Adjuvant IL-15 does not enhance the efficacy of tumor cell lysate-pulsed dendritic cell vaccines for active immunotherapy of T cell lymphoma

Erin Gatza, Craig Y. Okada

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


There has been a recent interest in using IL-15 to enhance antitumor activity in several models because of its ability to stimulate CD8+ T cell expansion, inhibit apoptosis and promote memory T cell survival and maintenance. Previously, we reported that C6VL tumor lysate-pulsed dendritic cell vaccines significantly enhanced the survival of tumor-bearing mice by stimulating a potent tumor-specific CD8+ T cell response. In this study, we determined whether IL-15 used as immunologic adjuvant would augment vaccine-primed CD8+ T cell immunity against C6VL and further improve the survival of tumor-bearing mice. We report that IL-15 given after C6VL lysate-pulsed dendritic cell vaccines stimulated local and systemic expansion of NK, NKT and CD8+ CD44hi T cells. IL-15 did not, however, augment innate or cellular responses against the tumor. T cells from mice infused with IL-15 following vaccination did not secrete increased levels of tumor-specific TNF-α or IFN-γ or have enhanced C6VL-specific CTL activity compared to T cells from recipients of the vaccine alone. Lastly, IL-15 did not enhance the survival of tumor-bearing vaccinated mice. Thus, while activated- and memory-phenotype CD8+ T cells were dramatically expanded by IL-15 infusion, vaccine-primed CD8+ T cells specific for C6VL were not significantly expanded. This is the first account of using IL-15 as an adjuvant in a therapeutic model of active immunotherapy where there was not a preexisting pool of tumor-specific CD8+ T cells. Our results contrast the recent studies where IL-15 was successfully used to augment tumor-reactivity of adoptively transferred transgenic CD8+ T cells. This suggests that the adjuvant potential of IL-15 may be greatest in settings where it can augment the number and activity of preexisting tumor-specific CD8+ T cells.

Original languageEnglish (US)
Pages (from-to)420-432
Number of pages13
JournalCancer Immunology, Immunotherapy
Issue number4
StatePublished - Apr 2006


  • Dendritic cells
  • Interleukin-15
  • Tumor immunity
  • Vaccination

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Oncology
  • Cancer Research


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