Development of Functional Human NK Cells in an Immunodeficient Mouse Model with the Ability to Provide Protection against Tumor Challenge

Studies of human NK cells and their role in tumor suppression have largely been restricted to in vitro experiments which lack the complexity of whole organisms, or mouse models which differ significantly from humans. In this study we showed that, in contrast to C57BL/6 Rag2^−/−/γ_c^−/− and NOD/Scid mice, newborn BALB/c Rag2^−/−/γ_c^−/− mice can support the development of human NK cells and CD56+ T cells after intrahepatic injection with hematopoietic stem cells. The human CD56⁺ cells in BALB/c Rag2^−/−/γ_c^−/− mice were able to produce IFN-γ in response to human IL-15 and polyI:C. NK cells from reconstituted Rag2^−/−/γ_c^−/− mice were also able to kill and inhibit the growth of K562 cells in vitro and were able to produce IFN-γ in response to stimulation with K562 cells. In vivo, reconstituted Rag2^−/−/γ_c^−/− mice had higher survival rates after K562 challenge compared to non-reconstituted Rag2^−/−/γ_c^−/− mice and were able to control tumor burden in various organs. Reconstituted Rag2^−/−/γ_c^−/− mice represent a model in which functional human NK and CD56+ T cells can develop from stem cells and can thus be used to study human disease in a more clinically relevant environment.