Cytokine production and migration of in vitro-expanded NK1.1− invariant Vα14 natural killer T (Vα14i NKT) cells using α-galactosylceramide and IL-2

Mouse natural killer T cells with invariant Vα14 rearrangement (Vα14i NKT cells) can rapidly produce both Th1 and Th2 cytokines and regulate various immune responses, such as autoimmunity and tumor immunity. In this study, we describe the phenotypical and functional characterization of in vitro-expanded mouse Vα14i NKT cells from spleen using a combination of α-galactosylceramide (α-GalCer) and IL-2. The expanded Vα14i NKT cells retained the memory/activated (CD44+CD69+CD62L−) and CD4+ or CD4−8− double negative phenotypes but modulated or lost the classical NKT cell marker, NK1.1. The expanded Vα14i NKT cells continuously released IL-4 and IFNγ and induced NK cell IFNγ production in vitro. Furthermore, the expanded Vα14i NKT cells migrated into the liver and spleen after adoptive transfer into lymphopenic SCID mice, and they were able to rapidly produce IL-4 and IFNγ after α-GalCer injection. Our findings suggest that the intrinsic characteristics of the cytokine secretion of Vα14i NKT cells were equivalent to that of in vitro-expanded Vα14i NKT cells. In vitro-expanded Vα14i NKT cells are considered to be useful for NKT cell defect-related diseases, such as autoimmunity and cancer.