title: Combined TLR stimulation with Pam3Cys and Poly I: C enhances Flt3-ligand dendritic cell activation for tumor immunotherapy.
abstract: The cytokines granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 are frequently used for generating dendritic cells (DCs) for therapeutic vaccination against cancer. These in vitro DCs share several characteristics with inflammatory monocyte-derived DCs in vivo. In contrast, culture of bone marrow cells in Flt3-ligand (Flt3L) generates a heterogeneous population of DCs, which comprise conventional DCs (cDCs) and plasmacytoid DCs similar to the steady-state populations found in vivo. Although previous studies have identified combinations of toll-like receptor ligands (TLR-Ls) that induce optimal activation of GM-CSF/IL-4 DCs in vitro, the conditions for optimal activation of Flt3L-DCs have not been established. In this study, we show that various combinations of the TLR-Ls Pam3Cys, Poly I:C, lipopolysaccharide, and CpG all increased Flt3L-DC maturation, but only the combination of Pam3Cys/Poly I:C showed a trend to enhanced production of IL-12p70 and tumor necrosis factor-α by cDCs. Pam3Cys/Poly I:C-treated cDCs also displayed enhanced capacity to present antigen to CD4(+) T cells, and cross-present to CD8(+) T cells, increasing T-cell proliferation in vitro. Within a prophylactic vaccination setting, cDCs activated with Pam3Cys/Poly I:C conferred tumor protection in mice. However, the numbers of cDCs required for protection were higher than the numbers of optimally activated GM-CSF/IL-4 DCs required for a similar effect. Our results show that combined TLR stimulation can enhance both the phenotypic and functional properties of Flt3L-DCs, but even under conditions of optimal activation these cells are not superior in activity to GM-CSF/IL-4 DCs in vivo.
authors.affiliation: Malaghan Institute of Medical Research, Victoria University of Wellington, Wellington, New Zealand.
authors.forename: So Nai
authors.initials: SN
authors.lastname: Lim
authors.forename: Sabine
authors.initials: S
authors.lastname: Kuhn
authors.forename: Evelyn
authors.initials: E
authors.lastname: Hyde
authors.forename: Franca
authors.initials: F
authors.lastname: Ronchese
mesh_terms: D000818:Animals; D019496:Cancer Vaccines; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D007167:Immunotherapy; D018836:Inflammation Mediators / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology; D008074:Lipoproteins / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009369:Neoplasms / Q000276:immunology* / Q000401:mortality / Q000628:therapy*; D011070:Poly I-C / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D051193:Toll-Like Receptors / Q000819:agonists / Q000378:metabolism*
chemical_list: D019496:Cancer Vaccines; D016207:Cytokines; D018836:Inflammation Mediators; D008074:Lipoproteins; D008565:Membrane Proteins; D051193:Toll-Like Receptors; C084881:flt3 ligand protein; C061108:N-palmitoyl-S-(2,3-bis(palmitoyloxy)propyl)cysteinyl-seryl-lysyl-lysyl-lysyl-lysine; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011070:Poly I-C