Cytokine-Based Generation of CD49a + Eomes -/+ Natural Killer Cell Subsets.

Recent studies have identified CD49a(+)Eomes(-) and CD49a(+)Eomes(+) subsets of tissue-resident NK (trNK) cells in different organs of the mouse. However, the characteristics of CD49a(+)Eomes(-/+) NK cell development and the regulation of Eomes expression in NK cells remain unclear. Here, we established an in vitro cytokine-based feeder-free system in which bone marrow progenitor cells differentiate into CD49a(+) NK cells. IL-15 was identified as being the key cytokine in this system that supported the development and maintenance of CD49a(+) NK cells. The CD49a(+) NK cells generated were Eomes(-)CD49b(-) and shared the same phenotype as hepatic trNK cells. IL-4 induced the expression of Eomes in generated NK cells and converted them into CD49a(+)Eomes(+) cells, which were phenotypically and functionally similar to uterine trNK cells. Moreover, the IL-4/STAT6 axis was identified as being important in the generation of CD49a(+)Eomes(+) induced NK cells. Collectively, these studies describe an approach to generate CD49a(+)Eomes(-/+) subsets of NK cells and demonstrate important roles for IL-15 and IL-4 in the differentiation of these cells. These findings have potential for developmental research underlying the generation of different subsets of NK cells and the application of adoptive NK cell transfer therapies.