Abstract
Toll-like receptor (TLR)-4 signaling pathway plays an essential role in host defense against gram-negative bacteria while TLR-3-mediated signaling is critically involved in anti-viral immunity. To gain insight into the defects responsible for impaired Th1 responses in human newborns, we investigated the responses of human cord blood cells to lipopolysaccharide, LPS, and to polyinosinic-polycytidylic acid, Poly (I:C), ligands of TLR-4 and TLR-3, respectively. Measurement of cytokine levels revealed a profound defect in IL-12 (p70) synthesis and an increased release of IL-10 in cord blood exposed to LPS or Poly (I:C), as compared to adult blood. Moreover, Poly (I:C)-induced IFN-alpha production was found to be significantly impaired in cord blood. Phenotypic maturation of myeloid DC in response to LPS or Poly (I:C) was next compared in cord and adult blood. We observed that neonatal myeloid DC displayed decreased upregulation of CD40, CD80 whereas CD86 and HLA-DR upregulation did not differ significantly between adults and neonates. Taken together, these findings might be relevant to the increased vulnerability of human newborns to intracellular pathogens and to their inability to develop efficient Th1-type responses.
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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Adult
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Antigens, CD / metabolism
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B7-1 Antigen / metabolism
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B7-2 Antigen
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CD40 Antigens / metabolism
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Dendritic Cells / chemistry
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Dendritic Cells / drug effects
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Dendritic Cells / metabolism
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Fetal Blood / cytology
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Fetal Blood / drug effects*
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Fetal Blood / metabolism
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Flow Cytometry
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HLA-DR Antigens / metabolism
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Humans
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Infant, Newborn
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Interferon-alpha / analysis
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Interferon-alpha / metabolism
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Interleukin-10 / metabolism
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Interleukin-12 / metabolism
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Leukocytes, Mononuclear / drug effects
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Leukocytes, Mononuclear / metabolism
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Lipopolysaccharides / pharmacology*
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Membrane Glycoproteins / metabolism
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Membrane Glycoproteins / physiology*
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Poly I-C / pharmacology*
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Receptors, Cell Surface / physiology*
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Th1 Cells / immunology
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Toll-Like Receptor 3
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Toll-Like Receptor 4
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Toll-Like Receptors
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Tumor Necrosis Factor-alpha / metabolism
Substances
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Antigens, CD
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B7-1 Antigen
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B7-2 Antigen
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CD40 Antigens
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CD86 protein, human
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HLA-DR Antigens
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Interferon-alpha
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Lipopolysaccharides
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Membrane Glycoproteins
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Receptors, Cell Surface
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TLR3 protein, human
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TLR4 protein, human
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Toll-Like Receptor 3
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Toll-Like Receptor 4
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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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Interleukin-12
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Poly I-C