title: CD40/CD154 interactions are required for the optimal maturation of skin-derived APCs and the induction of helminth-specific IFN-gamma but not IL-4.
abstract: The mechanisms through which Schistosoma mansoni larvae induce Th1 rather than Th2 immune responses are not well understood. In this study, using CD154-/- mice exposed to radiation-attenuated S. mansoni larvae, we demonstrate roles for CD154/CD40 in the activation of skin-derived APCs and the development of Th1 cells in the skin-draining lymph nodes (sdLN). The presence of CD154 was important for optimal IL-12p40 and essential for Ag-specific IFN-gamma, but CD154 expression by wild-type CD4- cells was insufficient to rescue recall responses of CD4+ cells from CD154-/- mice. This defect is probably due to impaired CD40-dependent IL-12 production in vivo, because administration of anti-CD40 Ab, or rIL-12, restored IFN-gamma production by sdLN cells from CD154-/- mice. CD154 ligation of CD40 was not required for the migration of skin-derived APCs, but did have a limited role in their maturation (increased MHC II and CD86). Unexpectedly, although CD4 cells from CD154-/- mice were deficient in their ability to produce IFN-gamma, they produced significant amounts of IL-4 and IL-5 in the presence of skin-derived APCs from wild-type and CD154-/- mice. Thus, in contrast to IFN-gamma, the production of Th2-associated cytokines is (in this model) independent of CD154. We conclude that whereas the priming of Th1 responses soon after exposure to schistosome larvae is completely CD40/CD154 dependent, IL-4, IL-5, and IL-13 are independent of CD154, suggesting a dichotomy in the specific mechanisms that induce these cytokines by CD4+ cells in the sdLN.
authors.affiliation: Department of Biology, University of York, York, United Kingdom.
authors.forename: James P
authors.initials: JP
authors.lastname: Hewitson
authors.forename: Gavin R
authors.initials: GR
authors.lastname: Jenkins
authors.forename: Paul A
authors.initials: PA
authors.lastname: Hamblin
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Mountford
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000276:immunology* / Q000378:metabolism; D023201:CD40 Ligand / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D006373:Helminthiasis / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D006376:Helminths / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000096:biosynthesis / Q000494:pharmacology; D015847:Interleukin-4 / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding; D012867:Skin / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D019013:CD40 Antigens; D023201:CD40 Ligand; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma