title: Activation of human neonatal monocyte-derived dendritic cells by lipopolysaccharide down-regulates birch allergen-induced Th2 differentiation.
abstract: Epidemiological studies describe an inverse association between the level of environmental endotoxin exposure during infancy and the prevalence of allergic disease in children. To study the effect of lipopolysaccharide (LPS) and lipopeptide Pam3Cys signaling via Toll-like receptor (TLR)4 and TLR2 on dendritic cells (DC), respectively, on birch allergen-induced T cell differentiation, cord blood monocyte-derived DC were exposed to birch allergen extract alone or in combination with LPS or Pam3Cys and thereafter co-cultured with naive autologous T cells. We demonstrate that birch allergen alone induced high levels of IL-13 from neonatal T cells, whereas the production of IL-5 and IFN-gamma was modest. Stimulation of DC with birch allergen together with LPS but not Pam3Cys resulted in a decreased IL-13 production by T cells compared to birch allergen alone. Furthermore, birch allergen together with LPS induced increased up-regulation of activation markers expressed on the surface and production of cytokines from DC relative to stimulation with birch allergen alone. Finally, birch allergen partially suppressed both LPS- and Pam3Cys-induced DC maturation. Our results indicate that concomitant TLR4 stimulation during the initial phase of immune activation to birch allergen in infants may inhibit the development of a T helper 2-type response.
authors.affiliation: Department of Rheumatology and Inflammation Research, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden.
authors.forename: Anna-Carin
authors.initials: AC
authors.lastname: Andersson
authors.forename: Ulla
authors.initials: U
authors.lastname: Seppälä
authors.forename: Anna
authors.initials: A
authors.lastname: Rudin
mesh_terms: D029662:Betula / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D015536:Down-Regulation / Q000276:immunology; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000819:agonists / Q000276:immunology; D011956:Receptors, Cell Surface / Q000819:agonists / Q000276:immunology; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors