IL-7 and IL-15 play a synergistic role in the development of CD8+ T cell response against an obligate intracellular parasite (45.17)

Abstract

IL-7 and IL-15 are believed to be important for homeostatic proliferation of CD8⁺ memory T cells. However, the simultaneous role played by these two cytokines in the generation of this response during acute phase of infection has not been described. Our results demonstrate that depletion of IL-7 in mice lacking IL-15 gene leads to poor development of both short-lived effectors as well as memory phenotype CD8⁺ T cells during Toxoplasma gondii infection. CD8⁺ T cells from these animals lack the ability to produce optimal levels of IFNγ upon antigenic-restimulation and their ability to exhibit cytotoxic response is severely hampered. Moreover, Bcl-2 and KI-67 expression on these cells is down regulated. To the best of our knowledge this synergism between IL-7 and IL-15 in generating a potent CD8⁺ T cell immunity in an infectious disease model has not been previously reported.