IL‐12 and IL‐15 induce the expression of CXCR6 and CD49a on peripheral natural killer cells

INTRODUCTION: Murine hepatic NK cells exhibit adaptive features, with liver‐specific adhesion molecules CXCR6 and CD49a acting as surface markers. METHODS: We investigated human liver‐resident CXCR6+ and CD49a+ NK cells using RNA sequencing, flow cytometry, and functional analysis. We further assessed the role of cytokines in generating NK cells with these phenotypes from the peripheral blood. RESULTS: Hepatic CD49a+ NK cells could be induced using cytokines and produce high quantities of IFNγ and TNFα, in contrast to hepatic CXCR6+ NK cells. RNA sequencing of liver‐resident CXCR6+ NK cells confirmed a tolerant immature phenotype with reduced expression of markers associated with maturity and cytotoxicity. Liver‐resident double‐positive CXCR6 + CD49a+ hepatic NK cells are immature but maintain high expression of Th1 cytokines as observed for single‐positive CD49a+ NK cells. We show that stimulation with activating cytokines can readily induce upregulation of both CD49a and CXCR6 on NK cells in the peripheral blood. In particular, IL‐12 and IL‐15 can generate CXCR6 + CD49a+ NK cells in vitro from NK cells isolated from the peripheral blood, with comparable phenotypic and functional features to liver‐resident CD49a+ NK cells, including enhanced IFNγ and NKG2C expression. CONCLUSION: IL‐12 and IL‐15 may be key for generating NK cells with a tissue‐homing phenotype and strong Th1 cytokine profile in the blood, and links peripheral activation of NK cells with tissue‐homing. These findings may have important therapeutic implications for immunotherapy of chronic liver disease.