Abstract
The detection of microbial molecules via Toll-like receptors (TLR) in B cells is not well characterized. In this study, we found that both naive and memory B cells lack TLR4 (receptor for LPS) but express TLR9 (receptor for CpG motifs) and produce IL-6, TNF-alpha, and IL-10 upon stimulation with CpG oligonucleotides (ODN), synthetic mimics of microbial DNA. Consistent with the lack of TLR4, purified B cells failed to respond to LPS. Similar to CpG ODN, CD40 ligand (CD40L) alone induced IL-6, TNF-alpha, and IL-10. Production of these cytokines as well as IgM synthesis was synergistically increased when both CpG ODN and CD40L were combined. Unlike IL-6, TNF-alpha, and IL-10, the Th1 cytokine IL-12p70 was detected only when both CpG ODN and CD40L were present, and its induction was independent of B cell receptor cross-linking. CpG ODN did not increase the capacity of CD40L-activated B cells to induce proliferation of naive T cells. However, B cells activated with CpG ODN and CD40L strongly enhanced IFN-gamma production in developing CD4 T cells via IL-12. Together, these results demonstrate that IL-12p70 production in human B cells is under the dual control of microbial stimulation and T cell help. Our findings provide a molecular basis for the potent adjuvant activity of CpG ODN to support humoral immune responses observed in vivo, and for the limited value of LPS.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Adjuvants, Immunologic / physiology*
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B-Lymphocyte Subsets / immunology*
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B-Lymphocyte Subsets / metabolism
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CD40 Ligand / physiology*
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Cell Division / immunology
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Cells, Cultured
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CpG Islands / immunology*
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DNA-Binding Proteins / biosynthesis
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Down-Regulation / immunology
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Drug Synergism
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Humans
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Immunoglobulin M / biosynthesis
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Immunologic Memory
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Interleukin-10 / biosynthesis
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Interleukin-12 / antagonists & inhibitors
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Interleukin-12 / biosynthesis
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Interleukin-12 / physiology*
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Interleukin-4 / pharmacology
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Interleukin-6 / metabolism
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Interphase / immunology
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Lipopolysaccharides / pharmacology
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Lymphocyte Activation / immunology*
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Membrane Glycoproteins / metabolism
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Oligodeoxyribonucleotides / pharmacology*
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Protein Subunits / antagonists & inhibitors
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Protein Subunits / biosynthesis
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Protein Subunits / physiology*
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Receptors, Antigen, B-Cell / immunology
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Receptors, Antigen, B-Cell / metabolism
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Receptors, Antigen, B-Cell / physiology
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Receptors, Cell Surface / biosynthesis
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Receptors, Cell Surface / metabolism
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T-Lymphocyte Subsets / cytology
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T-Lymphocyte Subsets / immunology
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Th1 Cells / immunology*
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Th1 Cells / metabolism
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Toll-Like Receptor 4
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Toll-Like Receptor 9
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Toll-Like Receptors
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Tumor Necrosis Factor-alpha / biosynthesis
Substances
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Adjuvants, Immunologic
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CPG-oligonucleotide
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DNA-Binding Proteins
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Immunoglobulin M
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Interleukin-6
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Lipopolysaccharides
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Membrane Glycoproteins
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Oligodeoxyribonucleotides
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Protein Subunits
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Receptors, Antigen, B-Cell
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Receptors, Cell Surface
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TLR4 protein, human
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TLR9 protein, human
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Toll-Like Receptor 4
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Toll-Like Receptor 9
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Toll-Like Receptors
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Tumor Necrosis Factor-alpha
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Interleukin-10
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CD40 Ligand
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Interleukin-12
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Interleukin-4