title: Activated human neonatal CD8+ T cells are subject to immunomodulation by direct TLR2 or TLR5 stimulation.
abstract: In conditions of optimal priming, the neonate possesses competency to mount quantitatively adult-like responses. Vaccine formulations containing sufficiently potent adjuvants may overcome the neonate's natural tendency for immunosuppression and provoke a similarly robust immune response. TLR expression on T cells represents the possibility of directly enhancing T cell immunity. We examined the ex vivo responsiveness of highly purified human cord blood-derived CD8(+) T cells to direct TLR ligation by a repertoire of TLR agonists. In concert with TCR stimulation, only Pam(3)Cys (palmitoyl-3-Cys-Ser-(Lys)(4)) and flagellin monomers significantly enhanced proliferation, CD25(+) expression, IL-2, IFN-gamma, TNF-alpha, and intracellular granzyme B expression. TLR2 and TLR5 mRNA was detected in the CD8(+) T cells. Blocking studies confirmed that the increase in IFN-gamma production was by the direct triggering of surface TLR2 or TLR5. The simultaneous exposure of CD8(+) T cells to both TLR agonists had an additive effect on IFN-gamma production. These data suggest that a combination of the two TLR ligands would be a potent T cell adjuvant. This may represent a new approach to TLR agonist-based adjuvant design for future human neonatal vaccination strategies requiring a CD8(+) component.
authors.affiliation: Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland. mark.mccarron@ucd.ie
authors.forename: Mark
authors.initials: M
authors.lastname: McCarron
authors.forename: Denis J
authors.initials: DJ
authors.lastname: Reen
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000494:pharmacology*; D000938:Antigen-Presenting Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004151:Dipeptides / Q000494:pharmacology; D005312:Fetal Blood / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D005408:Flagellin / Q000494:pharmacology; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects; D007231:Infant, Newborn; D008024:Ligands; D008074:Lipoproteins / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051198:Toll-Like Receptor 5 / Q000819:agonists / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D004151:Dipeptides; D008024:Ligands; D008074:Lipoproteins; C495342:TLR2 protein, human; C495346:TLR5 protein, human; D051195:Toll-Like Receptor 2; D051198:Toll-Like Receptor 5; D005408:Flagellin; C047210:2,3-bis-(palmitoyloxy)-2-propyl-N-palmitoyl-cysteinylserine