Over-expression of constitutively active PI3K p110γ alters NK cell development (134.4)

Abstract

Abstract PI3K is critical in NK cell responses such as cytokine production and cytotoxicity. The roles for the individual p110γ/δ isoforms in NK cell development and signaling are controversial. Over-expression of the p110γ/δ PI3K isoforms would help to dissect their roles in NK cells, however it is difficult to stably express proteins in NK cells. Therefore, we developed a novel system to over-express p110 in primary NK cells. IL2Rγc-/- mice lack NK cells and reconstitution of IL2Rγc-/- bone marrow (BM) with IL2Rγc restores NK cell development. Here, we describe a novel approach to produce NK cells in vivo, all of which express a "cargo" gene. This involves retroviral infection of IL2Rγc-/-/Rag2-/- BM with a construct containing a cargo gene followed by an IRES and IL2Rγc to permit selective NK cell development. Using EGFP as a control cargo protein, we showed that we can deliver EGFP to 100% of reconstituted NK cells. Constitutively active p110γ expressing NK cells display an immature phenotype and these cells do not produce IFNγ in response to NK1.1 stimulation or induce cytotoxicity in response to Yac1 cells. In contrast, constitutively active p110δ expressing NK cells display normal development, NK1.1-induced IFNγ production and cytotoxity. These data highlight the necessity for tight regulation of p110γ during NK cell development and function whereas regulation of p110δ is not as important for these processes.