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  • 1
    Online Resource
    Online Resource
    B7-1 and B7-2: Similar costimulatory ligands with different biochemical, oligomeric and signaling properties
    Elsevier BV ; 2006
    In:  Immunology Letters Vol. 104, No. 1-2 ( 2006-4), p. 70-75
    Details
    In: Immunology Letters, Elsevier BV, Vol. 104, No. 1-2 ( 2006-4), p. 70-75
    Type of Medium: Online Resource
    ISSN: 0165-2478
    URL: Article
    DOI: 10.1016/j.imlet.2005.11.019
    RVK:
    XA 10000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2006
    detail.hit.zdb_id: 2013171-9
    SSG: 12
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  • 2
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    Structural Basis of Inducible Costimulator Ligand Costimulatory Function: Determination of the Cell Surface Oligomeric State and Functional Mapping of the Receptor Binding Site of the Protein
    The American Association of Immunologists ; 2006
    In:  The Journal of Immunology Vol. 177, No. 6 ( 2006-09-15), p. 3920-3929
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 177, No. 6 ( 2006-09-15), p. 3920-3929
    Abstract: Inducible costimulator (ICOS) ligand (ICOSL), a B7-related transmembrane glycoprotein with extracellular IgV and IgC domains, binds to ICOS on activated T cells and delivers a positive costimulatory signal for optimal T cell function. Toward determining the structural features of ICOSL crucial for its costimulatory function, the present study shows that ICOSL displays a marked oligomerization potential, resembling more like B7-1 than B7-2. Use of ICOSL constructs lacking either the IgC or IgV domain demonstrates that receptor binding is mediated solely by the IgV domain but requires the IgC domain for maintaining the structural integrity of the protein. To map further the receptor recognition surface on ICOSL, a homology-based protein structure model of the ICOS:ICOSL complex was constructed. Based on predictions from the model, a series of mutations were generated targeting the potential receptor binding surface on ICOSL, and the mutants were tested for their biological function in terms of ICOS binding and T cell costimulation ability. The results provide experimental validation of the model and show that the receptor binding site on ICOSL is constituted chiefly by aromatic/hydrophobic residues. Critical ICOSL residues essential for ICOS binding map to the GFCC′C″ β-sheet face of the IgV domain and approximately overlap with the B7-1/B7-2 motif(s) that recognize CD28/CTLA-4. Altogether, similar structural features of ICOSL and B7 isoforms suggest a close evolutionary relationship between these costimulatory ligands, yet differences at the same time explain their unique specificity for the cognate binding partners, ICOS and CD28/CTLA-4, respectively.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.177.6.3920
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2006
    detail.hit.zdb_id: 1475085-5
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  • 3
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    Costimulatory pathways mediating T-dependent germinal center responses: distinct cellular requirements for CD40 and B7 costimulation
    The American Association of Immunologists ; 2016
    In:  The Journal of Immunology Vol. 196, No. 1_Supplement ( 2016-05-01), p. 55.25-55.25
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 196, No. 1_Supplement ( 2016-05-01), p. 55.25-55.25
    Abstract: T cell-dependent (TD) germinal center (GC) and antibody responses require coordinated interactions of T cells with B cells and antigen-presenting dendritic cells (DCs). Although B7 and CD40 costimulatory pathways are critical for these responses, a comprehensive analysis of cell type-specific pathways has been hindered by the absence of models for conditional expression of B7 or CD40. Here we report generation of conditional knockout mice for both B7 and CD40, and the use of these lines together with conditional MHC class II (MHCII) knockouts and bone marrow chimeric strategies, to analyze pathways involved in TD GC and antibody responses. Our results indicate that MHCII-restricted recognition of both DCs and B cells is necessary for generation of antigen-specific TFH cells, GC B cells, and antibody response. Notably, the requirements for expression of B7 and CD40 were distinct, with B7 expression required on DCs but not on B cells, while CD40 was required on B cells but not DCs for generation of TFH cells, antigen-specific GC B cells, and antigen-specific class-switched antibody responses. These findings identify requirements for cell and costimulatory interactions in TD GC and antibody responses and support a unique model in which major costimulatory pathways function through interaction of T cells with distinct cell populations.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.196.Supp.55.25
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2016
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  • 4
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    The pathway for MHCII-mediated presentation of endogenous proteins involves peptide transport to the endo-lysosomal compartment
    The Company of Biologists ; 2004
    In:  Journal of Cell Science Vol. 117, No. 18 ( 2004-08-15), p. 4219-4230
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 117, No. 18 ( 2004-08-15), p. 4219-4230
    Abstract: Antigen-presenting cells (APCs) are expected to present peptides from endocytosed proteins via major histocompatibility complex (MHC) class II (MHCII) molecules to T cells. However, a large proportion of peptides purified from MHCII molecules are derived from cytosolic self-proteins making the pathway of cytosolic peptide loading onto MHCII of critical relevance in the regulation of immune self-tolerance. We show that peptides derived from cytoplasmic proteins either introduced or expressed in the cytoplasm are first detectable as MHCII-peptide complexes in LAMP-1+ lysosomes, prior to their delivery to the cell surface. These peptide-MHC complexes are formed in a variety of APCs, including peritoneal macrophages, dendritic cells, and B cells, and are able to activate T cells. This process requires invariant chain (Ii)-dependent sorting of MHCII to the lysosome and the activity of the molecular chaperone H-2M. This pathway is independent of the ER resident peptide transporter complex TAP and does not take place by cross-presentation from neighbouring cells. In conjunction with our earlier results showing that these peptides are derived by cytosolic processing via the proteasome, these observations provide evidence for a ubiquitous route for peptide transport into the lysosome for the efficient presentation of endogenous and cytoplasmic proteins to CD4 T cells.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.01288
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2004
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Prohibitins and the cytoplasmic domain of CD86 are necessary to mediate signaling in B lymphocytes (109.8)
    The American Association of Immunologists ; 2011
    In:  The Journal of Immunology Vol. 186, No. 1_Supplement ( 2011-04-01), p. 109.8-109.8
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 186, No. 1_Supplement ( 2011-04-01), p. 109.8-109.8
    Abstract: CD86 engagement on a CD40L/IL-4-primed murine B cell activates signaling intermediates that lead to an increase in Oct-2 and mature IgG1 mRNA and protein expression, without affecting class switch recombination. The most proximal signaling intermediates identified thus far are Lyn and phospholipase Cγ2α/β, which are usually activated after recruitment and binding to phospho-tyrosine residues on receptors, but the cytoplasmic domain of CD86 lacks tyrosines. Using a proteomics-based identification approach, we show that the tyrosine-containing transmembrane adaptor proteins, prohibitin-1 (Phb1) and Phb2, bind to CD86. The basal association is low in resting cells, but increased after priming with CD40L/IL-4. The level of total Phb1/2 expression increased primarily via a CD40-dependent mechanism. Phb1 protein expression and binding to CD86 were consistently greater than that for Phb2 in CD40L/IL-4-primed B cells. The CD86-induced increase in Oct-2 and IgG1 was reduced when either Phb1/2 expression was silenced by shRNA or when the cytoplasmic domain of CD86 was truncated or mutated at the serine/threonine protein kinase C-phosphorylation sites. Truncation of the CD86 cytoplasmic domain did not affect the binding of Phb1/2 to CD86, or the level of T cell activation and class switch recombination. These findings suggested that Phb1/2 and the CD86 cytoplasmic domain are each necessary to mediate the CD86-induced signaling in B cells.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.186.Supp.109.8
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2011
    detail.hit.zdb_id: 1475085-5
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  • 6
    Online Resource
    Online Resource
    Prohibitins and the cytoplasmic domain of CD86 cooperate to mediate CD86 signaling in B lymphocytes (42.5)
    The American Association of Immunologists ; 2012
    In:  The Journal of Immunology Vol. 188, No. 1_Supplement ( 2012-05-01), p. 42.5-42.5
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 188, No. 1_Supplement ( 2012-05-01), p. 42.5-42.5
    Abstract: CD86 engagement on a CD40L/IL-4-primed murine B cell activates signaling intermediates that increase Oct-2 and IgG1 mRNA and protein expression, independent of class switch recombination. One of the most proximal intermediates identified is PLCγ2. Since the cytoplasmic domain of CD86 lacks tyrosine residues reported to bind PLCγ2, we used a proteomics-based identification approach to show that the tyrosine-containing transmembrane adaptor proteins, prohibitin-1 (Phb1) and prohibitin-2 (Phb2), bind to CD86. Although basal expression of Phb1/2 and association with CD86 was low in resting B cells, expression and association increased after CD40 engagement. The CD86-induced increase in Oct-2 and IgG1 was less when either Phb1/2 expression was reduced by shRNA or the cytoplasmic domain of CD86 was truncated or mutated at serine/threonine PKC-phosphorylation sites, but did not affect Phb1/2 binding to CD86. Furthermore, Phb1/2 reduction and CD86 truncation revealed that the CD86-induced phosphorylation of PLCγ2 required Phb1/2 alone; whereas, IκBα and NF-κB (p65) phosphorylation required both Phb1/2 and the CD86 cytoplasmic domain. Together, these findings suggest that Phb1/2 and the CD86 cytoplasmic domain cooperate to mediate CD86 signaling in a B cell to regulate IgG1 production and is the first evidence to define the molecular basis of membrane-proximal CD86 signal transduction in B cells.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.188.Supp.42.5
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2012
    detail.hit.zdb_id: 1475085-5
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  • 7
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    Dynamic equilibrium of B7-1 dimers and monomers is important for regulation of TCR/CD28 – mediated T cell activation (33.28)
    The American Association of Immunologists ; 2009
    In:  The Journal of Immunology Vol. 182, No. 1_Supplement ( 2009-04-01), p. 33.28-33.28
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 182, No. 1_Supplement ( 2009-04-01), p. 33.28-33.28
    Abstract: Under steady state conditions, B7-1 is present as a mixed population of non-covalent dimers and monomers on the cell surface. Here we have examined the physiological significance of this unique dimer-monomer equilibrium state of B7-1. We demonstrate that altering B7-1 to uniformly covalent dimeric state results in increased frequency of CD28 mediated T cell-APC conjugates. This augmented T cell-APC conjugate formation correlates with persistent concentration of signaling molecules, PKC-θ and lck, at the immunological synapse (IS) and with a higher calcium flux in T cells. In contrast, B7-1 acquisition by T cells, an event that occurs as a consequence of CD28 engagement with B7-1/B7-2, is highly reduced when B7-1 is present in covalently dimeric state. The ability of covalently dimeric and wild type B7-1 to costimulate antigen-specific T cell proliferation was also assessed. In contrast to the enhanced ability of dimeric B7-1 to support proximal T cell activation events, sensitivity to competitive inhibition by soluble CTLA-4:Ig indicated that the covalent dimeric form of B7-1 is in fact less efficient in costimulating T cell proliferation. These findings suggest a novel model in which optimal T cell costimulatory function of B7-1 requires CD28 engagement by B7-1 in a non-covalent dimeric state, followed by dissociation of these B7-1 dimers, facilitating downregulation of CD28 and internalization of B7-1.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.182.Supp.33.28
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2009
    detail.hit.zdb_id: 1475085-5
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  • 8
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    Pentoxifylline Functions As an Adjuvant In Vivo to Enhance T Cell Immune Responses by Inhibiting Activation-Induced Death
    The American Association of Immunologists ; 2002
    In:  The Journal of Immunology Vol. 169, No. 8 ( 2002-10-15), p. 4262-4272
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 169, No. 8 ( 2002-10-15), p. 4262-4272
    Abstract: Modalities for inducing long-lasting immune responses are essential components of vaccine design. Most currently available immunological adjuvants empirically used for this purpose cause some inflammation, limiting clinical acceptability. We show that pentoxifylline (PF), a phosphodiesterase (PDE) inhibitor in common clinical use, enhances long-term persistence of T cell responses, including protective responses to a bacterial immunogen, Salmonella typhimurium, via a cAMP-dependent protein kinase A-mediated effect on T cells if given to mice for a brief period during immunization. PF inhibits activation-mediated loss of superantigen-reactive CD4 as well as CD8 T cells in vivo without significantly affecting their activation, and inhibits activation-induced death and caspase induction in stimulated CD4 as well as CD8 T cells in vitro without preventing the induction of activation markers. Consistent with this ability to prevent activation-induced death in not only CD4 but also CD8 T cells, PF also enhances the persistence of CD8 T cell responses in vivo. Thus, specific inhibition of activation-induced T cell apoptosis transiently during immune priming is likely to enhance the persistence of CD4 and CD8 T cell responses to vaccination, and pharmacological modulators of the cAMP pathway already in clinical use can be used for this purpose as immunological adjuvants.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.169.8.4262
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2002
    detail.hit.zdb_id: 1475085-5
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  • 9
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    The dynamic equilibrium between dimeric and monomeric cell surface B7-1 regulates T cell activation and CD28 expression (88.1)
    The American Association of Immunologists ; 2007
    In:  The Journal of Immunology Vol. 178, No. 1_Supplement ( 2007-04-01), p. S138-S138
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 178, No. 1_Supplement ( 2007-04-01), p. S138-S138
    Abstract: Numerous studies have identified differences between B7-1:CD28/CTLA-4 and B7-2:CD28/CTLA-4 complexes that form at the immunological synapse. Our earlier studies have established that B7-1 is expressed as a mixture of predominant non-covalent dimers and monomers on the cell surface. In order to test the hypothesis that altering the nature of B7-1:CD28 complexes will have functional consequences for T cell activation, we generated a disulfide-linked covalent dimer of B7-1 (B7-1:Cys), as well as mutants of B7-1 (L58D and I68D) that exist as a monomer on the cell surface. We used modulation of cell surface CD28 to assess the outcome of binding of B7-1 mutants to CD28 as one measure of the dynamics of B7-1:CD28 interaction since earlier studies have shown that CD28 is transiently downregulated upon binding to WT B7-1. As expected, L58D and I68D mutants resulted in reduced T cell activation and reduced CD28 downregulation when compared to WT B7-1, potentially due to low avidity interaction between monomeric B7-1 and monovalent CD28. Surprisingly, B7-1:Cys also resulted in less T cell activation than WT B7-1. Moreover, B7-1:Cys also resulted in reduced downregulation of CD28. These data suggest a novel model in which optimal B7-1 function for CD28 downmodulation and T cell activation requires CD28 engagement by non-covalent B7-1 dimers, followed by dissociation of B7-1 to a monomeric state, potentially facilitating disengagement from CD28.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.178.Supp.88.1
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2007
    detail.hit.zdb_id: 1475085-5
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  • 10
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    Modulation of T Cell Cytokine Profiles and Peptide-MHC Complex Availability In Vivo by Delivery to Scavenger Receptors via Antigen Maleylation
    The American Association of Immunologists ; 1998
    In:  The Journal of Immunology Vol. 160, No. 10 ( 1998-05-15), p. 4869-4880
    Details
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 160, No. 10 ( 1998-05-15), p. 4869-4880
    Abstract: We have previously shown that conversion of proteins to scavenger receptor (SR) ligands by maleylation increases their immunogenicity. We now show that maleyl-Ag-immune spleen cells make relatively more IFN-γ and less IL-4 or IL-10 than native Ag-immune cells. This is also reflected in the IgG1:IgG2a ratios in Abs generated in vivo. SR engagement on macrophages does not alter their surface levels of the adhesive/costimulatory molecules CD11a/CD18, CD11b/CD18, CD24, CD54, or CD40, nor does it enhance their ability to support anti-CD3-driven proliferation of naive T cells in vitro. Costimulatory molecules implicated in differential Th1/Th2 commitment—CD80, CD86, and IL-12—are not inducible by SR ligation. In addition to macrophages and dendritic cells, B cells also show receptor-mediated uptake and enhanced presentation of maleyl-Ags. Using a monoclonal T cell line to detect peptide-MHC complexes expressed on spleen cells in Ag-injected mice, we find that higher levels of these complexes are generated in vivo from maleyl-proteins and they persist longer than those generated from the native protein. Together, these data suggest that in certain situations, the levels of cognate ligand available and/or the time course of their availability may play a major role in determining the cytokine profiles of the responding T cells in addition to the costimulatory signals implicated so far.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
    URL: Article
    DOI: 10.4049/jimmunol.160.10.4869
    RVK:
    XA 54100
    RVK:
    XA 10000
    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1998
    detail.hit.zdb_id: 1475085-5
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