NKAP is required for invariant natural killer T cell development and generation of ROR-γt expressing iNKT17 (LYM2P.738)

Abstract

Abstract iNKT cells differentiate into functional subsets defined as NKT1, NKT2 and NKT17, characterized by their expression of transcription factors, T-bet, GATA3 and ROR-γt and production of IFN-γ, IL-4 and IL-17, respectively. In our earlier studies, we showed that the transcriptional repressor NKAP is required for positive selection of DP thymocytes into the iNKT lineage, using CD4-cre NKAP conditional knockout (cKO) mice. To study the role of NKAP in subsequent stages of iNKT cell development and differentiation, we generated PLZF-cre NKAP cKO mice. In these mice, NKAP deletion occurs after entry into the iNKT lineage at stage 0, bypassing the requirement for NKAP in iNKT development at the DP stage. PLZF-cre NKAP cKO mice have a significant reduction in the absolute number of iNKT cells starting at Stage 1. This block in development is not due to defect in cell homeostasis or increased cell death, but is due to decreased rate of proliferation. PLZF-cre NKAP cKO mice have very few T-bet expressing NKT1 cells with similar amount of IFN-γ production to WT, whereas there was almost no ROR-γt expressing NKT17 cells with no IL-17 production. There is a decrease in the absolute number of NKT2 cells; however, IL-4 production by NKAP-deficient NKT2 cells is similar to WT. Thus, NKAP is required for proliferation of iNKT cells early in development, and is required for the differentiation of iNKT cells into the NKT17 lineage.