Abstract
CD40 ligand (CD40L) is present on activated but not on resting T cells. In contrast to the activation markers CD25 and CD71, a strong CD40L expression could be induced by calcium ionophore alone but not by phorbol 12-myristate 13-acetate (PMA). Ionomycin induced a very early mRNA and protein surface expression of CD40L within the first 2 h, whereas CD25 and CD71 did not appear earlier than 6 h after stimulation. The mitogens phytohemagglutinin and concanavalin A induced little CD40L, but together with PMA, a markedly increased CD40L expression was observed. In T cells stimulated with immobilized anti-CD3, co-stimulation with anti-CD28 or PMA induced an earlier and higher maximal CD40L expression. CD40L expression of purified T cells was higher and more prolonged compared to that of T cells in unseparated peripheral blood mononuclear cells. We conclude that the expression of CD40L on T cells is profoundly different from other early activation markers with regard to signal requirements, kinetics and the role of accessory cells in the system.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Antibodies, Monoclonal / immunology
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Antibodies, Monoclonal / pharmacology
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Antigens, CD / analysis
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Antigens, Differentiation, B-Lymphocyte / analysis
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CD28 Antigens / immunology
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CD3 Complex / immunology
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CD40 Ligand
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Calcium / physiology*
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Cell Separation
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Cyclosporine / pharmacology
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Egtazic Acid / pharmacology
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Enzyme Activation
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Gene Expression Regulation / physiology*
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Humans
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Intracellular Fluid
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Ionomycin / pharmacology
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Ionophores / pharmacology
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Lymphocyte Activation* / drug effects
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Membrane Glycoproteins / biosynthesis*
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Membrane Glycoproteins / genetics
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Mitogens / pharmacology
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Protein Kinase C / metabolism
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Receptors, Interleukin-2 / analysis
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Receptors, Transferrin
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T-Lymphocytes / drug effects
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T-Lymphocytes / immunology*
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T-Lymphocytes / metabolism
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Tetradecanoylphorbol Acetate / pharmacology
Substances
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Antibodies, Monoclonal
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Antigens, CD
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Antigens, Differentiation, B-Lymphocyte
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CD28 Antigens
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CD3 Complex
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CD71 antigen
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Ionophores
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Membrane Glycoproteins
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Mitogens
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Receptors, Interleukin-2
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Receptors, Transferrin
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CD40 Ligand
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Egtazic Acid
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Ionomycin
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Cyclosporine
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Protein Kinase C
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Tetradecanoylphorbol Acetate
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Calcium