In vivo evidence for a dependence on interleukin 15 for survival of natural killer cells

Abstract

Cellular homeostasis requires a balance between cell production, cell survival, and cell death. Production of natural killer (NK) cells from bone marrow precursor cells requires interleukin 15 (IL-15); however, very little is known about the factors controlling survival of mature NK cells in vivo. Because mice deficient in IL-15 (IL-15-/- mice) fail to develop NK cells, it is not known whether mature NK cells can survive in an environment lacking IL-15. We hypothesized that IL-15 might indeed be required for survival of mature NK cells in vivo. Freshly isolated NK cells labeled with 5-(and-6)-carboxyfluorescein diacetate, succinimidyl ester (CFSE) were adoptively transferred into IL-15-/- mice and littermate control (IL-15+/-) mice. Within 36 hours after transfer, NK cells were detected in both IL-15-/- and IL-15+/- mice; however, significantly more (P