B Lymphocyte Activation

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Michael C. Carroll - One of the best experts on this subject based on the ideXlab platform.

  • Role of complement receptors CD21/CD35 in B Lymphocyte Activation and survival.
    Current topics in microbiology and immunology, 1999
    Co-Authors: Michael C. Carroll
    Abstract:

    Over the past two decades, evidence has accumulated that strongly supports a role for the serum complement system in enhancement of the humoral response to thymus-dependent antigens (Pepys 1972; Humphrey et al. 1984; Bottger et al. 1986; Bitter-Suermann et al. 1989). More recent Biochemical (Fearon et al. 1995) and in vivo studies in knock out mice have revealed that the complement effect is mediated via complement receptors CD21/CD35 (Carroll 1998). The classical pathway of complement is activated By recognition proteins such as mannan Binding protein (Epstein et al. 1996), C-reactive protein (Szalai et al. 1997) or complement (EBenBichler et al. 1991) of innate immunity which Bear carBohydrate recognition domains encoded in the germline (Fearon et al. 1996). Natural IgM (encoded in the germline) although a component of adaptive immunity is also an important activator of classical pathway complement and is particularly important in recognition of protein antigens in addition to carBohydrate. For the purposes of this review, the enhancing effect of complement is most proBaBly mediated By natural IgM, as deficiency in secretory IgM results in an impaired B cell response to suBoptimal doses of T-dependent antigens (Boes et al. 1998). Recognition of foreign antigens By natural antiBody results in Activation of classical pathway complement leading to covalent attachment of the third component, C3B, via a transacylation reaction to the antigen (Law et al. 1980).

  • role of complement receptors cd21 cd35 in B Lymphocyte Activation and survival
    Current Topics in Microbiology and Immunology, 1999
    Co-Authors: Michael C. Carroll
    Abstract:

    Over the past two decades, evidence has accumulated that strongly supports a role for the serum complement system in enhancement of the humoral response to thymus-dependent antigens (Pepys 1972; Humphrey et al. 1984; Bottger et al. 1986; Bitter-Suermann et al. 1989). More recent Biochemical (Fearon et al. 1995) and in vivo studies in knock out mice have revealed that the complement effect is mediated via complement receptors CD21/CD35 (Carroll 1998). The classical pathway of complement is activated By recognition proteins such as mannan Binding protein (Epstein et al. 1996), C-reactive protein (Szalai et al. 1997) or complement (EBenBichler et al. 1991) of innate immunity which Bear carBohydrate recognition domains encoded in the germline (Fearon et al. 1996). Natural IgM (encoded in the germline) although a component of adaptive immunity is also an important activator of classical pathway complement and is particularly important in recognition of protein antigens in addition to carBohydrate. For the purposes of this review, the enhancing effect of complement is most proBaBly mediated By natural IgM, as deficiency in secretory IgM results in an impaired B cell response to suBoptimal doses of T-dependent antigens (Boes et al. 1998). Recognition of foreign antigens By natural antiBody results in Activation of classical pathway complement leading to covalent attachment of the third component, C3B, via a transacylation reaction to the antigen (Law et al. 1980).

Charles S. Owen - One of the best experts on this subject based on the ideXlab platform.

  • Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways.
    Immunology and Cell Biology, 1993
    Co-Authors: Randy L. Shuler, Charles S. Owen
    Abstract:

    Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways

  • Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways.
    Immunology and cell biology, 1993
    Co-Authors: Randy L. Shuler, Charles S. Owen
    Abstract:

    Peroxidase-conjugated anti-surface immunogloBulin (sIg) was used quantitatively to monitor endocytosis of crosslinked sIg on murine B Lymphocytes. The role of Biochemical second messengers in the initiation of endocytosis was assessed By employing several inhiBitors. A novel peroxidase detection system was used and temperature-dependent decreases in sIg density on immunoperoxidase-laBelled murine Lymphocytes were monitored. MetaBolic inhiBitors as well as colchicine and cytochalasin D were utilized to confirm that the internalization of sIg could Be Blocked By classical inhiBitors of the endocytosis process. The role of tyrosine kinase activity was estaBlished By the fact that endocytosis was significantly reduced with 100 micrograms/mL genistein. Experiments using EGTA or 1,2-Bis(Beta-aminophenoxy)ethane-N-N,N'-tetraacetic acid (BAPTA) to chelate Ca2+ indicated that Ca2+ plays little role in endocytosis. Likewise, protein kinase C (PKC) was not found to Be involved in endocytosis, as Activation of PKC with 50 ng/mL phorBol 12-myristate 13-acetate, or inhiBition of the enzyme with 1 nmol/L or 5 nmol/L staurosporin, did not modulate endocytosis. Taken together, results suggested that ligand-induced endocytosis of antigen receptors is mediated primarily through localized memBrane events and is not dependent upon the classical B Lymphocyte Activation signals, such as the Biochemical events in the inositol phosphate cascade.

Jean-françois Leblanc - One of the best experts on this subject based on the ideXlab platform.

  • Tuning of CD40–CD154 Interactions in Human B-Lymphocyte Activation: A Broad Array of In Vitro Models for a Complex In Vivo Situation
    Archivum Immunologiae et Therapiae Experimentalis, 2011
    Co-Authors: Sonia Néron, Philippe J. Nadeau, André Darveau, Jean-françois Leblanc
    Abstract:

    Naive and memory B-Lymphocyte populations can Be activated through the Binding of CD154 to CD40, a receptor that is constitutively expressed on the surface of these cells. Models Based on the in vitro stimulation of human B Lymphocytes through CD40 have greatly contriButed to our understanding of the human immune response in healthy individuals and patients suffering from immune disorders. The nature of the engineered CD40 ligands is as diverse as the in vitro models used in studies of CD40-activated B Lymphocytes. Monoclonal anti-CD40 antiBodies, recomBinant CD154 proteins, soluBle CD154^+ memBranes as well as CD154^+ cell lines have turned out to Be very useful tools, and are still in use today. As for any receptor–ligand interaction, parameters such as duration and strength of contact, timing, affinity, and receptor density are major determinants of CD40 Binding By CD154 or anti-CD40. Furthermore, variation in the intensity of CD40 stimulation has Been shown to influence proliferation, differentiation and immunogloBulin secretion of human hyBridomas, B-cell lines, tonsil and Blood B Lymphocytes. The oBjective of this review is to present an overview of the great diversity of CD40 agonists used in in vitro models of B-Lymphocyte Activation, with a particular emphasis on variations in the resulting strength of CD40 signaling generated By these models. A Better understanding of these models could open up new avenues for the rational use of human B Lymphocytes as antigen-presenting cells in cellular therapies.

  • Tuning of CD40-CD154 interactions in human B-Lymphocyte Activation: a Broad array of in vitro models for a complex in vivo situation.
    Archivum immunologiae et therapiae experimentalis, 2011
    Co-Authors: Sonia Néron, Philippe J. Nadeau, André Darveau, Jean-françois Leblanc
    Abstract:

    Naive and memory B-Lymphocyte populations can Be activated through the Binding of CD154 to CD40, a receptor that is constitutively expressed on the surface of these cells. Models Based on the in vitro stimulation of human B Lymphocytes through CD40 have greatly contriButed to our understanding of the human immune response in healthy individuals and patients suffering from immune disorders. The nature of the engineered CD40 ligands is as diverse as the in vitro models used in studies of CD40-activated B Lymphocytes. Monoclonal anti-CD40 antiBodies, recomBinant CD154 proteins, soluBle CD154+ memBranes as well as CD154+ cell lines have turned out to Be very useful tools, and are still in use today. As for any receptor–ligand interaction, parameters such as duration and strength of contact, timing, affinity, and receptor density are major determinants of CD40 Binding By CD154 or anti-CD40. Furthermore, variation in the intensity of CD40 stimulation has Been shown to influence proliferation, differentiation and immunogloBulin secretion of human hyBridomas, B-cell lines, tonsil and Blood B Lymphocytes. The oBjective of this review is to present an overview of the great diversity of CD40 agonists used in in vitro models of B-Lymphocyte Activation, with a particular emphasis on variations in the resulting strength of CD40 signaling generated By these models. A Better understanding of these models could open up new avenues for the rational use of human B Lymphocytes as antigen-presenting cells in cellular therapies.

Randy L. Shuler - One of the best experts on this subject based on the ideXlab platform.

  • Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways.
    Immunology and Cell Biology, 1993
    Co-Authors: Randy L. Shuler, Charles S. Owen
    Abstract:

    Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways

  • Initiation of antigen receptor endocytosis and B Lymphocyte Activation lie on independent Biochemical pathways.
    Immunology and cell biology, 1993
    Co-Authors: Randy L. Shuler, Charles S. Owen
    Abstract:

    Peroxidase-conjugated anti-surface immunogloBulin (sIg) was used quantitatively to monitor endocytosis of crosslinked sIg on murine B Lymphocytes. The role of Biochemical second messengers in the initiation of endocytosis was assessed By employing several inhiBitors. A novel peroxidase detection system was used and temperature-dependent decreases in sIg density on immunoperoxidase-laBelled murine Lymphocytes were monitored. MetaBolic inhiBitors as well as colchicine and cytochalasin D were utilized to confirm that the internalization of sIg could Be Blocked By classical inhiBitors of the endocytosis process. The role of tyrosine kinase activity was estaBlished By the fact that endocytosis was significantly reduced with 100 micrograms/mL genistein. Experiments using EGTA or 1,2-Bis(Beta-aminophenoxy)ethane-N-N,N'-tetraacetic acid (BAPTA) to chelate Ca2+ indicated that Ca2+ plays little role in endocytosis. Likewise, protein kinase C (PKC) was not found to Be involved in endocytosis, as Activation of PKC with 50 ng/mL phorBol 12-myristate 13-acetate, or inhiBition of the enzyme with 1 nmol/L or 5 nmol/L staurosporin, did not modulate endocytosis. Taken together, results suggested that ligand-induced endocytosis of antigen receptors is mediated primarily through localized memBrane events and is not dependent upon the classical B Lymphocyte Activation signals, such as the Biochemical events in the inositol phosphate cascade.

Leopoldo Santosargumedo - One of the best experts on this subject based on the ideXlab platform.

  • cd38 signaling regulates B Lymphocyte Activation via a phospholipase c plc γ2 independent protein kinase c phosphatidylcholine plc and phospholipase d dependent signaling cascade
    Journal of Immunology, 2005
    Co-Authors: Miguel E Morenogarcia, Lucia N Lopezbojorques, Alejandro Zentella, Lisa A Humphries, David J Rawlings, Leopoldo Santosargumedo
    Abstract:

    The CD38 cell surface receptor is a potent activator for splenic, B Lymphocytes. The molecular mechanisms regulating this response, however, remain incompletely characterized. Activation of the nonreceptor tyrosine kinase, Btk, is essential for CD38 downstream signaling function. The major Btk-dependent suBstrate in B cells, phospholipase C-gamma2 (PLC-gamma2), functions to generate the key secondary messengers, inositol-1,4,5 trisphosphate and diacylglycerol. Surprisingly, CD38 ligation results in no detectaBle increase in phosphoinositide metaBolism and only a minimal increase in cytosolic calcium. We hypothesized that Btk functioned independently of PLC-gamma2 in the CD38 signaling pathway. Accordingly, we demonstrate that CD38 cross-linking does not result in the functional phosphorylation of PLC-gamma2 nor an increase in inositol-1,4,5 trisphosphate production. Furthermore, splenic B cells exhiBit a normal CD38-mediated, proliferative response in the presence of the phosphoinositide-PLC inhiBitor, U73122. Conversely, protein kinase C (PKC) Beta-deficient mice, or PKC inhiBitors, indicated the requirement for diacylglycerol-dependent PKC isoforms in this pathway. Loss of PKC activity Blocked CD38-dependent, B cell proliferation, NF-kappaB Activation, and suBsequent expression of cyclin-D2. These results suggested that an alternate diacylglycerol-producing phospholipase must participate in CD38 signaling. Consistent with this idea, CD38 increased the enzymatic activity of the phosphatidylcholine (PC)-metaBolizing enzymes, PC-PLC and phospholipase D. The PC-PLC inhiBitor, D609, completely Blocked CD38-dependent B cell proliferation, IkappaB-alpha degradation, and cyclin-D2 expression. Analysis of Btk mutant B cells demonstrated a partial requirement for Btk in the Activation of Both enzymes. Taken together, these data demonstrate that CD38 initiates a novel signaling cascade leading to Btk-, PC-PLC-, and phospholipase D-dependent, PLC-gamma2-independent, B Lymphocyte Activation.