck association with CD8α, but of much lower avidity than between CD4 and p56lck. This could reflect a higher activation threshold for the NKR‐P1 and CD8 receptors, which are involved in cytolytic responses, compared to CD4 which is involved in T cell helper function.
Cyclophosphamide‐induced blood and tissue eosinophilia in contact sensitivity: Mechanism of hapten‐induced eosinophil recruitment into the skin
Authors: Satoh Takahiro , Chen Qui‐Ji , Sasaki Go , Yokozeki Hiroo , Katayama Ichiro , Nishioka Kiyoshi 
Published: March 2007

AbstractThe mechanism leading to selective production and accumulation of eosinophils in certain allergic skin diseases is unknown. Cyclophosphamide treatment (150 mg/kg) of BALB/c mice 48 h before sensitization with picryl chloride (PCI) resulted in striking blood and tissue eosinophilia, maximal at 13 days. Blood eosinophilia was not induced by the sensitization with oxazolone and 2, 4‐dinitrofluorobenzene. Challenge with 1% PCI, but not croton oil caused preferential eosinophil accumulation into the dermis, which was associated with the enhanced expression of vascular cell adhesion molecule 1 (VCAM‐1) on endothelial cells. Intraveneous administration of anti‐VCAM‐1 monoclonal antibody abrogated eosinophil infiltration. In this murine model, we examined the role of several cytokines, including chemokines in inducing selective tissue eosinophilia in vivo. Local administration of antibodies against interleukin (IL)‐1β, IL‐4, tumor necrosis factor (TNF)‐α, and RANTES, but not against IL‐5 before challenge inhibited hapten‐induced eosinophil recruitment. Intradermal injection of recombinant (r)IL‐1β, rIL‐4, rTNF‐α, rRANTES, and rMIP‐1α induced marked eosinophil accumulation. Nonetheless, intradermal rIL‐5 was not a chemoattractant for eosinophils in vivo. Our findings suggest that IL‐1β, IL‐4, TNF‐α, and RANTES contribute to the selective accumulation of eosinophils in contact sensitivity reaction. Although circulating IL‐5 can activate eosinophils and prolong their survival, locally secreted IL‐5 is not crucial for inducing eosinophil recruitment into the skin.