IL-15 as a mediator of CD4+ help for CD8+ T cell longevity and avoidance of TRAIL-mediated apoptosis

Sang Kon Oh, Liyanage P. Perera, Masaki Terabe, Ling Ni, Thomas A. Waldmann, Jay A. Berzofsky

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


CD4+ helper T cells contribute to the induction and maintenance of antigen-specific CD8+ T cells. Their absence results in short-lived antigen-specific CD8+ T cells and defective secondary CD8+ T cell responses because of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. Here, we show that IL-15 codelivered with vaccines can overcome CD4+ T cell deficiency for promoting longevity of antigen-specific CD8+ T cells and avoidance of TRAIL-mediated apoptosis. In both priming and secondary responses, IL-15 down-regulates proapoptotic Bax, an intermediate in TRAIL-mediated apoptosis, and increases anti-apoptotic Bcl-XL in CD8+ T cells. Thus, IL-15 is sufficient to mimic CD4+ T cell help. Antigen-specific CD4+ T cells induce dendritic cells (DCs) to produce IL-15. IL-15 is also necessary for optimal help, because helper cells do not deliver effective help through IL-15-/- DCs. Therefore, IL-15 codelivered with vaccines can overcome CD4+ helper T cell deficiency for induction of functionally efficient CD8+ T cells and maintenance of CD8 + cytotoxic T lymphocytes (CTLs), and IL-15 is probably one of the natural mediators of help. These findings suggest new vaccine strategies against infections and cancers, especially in individuals with CD4-deficiency.

Original languageEnglish (US)
Pages (from-to)5201-5206
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number13
StatePublished - Apr 1 2008


  • Cytotoxic T lymphocytes
  • T cell help

ASJC Scopus subject areas

  • General


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