bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: Protein Kinase Cβ Expression Is Critical for Export of IL-2 from T Cells
Authors: Long Aideen , Kelleher Dermot , Lynch Sara , Volkov Yuri 
Published: April 2014

Abstract
Protein kinase C (PKC) plays an integral part in T cell activation and IL-2 secretion. We investigated the role of a particular PKC isoform, PKCβ, in IL-2 production and secretion. The T cell lymphoma line HuT 78 secretes IL-2 in response to the phorbol ester PMA. A PKCβ-deficient clone of HuT 78, K-4, did not secrete IL-2 in response to PMA stimulation. As assessed by RT-PCR, K-4 expressed mRNA for IL-2 following PMA activation, and intracellular IL-2 protein was detected by immunofluorescence. An enhanced green fluorescent protein-linked PKCβ construct was microinjected into K-4 cells, which were then stimulated with PMA; those cells that expressed PKCβ could secrete IL-2, as determined by an in situ immunofluorescent assay. This study demonstrates that PKCβ is not necessary for transcription of the IL-2 gene or translation of mRNA to protein, but that expression of this PKC isoform is critical to the export of IL-2 molecules from T cells.
Antigen Presentation by Liver Cells Controls Intrahepatic T Cell Trapping, Whereas Bone Marrow-Derived Cells Preferentially Promote Intrahepatic T Cell Apoptosis
Authors: Mehal Wajahat Z. , Azzaroli Francesco , Crispe I. Nicholas 
Published: April 2014

AbstractSystemic activation and proliferation of CD8+ T cells result in T cell accumulation in the liver, associated with T cell apoptosis and liver injury. However, the role of Ag and APC in such accumulation is not clear. Bone marrow chimeras were constructed to allow Ag presentation in all tissues or alternatively to restrict presentation to either bone marrow-derived or non-bone marrow-derived cells. OVA-specific CD8+ T cells were introduced by adoptive transfer and then activated using peptide, which resulted in clonal expansion followed by deletion. Ag presentation by liver non-bone marrow-derived cells was responsible for most of the accumulation of activated CD8+ T cells. In contrast, Ag presentation by bone marrow-derived cells resulted in less accumulation of T cells in the liver, but a higher frequency of apoptotic cells within the intrahepatic T cell population. In unmodified TCR-transgenic mice, Ag-induced T cell deletion and intrahepatic accumulation of CD8+ T cells result in hepatocyte damage, with the release of aminotransaminases. Our experiments show that such liver injury may occur in the absence of Ag presentation by the hepatocytes themselves, arguing for an indirect mechanism of liver damage.
B Cell Receptor Cross-Linking Triggers a Caspase-8- Dependent Apoptotic Pathway That Is Independent of the Death Effector Domain of Fas-Associated Death Domain Protein
Authors: Besnault Laurence , Schrantz Nicolas , Auffredou Marie Thérèse , Leca Gérald , Bourgeade Marie Françoise , Vazquez Aimé 
Published: April 2014

AbstractWe have previously reported that B cell receptors, depending on the degree to which they are cross-linked, can promote apoptosis in various human B cell types. In this study, we show that B cell receptors can trigger two apoptotic pathways according to cross-linking and that these pathways control mitochondrial activation in human Burkitt’s lymphoma cells. Whereas soluble anti-μ Ab triggers caspase-independent mitochondrial activation, cross-linked anti-μ Ab induces an apoptotic response associated with a caspase-dependent loss of mitochondrial transmembrane potential. This B cell receptor-mediated caspase-dependent mitochondrial activation is associated with caspase-8 activation. We show here that caspase-8 inhibitors strongly decrease cross-linking-dependent B cell receptor-mediated apoptosis in Burkitt’s lymphoma BL41 cells. These inhibitors act upstream from the mitochondria as they prevented the loss of mitochondrial membrane potential observed in B cell receptor-treated BL41 cells. Caspase-8 activation in these cells was also evident from the detection of cleaved fragments of caspase-8 and the cleavage of specific substrates, including Bid. Our data show that cross-linked B cell receptors induced an apoptotic pathway involving sequential caspase-8 activation, loss of mitochondrial membrane potential, and the activation of caspase-9 and caspase-3. Cells expressing a dominant negative mutant of Fas-associated death domain protein were sensitive to cross-linked B cell receptor-induced caspase-8 activation and apoptosis; therefore, this caspase-8 activation was independent of the death effector domain of Fas-associated death domain protein.
The Dendritic Cell Populations of Mouse Lymph Nodes
Authors: Henri Sandrine , Vremec David , Kamath Arun , Waithman Jason , Williams Stuart , Benoist Christophe , Burnham Kim , Saeland Sem , Handman Emanuela , Shortman Ken 
Published: April 2014

AbstractThe dendritic cells (DC) of mouse lymph nodes (LN) were isolated, analyzed for surface markers, and compared with those of spleen. Low to moderate staining of LN DC for CD4 and low staining for CD8 was shown to be attributable to pickup of these markers from T cells. Excluding this artifact, five LN DC subsets could be delineated. They included the three populations found in spleen (CD4+8−DEC-205−, CD4−8−DEC-205−, CD4−8+DEC-205+), although the CD4-expressing DC were of low incidence. LN DC included two additional populations, characterized by relatively low expression of CD8 but moderate or high expression of DEC-205. Both appeared among the DC migrating out of skin into LN, but only one was restricted to skin-draining LN and was identified as the mature form of epidermal Langerhans cells (LC). The putative LC-derived DC displayed the following properties: large size; high levels of class II MHC, which persisted to some extent even in CIITA null mice; expression of very high levels of DEC-205 and of CD40; expression of many myeloid surface markers; and no expression of CD4 and only low to moderate expression of CD8. The putative LC-derived DC among skin emigrants and in LN also showed strong intracellular staining of langerin.
Unexpected Characteristics of the IFN-γ Reporters in Nontransformed T Cells
Authors: Zhu Hong , Yang Jianfei , Murphy Theresa L. , Ouyang Wenjun , Wagner Fred , Saparov Arman , Weaver Casey T. , Murphy Kenneth M. 
Published: April 2014

AbstractAnalysis of the IFN-γ promoter has primarily been conducted by transient expression of reporter constructs in transformed cells. However, the activity of cis elements may differ when expressed transiently compared with their activity within native chromatin. Furthermore, the transcription factors and signaling mechanisms in transformed cells may differ from those in normal T cells. To analyze IFN-γ promoter regulation in normal T cells, we developed a novel retroviral bottom-strand reporter system to allow the chromatin integration of promoter regions in primary developing T cells. As controls, both the IL-2 and IL-4 promoters were inducible in this system, with the IL-4 reporter having Th2-specific activity. Strikingly, the IFN-γ promoter exhibited constitutive activity in both Th1 and Th2 subsets, in contrast to the behavior of the endogenous IFN-γ gene, which is inducible only in Th1 cells. In mapping this activity, we found that the AP-1/GM-CSF site in the distal promoter element is the most critical element for the constitutive activity. Transgenic reporter lines for the IFN-γ promoter confirmed the constitutive behavior of the isolated IFN-γ promoter. This constitutive activity was resistant to inhibition by cyclosporin A and was independent of Stat4 and p38 mitogen-activated protein kinase. These results suggest that IFN-γ promoter regulation may require cis elements residing either downstream or &gt;3.4 kb upstream of the transcriptional start site, involving repression of constitutive activity.
Functional CD4 T Cells after Intercellular Molecular Transfer of OX40 Ligand
Authors: Baba Eishi , Takahashi Yoshiaki , Lichtenfeld Juliane , Tanaka Reiko , Yoshida Atsushi , Sugamura Kazuo , Yamamoto Naoki , Tanaka Yuetsu 
Published: April 2014

AbstractOX40/OX40 ligand (OX40L) proteins play critical roles in the T cell-B cell and T cell-dendritic cell interactions. Here we describe the intercellular transfer of OX40L molecules by a non-Ag specific manner. After 2-h coculture of activated CD4+ T cell (OX40L−, OX40+) with FLAG peptide-tagged OX40L (OX40L-flag) protein-expressing COS-1 cells, the OX40L-flag protein was detected on the cell surface of the CD4+ T cells by both anti-OX40L and anti-FLAG mAbs. The intercellular OX40L transfer was specifically abrogated by pretreatment of the COS-1 cells with anti-OX40L mAb, 5A8. The OX40L transfer to OX40-negative cells was also observed, indicating an OX40-independent pathway of OX40L transfer. HUVECs, allostimulated monocytes, and human T cell leukemia virus type I-infected T cells, which all express OX40L, can potentially act as the donor cells of OX40L. The entire molecule of OX40L was transferred and stabilized on the recipient cell membrane with discrete punctate formation. The transferred OX40L on normal CD4+ T cells was functionally active as they stimulated latent HIV-1-infected cells to produce viral proteins via OX40 signaling. Therefore, these findings suggest that the intercellular molecular transfer of functional OX40L may be involved in modifying the immune responses.
Oxidative Responses of Human and Murine Macrophages During Phagocytosis ofLeishmania chagasi
Authors: Gantt Kira R. , Goldman Todd L. , McCormick Michael L. , Miller Melissa A. , Jeronimo Selma M. B. , Nascimento Eliana T. , Britigan Bradley E. , Wilson Mary E. 
Published: April 2014

AbstractLeishmania chagasi, the cause of South American visceral leishmaniasis, must survive antimicrobial responses of host macrophages to establish infection. Macrophage oxidative responses have been shown to diminish in the presence of intracellular leishmania. However, using electron spin resonance we demonstrated that murine and human macrophages produce O2− during phagocytosis of opsonized promastigotes. Addition of the O2− scavenger 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl to cultures resulted in increased infection, suggesting that O2− enhances macrophage leishmanicidal activity. The importance of NO· produced by inducible NO synthase (iNOS) in controlling murine leishmaniasis is established, but its role in human macrophages has been debated. We detected NO· in supernatants from murine, but not human, macrophages infected with L. chagasi. Nonetheless, the iNOS inhibitor NG-monomethyl-l-arginine inhibited IFN-γ-mediated intracellular killing by both murine and human macrophages. According to RNase protection assay and immunohistochemistry, iNOS mRNA and protein were expressed at higher levels in bone marrow of patients with visceral leishmaniasis than in controls. The iNOS protein also increased upon infection of human macrophages with L. chagasi promastigotes in vitro in the presence of IFN-γ. These data suggest that O2− and NO· each contribute to intracellular killing of L. chagasi in human and murine macrophages.
A Dominant Role for Fcγ Receptors in Antibody-Dependent Corneal Inflammation
Authors: Hall Laurie R. , Diaconu Eugenia , Pearlman Eric 
Published: April 2014

AbstractAlthough production of specific Ab is a critical element of host defense, the presence of Ab in tissues leads to formation of immune complexes, which can trigger a type III Arthus reaction. Our studies on a mouse model of river blindness showed that Ab production is essential for recruitment of neutrophils and eosinophils to the cornea and for development of corneal opacification. In the current study, we determined the relative contribution of complement and FcγR interactions in triggering immune complex-mediated corneal disease. FcγR−/− mice, C3−/− mice, and immunocompetent control (B6/129Sj) mice were immunized s.c. and injected intrastromally with Onchocerca volvulus Ags. Slit lamp examination showed that control mice, C3−/− mice, and control mice injected with cobra venom factor developed pronounced corneal opacification, whereas corneas of FcγR−/− mice remained completely clear. Furthermore, recruitment of neutrophils and eosinophils to the corneal stroma was significantly impaired in FcγR−/− mice, but not in C3−/− mice or cobra venom factor-treated mice. We therefore conclude that FcγR-mediated cell activation, rather than complement activation, is the dominant pathway of immune complex disease in the cornea. These findings demonstrate a novel role for FcγR interactions in mediating ocular inflammation.
Regulation of Complement Classical Pathway by Association of C4b-Binding Protein to the Surfaces of SK-OV-3 and Caov-3 Ovarian Adenocarcinoma Cells
Authors: Holmberg Mikko T. , Blom Anna M. , Meri Seppo 
Published: April 2014

AbstractThe role of fluid-phase regulators of complement is to inhibit excessive complement activation and maintain homeostasis in blood. By binding to and inactivating complement components on cell surfaces, they can also protect autologous cells from complement-mediated cytotoxicity and phagocytosis. In this study, we wanted to find out whether C4b-binding protein (C4bp), a fluid-phase regulator of the classical complement pathway, could directly bind to cell surfaces in a functionally active form. After screening several malignant cell lines, we observed that the ovarian adenocarcinoma cell lines SK-OV-3, Caov-3, and SW626 were capable of binding C4bp. Binding tests with recombinant deletion mutants suggested that the primary binding site on C4bp is located on the α-chain complement control protein 4 domain. Functional tests showed that tumor cell-bound C4bp retained its cofactor activity for factor I-mediated inactivation of C4b, thus increasing the control of classical complement pathway activation on the surfaces of these cells. These results demonstrate a novel mechanism of complement regulation on cell surfaces, particularly on those of malignant ovarian tumor cells.
IL-12/IL-18-Dependent IFN-γ Release by Murine Dendritic Cells
Authors: Stober Detlef , Schirmbeck Reinhold , Reimann Jörg 
Published: April 2014

AbstractDendritic cells (DC) develop in GM-CSF-stimulated cultures from murine bone marrow progenitors in serum-free (or low serum) medium. CD11c+ myeloid DC from 7-day cultures stimulated with TNF-α, IFN-α, IFN-γ, or LPS up-regulated surface expression of CD40 and CD86 costimulator and MHC class II molecules, did not up-regulate the low “spontaneous” release of IL-18, and did not release IFN-γ. Stimulation of in vitro-generated DC with exogenous IL-12 and IL-18 (but not with IL-4 or LPS plus IL-18) induced IFN-γ expression and release in 15–20% of the DC (detectable by FACS analyses or ELISA). Endogenous IL-12 p70 produced by DC in response to ligation of CD40 stimulated IFN-γ release when exogenous IL-18 was supplied. In vivo-generated, splenic CD8α+ and CD8α− DC (from immunocompetent and immunodeficient H-2d and H-2b mice) cultured with IL-12 and IL-18 released IFN-γ. The presence of LPS during the stimulation of DC with IL-18 plus endogenous (CD40 ligation) or exogenous IL-12 did not affect their IFN-γ release. In contrast, splenic DC pretreated in vitro or in vivo by LPS strikingly down-regulated IFN-γ release in response to stimulation by IL-18 and (endogenous or exogenous) IL-12. Hence, DC are a source of early IFN-γ generated in response to a cascade of cytokine- and/or cell-derived signals that can be positively and negatively regulated.
Cutting Edge: The Mouse NK Cell-Associated Antigen Recognized by DX5 Moncoclonal Antibody is CD49b (α2 Integrin, Very Late Antigen-2)
Authors: Arase Hisashi , Saito Takashi , Phillips Joseph H. , Lanier Lewis L. 
Published: April 2014

Abstract
DX5 mAb is a useful reagent because it stains NK cells from all mouse strains examined. We have identified the molecule recognized by DX5 mAb by using a retrovirus-mediated expression cloning system. A 5-kb cDNA encoding a protein that is reactive with the DX5 mAb was isolated from a NK cell cDNA library, and this molecule was identical with CD49b (very late Ag-2, α2 integrin). The DX5 mAb reacted with transfectants expressing CD49b, and binding of DX5 to the NK cells and CD49b transfectants was blocked in the presence of other anti-CD49b mAbs. When NK1.1+ NK cells were cultured with IL-2, they progressively lost reactivity with DX5 mAb as a consequence of cellular proliferation. Cytotoxicity mediated by the DX5+ NK cells was dramatically higher as compared with DX5− NK cells. Therefore, DX5 mAb recognizes CD49b and can be used to define functionally distinct subsets of NK cells.
CD44 Is the Physiological Trigger of Fas Up-Regulation on Rheumatoid Synovial Cells
Authors: Fujii Koichi , Fujii Yuko , Hubscher Stefan , Tanaka Yoshiya 
Published: April 2014

AbstractCD44 is a ubiquitous molecule known as a hyaluronan receptor. However, the relevance of CD44 to inflammatory processes, for example, rheumatoid synovitis, remains unclear. In this study, we propose a novel function for CD44 using synovial cells from rheumatoid arthritis (RA) patients and demonstrated that CD44 cross-linking augmented Fas expression and subsequent Fas-mediated apoptosis of the cells: 1) cross-linking of CD44 on RA synovial cells markedly augmented Fas expression and its mRNA transcription; 2) engagement of CD44 up-regulated Fas on the cells within 3 h, much more than IL-1β and TNF-α did; 3) the Fas-mediated early apoptotic change of the cells was amplified by CD44 cross-linking; and 4) hyaluronan, especially when fragmented, also augmented Fas-mediated early apoptosis of the cells. Based on these findings, we postulate a new concept: that interaction of CD44 on RA synovial cells with hyaluronan fragments present in the surrounding extracellular matrix augments Fas expression as well as Fas-mediated apoptosis of synovial cells. This may lead to spontaneous growth arrest through Fas-Fas ligand pathway observed in synovial cells of RA synovitis in vivo.
Cross-Linking of EphB6 Resulting in Signal Transduction and Apoptosis in Jurkat Cells
Authors: Luo Hongyu , Wan Xiaochun , Wu Yulian , Wu Jiangping 
Published: April 2014

Abstract
Eph kinases are the largest family of receptor tyrosine kinases (RTK), and their ligands are cell surface molecules. The known functions of Eph kinases are mainly pattern formation in the CNS. Although several Eph kinases are expressed at high levels in hemopoietic cells and in the thymus, we have no knowledge of the functions of any Eph kinase in the immune system. In this study, we have demonstrated that an Eph kinase, EphB6, was expressed at high levels in Jurkat leukemic T cells. Co-cross-linking of EphB6 and CD3 led to an altered profile of lymphokine secretion along with proliferation inhibition of Jurkat cells. The cells subsequently underwent Fas-mediated apoptosis. Although EphB6 has no intrinsic kinase activity, its cross-linking triggered general protein tyrosine phosphorylation in Jurkat cells. EphB6 was found to associate with a number of molecules in the signaling pathways, notably Cbl. EphB6 cross-linking resulted in Cbl dephosphorylation and dissociation from Src homology 2 domain-containing tyrosine phosphatase-1 (SHP-1). Our results show that EphB6 has important functions in T cells, and it can transduce signals into the cells via proteins it associates with.
Development and Maintenance of a B220− Memory B Cell Compartment
Authors: Driver David J. , McHeyzer-Williams Louise J. , Cool Melinda , Stetson Daniel B. , McHeyzer-Williams Michael G. 
Published: April 2014

AbstractWe have recently demonstrated that a novel somatically mutated B220− memory B cell subset rapidly dominates the secondary immune response to (4-hydroxy-3-nitrophenyl) acetyl (NP). Upon adoptive transfer with Ag, B220+NP+ memory B cells produce large numbers of B220−NP+ B cells that can rapidly differentiate into plasma cells. Therefore, it is not clear whether the novel B220− memory compartment is a consequence of secondary Ag challenge or whether it develops as a stable memory subset after initial Ag challenge. In this study, we demonstrate the gradual emergence of B220−NP+ B cells in the spleen to maximal numbers 3 wk after initial Ag exposure. Like their B220+ counterparts, the B220− B cells initially appear unmutated at days 5–7; however, the majority rapidly accumulate affinity increasing mutations by days 9–14 of the primary immune response. More extensive cell surface phenotype (GL7−BLA-1−CD24−CD43+) argues strongly against germinal center localization and direct analysis in situ places a cohort of B220−CD11b+NP+ B cells in the red pulp of the spleen and not in the MZs. These data provide direct evidence for the development of B220− memory B cells as a unique cellular consequence of primary Ag exposure. The cellular dynamics and molecular attributes of these unique memory B cells suggest they are distinct cellular products of the germinal center reaction in the primary response and are maintained long-term in the spleen and bone marrow.
IL-12 Induction by a Th1-Inducing Adjuvant In Vivo: Dendritic Cell Subsets and Regulation by IL-10
Authors: Huang Li-Yun , Reis e Sousa Caetano , Itoh Yasushi , Inman John , Scott Dorothy E. 
Published: April 2014

AbstractIL-12 induction is critical for immune responses against many viruses and intracellular bacterial pathogens. Recent studies suggest that IL-12-secreting dendritic cells (DC) are potent Th1-inducing APC. However, controversy exists concerning the function of DC subsets. Murine studies have suggested that CD8+ DC preferentially induce Th1 responses, whereas CD8− DC induce Th2 development; in this model, different DC subsets prime different responses. Alternatively, the propensity of DC subsets to prime a Th1 response could depend upon the type of initial stimulus. We used a prototypic Th1-inducing adjuvant, heat-killed Brucella abortus (HKBA) to assess stimulation of DC subsets, relationship between Ag burden and IL-12 production, and down-regulation of DC subset IL-12 production by IL-10. In this study, we show that DC were sole producers of IL-12, although most HKBA uptake was by splenic macrophages and granulocytes. More CD8− than CD8+ DC produced IL-12 after HKBA challenge, whereas only CD8+ DC produced IL-12 after injection of another Th1-promoting microbial substance, soluble Toxoplasma gondii Ags. Studies in IL-10-deficient mice revealed that IL-10 down-regulates frequency and duration of IL-12 production by both DC subsets. In the absence of IL-10, IL-12 expression is enabled in CD11clow cells, but not in macrophages or granulocytes. These findings support the concept of DC as the major IL-12 producers in spleens, but challenge the notion that CD8+ and CD8− DC are destined to selectively induce Th1 or Th2 responses, respectively. Thus, the nature of the stimulating substance is important in determining which DC subsets are activated to produce IL-12.
Both TCRα and TCRδ Chain Diversity Are Regulated During Thymic Ontogeny
Authors: Gallagher Maighréad , Obeïd Patricia , Marche Patrice N. , Jouvin-Marche Evelyne 
Published: April 2014

Abstract
TCRα and TCRδ chains are coded by a common genetic locus using a single set of V gene segments (ADV segments). This article addresses the question of regulation of the use of the ADV segments by the TCRα and TCRδ chains. Using both qualitative and quantitative analyses we have studied the use of 23 ADV gene families as part of TCRα and TCRδ transcripts. A number of previously undetected rearrangement and transcription events are described, indicating that the intrathymic TCRδ repertoire is much more diverse than previously supposed. Repertoire analysis at several developmental time points allowed the description of regulated waves of ADV gene use, not only for TCRδ chains, but also for TCRα chains, during thymic ontogeny. Control of these waves appears to be linked directly to the ADV segments and their local chromatin environment, which may change over the course of T cell differentiation.