bluuebunny/crossref_metadata_2025_split huggingface dataset:
T cell receptor‐induced Fas ligand expression in cytotoxic T lymphocyte clones is blocked by protein tyrosine kinase inhibitors and cyclosporin A
Authors: Anel Alberto , Buferne Michel , Boyer Claude , Schmitt‐Verhulst Anne‐Marie , Golstein Pierre 
Published: March 2007

AbstractFas/APO‐1 is a member of the tumor necrosis factor receptor family of proteins, that induces apoptosis when cross‐linked with monoclonal antibody (mAb) or with its physiological ligand. Recently, both a perforin‐based and a Fas‐based mechanism have been proposed to account for T cell‐mediated cytotoxicity. In the present study we used a murine CD8+ cytotoxic T lymphocyte (CTL) clone (KB5.C20) specific for H‐2Kb and a T cell receptor (TcR)‐negative variant of the same clone (2005−D4) to test (i) whether the same cell can exert both cytotoxic effector mechanisms and (ii) the role of TcR engagement in the induction of Fas‐based cytotoxicity. We demonstrate that both the TcR+ and TcR− clones were able to express the Fas ligand after stimulation with phorbol 12‐myristate 13‐acetate (PMA)/ionomycin, and that TcR engagement of the KB5.C20 clone by means of antigen‐bearing cells or of its anticlonotypic mAb (Désiré‐1), which leads to Ca2+‐dependent, presumably perforin‐based, cytotoxicity, was also able to induce Fas‐based cytotoxicity. In addition, using inhibitors we investigated the signal transduction pathway(s) involved in the induction of Fas‐based cytotoxicity and expression of the Fas ligand mRNA in the CTL clones. The involvement of src‐like protein tyrosine kinases (PTK) in Fas ligand induction through TcR engagement, was strongly suggested by inhibition with the src‐like PTK inhibitor herbimycin A. Inhibition of Fas ligand induction by genistein, a more general TPK inhibitor, even upon stimulation by PMA plus ionomycin, suggested the possible involvement of PTK activities downstream of protein kinase C (PKC) in Fas ligand induction in CTL. Finally, the implication of the Ca2+/calmodulin‐dependent protein phosphatase calcineurin in Fas ligand induction was demonstrated by the partial inhibition of Fas ligand induction with cyclosporin A. Thus, in CTL clones, Fas ligand expression is inducible by TcR engagement through a pathway similar to that involved in expression of some lymphokine genes.
Triggering of human natural killer cells through CD16 induces tyrosine phosphorylation of the p72syk kinase
Authors: Ståhls Anders , Liwszyc Guillermo Eli , Couture Clément , Mustelin Tomas , Andersson Leif C. 
Published: March 2007

AbstractActivation of protein tyrosine kinases (PTK) is an initial and obligatory event for the triggering of human natural killer (NK) cells to cytotoxicity. Of the different PTK detected in NK cells, only p56lck has previously been shown to participate in NK cell activation. Here we present evidence that another PTK, p72syk, is involved in activation of NK cells. Stimulation with a monoclonal antibody to the FcγRIII receptor (CD16) induced an increased tyrosine phosphorylation of p72syk. This phosphorylation correlated with an increased tyrosine kinase activity of p72syk towards a synthetic peptide substrate. A severalfold increase in the catalytic activity of p72syk was also seen after treatment of NK cells with an inhibitor of phosphotyrosine phosphatases, pervanadate. We conclude that triggering of the cytotoxic response in NK cells is associated with activation of p72syk.
Dichotomy between the T and the B cell epitopes of the synthetic polypeptide (T,G)‐A–L
Authors: Zisman Einat , Sela Michael , Ben‐Nun Avraham , Mozes Edna 
Published: March 2007

AbstractStudies with the well‐characterized, synthetic, random‐multichain polypeptide poly(LTyr, LGlu)‐poly(DLAla)–poly(LLys) (T,G)‐A–L), led to the discovery of determinant‐specific genetic control of the immune response, as well as to other immunological phenomena. Moreover, the tetrapeptide TyrTyrGluGlu built on the same backbone (“T‐T‐G‐G)‐A–L”) was found to represent its major B cell epitope. We have recently shown that for interaction with major histocompatibility complex class II molecules and stimulation of T cells, (T, G)‐A–L requires proteolytic processing and the resulting T cell epitopes are close to the N termini of the branched polymer's side chains. Thus, we were interested to elucidate the major T cell epitope of (T, G)‐A–L, by using the ordered polypeptides (T‐T‐G‐G)‐A–L and (T‐G‐T‐G)‐A–L, in which only the two internal amino acids of the tetrapeptide attached to the side chains are switched. We established T cell lines to these antigens, and found that the ordered analog (T‐T‐G‐G)‐A–L, which was defined as the B cell epitope of (T,G)‐A–L, did not represent its T cell epitope, whereas (T‐G‐T‐G)‐A–L, to which only a minor anti‐(T,G)‐A–L Ab response was directed, was found to be its major T cell epitope. In addition, there was no cross‐reaction between (T‐G‐T‐G)‐A–L and (T‐T‐G‐G)‐A–L at the T cell level, similar to the lack of cross‐reaction of their antibodies. Analysis of the repertoire of the T cell receptors used by these lines revealed that the (T,G)‐A–L and the (T‐T‐G‐G)‐A–I specific T cell lines were not restricted in their Vα and Vβ TCR usage, whereas the (T‐G‐T‐G)‐A–L‐specific line was restricted by both Vα and Vβ T cell receptor gene products. This difference might be due to the thymus‐independent characteristics previously described for the latter antigen.
CD2‐CD48 interaction prevents apoptosis in murine B lymphocytes by up‐regulating bcl‐2 expression
Authors: Genaro Ana Maria , Gonzalo José Angel , Bosca Lisardo , Martinez‐A. Carlos 
Published: March 2007

AbstractAntigen receptor engagement initiates clonal expansion and antibody secretion in B lymphocytes in response to foreign antigens. However, binding of self antigen to antigen receptors targets self‐reactive B cell clones for elimination or inactivation. The antigen‐triggered biochemical events and the eventual response of the cells are dependent on the simultaneous occupancy of co‐stimulatory receptors. CD2 is an intercellular adhesion molecule implicated in cell activation and expressed in human T and natural killer cells as well as in mouse B lymphocytes. Mouse B cells specific for allogeneic major histocompatibility complex (MHC) class I initiate a suicide program that leads to DNA fragmentation and cell death when confronted with soluble MHC class I while undergoing clonal expansion when the antigen is present on mitomycin C‐treated cells. Here we show that occupancy of CD2 in mouse B cells by the presence of either monoclonal antibody (mAb) specific for CD2, or soluble recombinant mouse CD48, its natural ligand in mouse, prevents the induction of apoptosis. Furthermore, the in vitro activation by mitomycin C‐treated allogeneic cells, is abrogated in the presence of anti‐CD48 mAb (OX78). These results indicate that a CD2‐CD48 interaction is involved in the control of B cell activation.
Modulation of cytokine expression in mouse dendritic cell clones
Authors: Granucci Francesca , Girolomoni Giampiero , Lutz Manfred B. , Foti Maria , Marconi Giulia , Gnocchi Paola , Nolli Luisa , Ricciardi‐Castagnoli Paola 
Published: March 2007

AbstractDendritic cells (DC) play an essential role in the induction of primary immune responses; however, very little information is available on cytokine production by DC. Here we determined the cytokine gene expression profile of two immortalized DC clones, CB1 and D2SC/1, both generated from mouse spleen but differing in their activation requirements. Among the cytokines tested, only transforming growth factor‐β1 was transcribed constitutively, but its production was detected only in D2SC/1 cells after treatment with granulocyte/macrophage colony‐stimulating factor (GM‐CSF). GM‐CSF also promoted transcription and synthesis of interleukin (IL)‐1β in CB1 cells that need pretreatment with GM‐CSF to present major histocompatibility complex class II‐restricted antigens efficiently in vitro. Lipopolysaccharide (LPS) up‐regulated gene expression and induced release of tumor necrosis factor‐α in both DC clones. In addition, LPS induced transcription of IL‐1α and both gene expression and synthesis of IL‐1β in D2SC/1 cells. Interferon‐γ was ineffective in inducing cytokine gene expression, although it augmented the antigen‐presentation capacity of DC. IL‐4, IL‐10 and IL‐12 mRNA were not induced by any of the tested stimuli. The results suggest that DC have a limited cytokine gene expression pattern compared to macrophages and are heterogenous in some functional properties.
The human natural killer cell receptor for major histocompatibility complex class I molecules. Surface modulation of p58 molecules and their linkage to CD3 ζ chain, FcϵRI γ chain and the p56lck kinase
Authors: Bottino Cristina , Vitale Massimo , Olcese Lucia , Sivori Simona , Morelli Luigia , Augugliaro Raffaella , Ciccone Ermanno , Moretta Lorenzo , Moretta Alessandro 
Published: March 2007

AbstractThe natural killer cell (NK)‐specific p58 surface molecules, recognized by the GL183 and EB6 monoclonal antibodies (mAb), have been shown to represent the putative NK receptor for HLA‐C molecules. The interaction between p58 receptors and HLA‐C results in inhibition of the NK‐mediated target cell lysis. In this study, GL183−EB6+ clones (Cw4‐specific), after mAb‐induced surface modulation of EB6 molecules, acquired the ability to lyse the Cw4− C1R cells. In NK clones co‐expressing both GL183 and EB6 molecules and unable to kill Cw3‐protected target cells, the mAb‐induced modulation of EB6 molecules resulted both in selective co‐modulation of GL183 molecules and in the lysis of Cw3‐transfected P815 murine cells. In line with the co‐modulation experiments we also show that the GL183 and EB6 molecules can be co‐immunoprecipitated from GL183+/EB6+ clones after cell lysis in the presence of digitonin. The p58 receptor also revealed an association with molecules belonging to the ζ family (i.e. CD3 ζ and FcϵRI γ chains). Two‐dimensional diagonal gel analysis of the p58 complex immunoprecipitated from polyclonally activated p58+ NK cells indicated a preferential association with CD3 ζ chains either in the form of covalently linked ζ‐γ homodimers or in the form of ζ‐γ heterodimers, while γ‐γ homodimers were detectable in low amounts. However, p58+ clones displaying a unique association with γ‐γ homodimers could also be isolated. Probing the immunoprecipitated p58 complex with anti‐p56lck antibody also revealed an association with this member of the src family. In addition, mAb‐mediated signaling of NK clones via p58 molecules induced increments of p58/p56lck association. However, under the same experimental conditions that induced optimal in vivo tyrosine phosphorylation of the CD16‐associated CD3 ζ chains, no tyrosine phosphorylation was detected in the p58‐associated CD3 ζ, chains. In these in vivo experiments neither anti‐CD16 nor anti‐p58 mAb could induce tyrosine phosphorylation of the γ chains. Finally, the anti‐p58‐mediated inhibition of the NK cell triggering via CD16 molecules was not accompained by a down‐regulation of the tyrosine phosphorylation of the CD16‐associated CD3 ζ chains.
Structure of HLA‐B27‐specific T cell epitopes. Antigen presentation in B2703 is limited mostly to a subset of the antigenic determinants on B2705
Authors: Villadangos José A. , Galocha Begoña , García‐Hoyo Rosa , López Daniel , García Fernando , de Castro José A. Łópez 
Published: March 2007

AbstractThe structure of HLA‐B27‐specific epitopes recognized by anti‐B*2705 and anti‐B*2703 cytotoxic T lymphocytes (CTL) from three unrelated donors was examined with site‐specific mutants at various side‐chain pockets in the antigen‐binding site. The effect of any given mutation on allorecognition correlated strongly with its predictable effect on peptide binding. Acidic charges in the C/F pocket of HLA‐B27, which binds C‐terminal peptide residues, strongly modulated allorecognition. Anti‐B*2705 CTL from different donors were differently affected by some mutations, indicating individual differences in the structure of epitopes recognized by alloreactive CTL from each donor. Most anti‐B*2703 CTL recognized a subset of epitopes that were also present on B*2705, but differed from the bulk of allospecific epitopes on this subtype in their smaller dependence on pocket A structure, where the difference between these subtypes is located, and in their greater dependence on Glu45, in the B pocket. The structure of the very few epitopes on B*2703 not shared by B*2705 was quite different from that of the much more predominant cross‐reactive epitopes. The results strongly suggest that B*2703 is antigenically defective as compared with B*2705 and that this is due to the fact that the repertoire of peptides presented by B*2703 consists mainly of a subset of the B*2705‐bound peptides which do not critically require the canonic binding of the peptidic N‐terminus to a B*2705‐like A pocket, because they are sufficiently stabilized by other contacts through the peptide binding site.
Segregation of APO‐1/Fas antigen‐ and tumor necrosis factor receptor‐mediated apoptosis
Authors: Grell Matthias , Krammer Peter H. , Scheurich Peter 
Published: March 2007

AbstractThe cytokine tumor necrosis factor (TNF) and the APO‐1/Fas ligand represent typical inducers of apoptosis, i.e. programmed cell death. A limited sequence homology between the TNF receptor TR60 (p55) and the APO‐1/Fas (CD95) antigen in their intracellular domains suggests overlapping signaling pathways. The TNF‐sensitive cell line KYM‐1, which expresses high numbers of both TNF receptors and the APO‐1/Fas antigen, is highly sensitive towards triggering of apoptosis by each of the TNF receptors, but resistant to APO‐1/Fas stimulation. The opposite response pattern was obtained using the B lymphoid line SKW 6.4, which also co‐expresses all three cell surface molecules. Furthermore, no co‐modulation of APO‐1/Fas by down‐regulation of cell surface expressed TR60 and/or TR80 receptors, and vice versa, was found. These data argue against a physical interaction of TNF receptors with APO‐1/Fas and, in addition, demonstrate cell specific control of induction of apoptosis and usage of distinct signaling pathways by these receptor molecules.
Apoptotic elimination of Vβ8.2+ cells from the central nervous system during recovery from experimental autoimmune encephalomyelitis induced by the passive transfer of Vβ8.2+ encephalitogenic T cells
Authors: Tabi Zsuzsanna , McCombe Pamela A. , Pender Michael P. 
Published: March 2007

AbstractA CD4+Vβ8.2+ T cell clone specific for the peptide 72–89 of guinea pig myelin basic protein (GMBP) was used to induce acute experimental autoimmune encephalomyelitis (EAE) in Lewis rats. To assess apoptosis in inflammatory cells infiltrating the central nervous system (CNS), we extracted cells from the spinal cord, enriched them for T cells and performed flow‐cytometric analysis of their DNA stained with propidium iodide. The presence of apoptosis was confirmed by the demonstration of DNA fragmentation on gel electrophoresis. A gradual increase in the proportion of apoptotic cells was observed between 4 and 7 days after the transfer of the encephalitogenic T cells. The highest frequency of apoptotic cells (9.2 ± 1.2%) was observed 7 days after cell transfer, when clinical recovery commenced. Passive transfer of ovalbumin‐specific cells resulted in only a background level (0.8%) of apoptosis in the CNS. We conclude that the apoptotic process selectively eliminates autoreactive T cells from the CNS as: (a) there was a selective disappearance of disease‐relevant CD5+Vβ8.2+ cells from the CNS during the course of EAE; (b) there was a decrease in the frequency of CNS‐infiltrating T cells reactive to the GMBP 72–89 peptide during the course of EAE, and in a standard proliferation assay there was a loss of in vitro reactivity of CNS‐infiltrating cells to this peptide, but not to a non‐CNS antigen (ovalbumin); (c) simultaneous surface labeling and DNA analysis of CNS‐infiltrating cells revealed that the frequency of Vβ8.2+ cells was about sevenfold higher in the apoptotic T cell population than in the normal (non‐apoptotic) T cell population; and (d) we were unable to detect recirculation of the Vβ8.2+ cells to lymphoid organs after their frequency decreased in the CNS. The selective apoptotic elimination of autoreactive T cells from the target organ of this spontaneously resolving autoimmune disease may have implications for the understanding of the mechanism by which an autoimmune attack is terminated and for the design of therapeutic strategies to facilitate this process.
Recognition of apoptotic cells by human macrophages: inhibition by a monocyte/macrophage‐specific monoclonal antibody
Authors: Flora Pauline K. , Gregory Christopher D. 
Published: March 2007

AbstractCells undergoing death by apoptosis are rapidly engulfed by phagocytes in vivo, a highly efficient process which prevents leakage of potentially dangerous intracellular contents from dying cells to neighboring tissue. We have tested a panel of monoclonal antibodies (mAb) specifying a range of human monocyte/macrophage surface antigens for their capacity to inhibit the in vitro recognition of apoptotic cells by human peripheral blood monocyte‐derived macrophages. The results identify the antigen defined by the 61D3 mAb, a widely‐used marker of monocyte/macrophage lineage cells, as an important mediator of apoptotic cell recognition. In our system, apoptotic, but not viable, cells were recognized by the cultured macrophages and 61D3 was found to inhibit the recognition of all apoptotic cell types tested, including Ca2+ ionophore‐treated or growth factor‐depleted B and T lymphocyte lines, tonsillar germinal center B cells, irradiated peripheral blood lymphocytes and senescing neutrophils. Furthermore, the apoptotic cell recognition pathway specified by 61D3 could be distinguished from that involving the macrophage αvβ3 vitronectin receptor which has been shown previously to play an important role in the recognition of apoptotic cells. These results provide further evidence that the mechanisms underlying rapid clearance of apoptotic cells involve multiple phagocyte receptors.
Fas ligation triggers apoptosis in macrophages but not endothelial cells
Authors: Richardson Bruce C. , Lalwani Narendra D. , Johnson Kent J. , Marks Rory M. 
Published: March 2007

AbstractThe reticuloendothelial system includes macrophages and endothelial cells. These cells are produced and destroyed in vivo with a precision that implies the existence of homeostatic mechanisms. The stimuli for endothelial cell proliferation and monocyte production are becoming well characterized. However, the mechanisms involved in eliminating these cells are poorly understood. One mechanism involved in cellular elimination is apoptosis, which can be triggered in some cells by ligation of the Fas molecule. In this report we have investigated whether macrophages and endothelial cells express the Fas molecule, and whether Fas transmits an apoptosis‐inducing signal in these cells. We demonstrate that macrophages express Fas and readily undergo apoptosis when cultured with anti‐Fas. In contrast, while endothelial cells can express the Fas molecule, Fas ligation is insufficient to induce apoptosis. These results suggest differential regulation of Fas function among cells of the reticuloendothelial system, and imply different mechanisms of homeostasis.
Characterization of cytokine‐producing cells in mucosal effector sites: CD3+ T cells of Th1 and Th2 type in salivary gland‐associated tissues
Authors: Hiroi Takachika , Fujihashi Kohtaro , McGhee Jerry R. , Kiyono Hiroshi 
Published: March 2007

AbstractThe major purpose of this study was to elucidate Th1 [interferon (IFN)‐γ and interleukin (IL)‐2] and Th2 (IL‐4, IL‐5 and IL‐6) cytokine‐producing CD3+ T cells in salivary glands, which are the major mucosal effector tissues in the oral region. Thus, CD3+ T cells were isolated from salivary gland‐associated tissues (SGAT) which consist of the submandibular gland (SMG: ∼46%), the periglandular lymph node (PGLN: ∼ 72 %), and the cervical lymph node (CLN: ∼ 90%). When SMG CD3+ T cells were examined by Th1 and Th2 cytokine‐specific ELISPOT and reverse transcriptase‐polymerase chain reaction assay, high levels of both cytokine‐specific spot‐forming cells (SFC) and mRNA for IFN‐γ, and for IL‐5 and IL‐6 were noted as representative Th1 or Th2 cytokines, respectively. Following stimulation with concanavalin A (Con A), SMG CD3+ T cells expressed mRNA and produced lymphokines for an array of Th1 (IFN‐γ and IL‐2) and Th2 (IL‐4, IL‐5 and IL‐6) cytokines. In comparison to the SMG CD3+ T cells, PGLN and CLN contain lower numbers of IFN‐γ‐, IL‐5‐ and IL‐6‐producing T cells. When these two tissues were compared, PGLN CD3+ T cells contained higher numbers of cytokine‐secreting cells than CLN. Further, IL‐2 and IL‐4 SFC and mRNA were also noted in addition to IFN‐γ, IL‐5 and IL‐6 after Con A activation. These findings showed that CD3+ T cells in SGAT, especially the SMG, are programmed to produce IFN‐γ, and IL‐5 and IL‐6 as Th1 and Th2 cytokines, respectively in vivo, although these cells are capable of producing other Th1 and Th2 cytokines after receiving appropriate T cell activation signals.
Restricted use of T cell receptor V genes in endomysial infiltrates of patients with inflammatory myopathies
Authors: Lindberg Christopher , Oldfors Anders , Tarkowski Andrzej 
Published: March 2007

AbstractInclusion body myositis (IBM), polymyositis (PM) and dermatomyositis (DM) are diseases characterized clinically by progressive muscle weakness and histologically by T lymphocyte infiltrates in striated muscle. The pathogenetic role of these cells is proposed to be cell‐mediated cytotoxicity in PM and IBM, but the exact mechanisms of their action are poorly understood. Characterization of the variable regions of T cell receptors (TcR) on the infiltrating lymphocytes may be expected to provide insights into the mechanisms of local activation of the immune system in inflammatory myopathies. Immunohistochemical analysis using a panel of monoclonal antibodies specific for 11 Vα/β TcR was performed on cryosectioned muscle biopsy specimens from eight patients with IBM, eight with PM and three with DM. In addition, TcR expression was studied in inflammatory infiltrates in skin biopsies obtained from some of the IBM patients challenged locally with tuberculin. Flow cytometry was used to assess expression of TcR on peripheral blood lymphocytes. All the patients displayed a clear restriction of TcR usage, preferentially limited to Vα2 and Vβ3 TcR families in the endomysial, but not in perivascular infiltrates, even within the same muscle specimen. Such a restriction was not found in skin punch biopsies or PBL from the same subjects. Our results suggest that T cells extravasate non‐selectively to the skeletal muscle, but once there, only certain TcR families proliferate, presumably after encounter with a locally exposed superantigen.