title: Interleukin-15 enhances T-cell responses by stimulation with dendritic cells.
abstract: BACKGROUND
  Cytokines play important roles in regulating immune responses. Interleukin-2 (IL-2) has usually been used as an adjuvant to enhance antitumour immune responses. However, its crucial role in activation-induced cell death, inhibition of homeostatic proliferation of CD8+ memory T cells and its notable biological side effects impair its prospect of application. IL-15 has several similar functions to IL-2 and shows potential advantages over IL-2, and is being investigated to enhance antitumour dendritic cell (DC) vaccine strategies in our ongoing studies.
  
  
  OBJECTIVE
  In this preliminary study, we evaluated the ability of IL-15, compared with IL-2, to act as an adjuvant to enhance T-cell responses activated by DCs in vitro.
  
  
  METHODS
  Bone marrow-derived DCs (BMDCs) were pulsed with tumour antigens and used to stimulate lymphocyte responses in the presence of IL-15 or IL-2. The activated T lymphocytes were examined by flow cytometric analysis, and interferon-γ (IFN-γ) enzyme-linked immunospot and cytotoxicity assays.
  
  
  RESULTS
  IL-15 was observed to activate lymphocytes with comparable phenotype characteristics of activated/memory CD8+ lymphocytes, compared with IL-2. Both in primary and secondary stimulation with DCs, when using IL-15 as an adjuvant, activated lymphocytes showed higher proportions of IFN-γ-secreting subsets. In secondary stimulation with BMDCs in the presence of IL-15, the activated lymphocytes showed a stronger cytotoxicity to antigen-specific tumour target cells.
  
  
  CONCLUSIONS
  Our study suggested that IL-15 might be a prospective adjuvant for a DC vaccine strategy against cancers. The further observation that IL-15 acts as an adjuvant for an antitumour DC vaccine strategy is worth investigating.
authors.affiliation: Department of Medical Oncology, Cancer Center, and State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, Sichuan Province, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhao
authors.forename: Ke
authors.initials: K
authors.lastname: Cheng
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.forename: Xing-Chen
authors.initials: XC
authors.lastname: Peng
authors.forename: Ye
authors.initials: Y
authors.lastname: Chen
authors.forename: Ben-Xu
authors.initials: BX
authors.lastname: Tan
authors.forename: Jun
authors.initials: J
authors.lastname: Ge
authors.forename: Hang
authors.initials: H
authors.lastname: Dong
authors.forename: Meng
authors.initials: M
authors.lastname: Wei
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Jing-Mei
authors.initials: JM
authors.lastname: Su
authors.forename: Jian-Mei
authors.initials: JM
authors.lastname: Hou
authors.forename: Ji-Yan
authors.initials: JY
authors.lastname: Liu
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology; D002469:Cell Separation; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D019409:Interleukin-15 / Q000276:immunology* / Q000494:pharmacology; D007376:Interleukin-2 / Q000276:immunology / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*
chemical_list: D019409:Interleukin-15; D007376:Interleukin-2