IL-18-primed helper NK cells collaborate with dendritic cells to promote recruitment of effector CD8+ T cells to the tumor microenvironment

摘要

Chemokine-driven interactions of immune cells are essential for effective anti-tumor immunity. Human natural killer (NK) cells can be primed by the IL1-related pro-inflammatory cytokine IL-18 for unique helper activity, which promotes dendritic cell (DC) activation and DC-mediated induction of type-1 immune responses against cancer. Here we show that such IL-18-primed ‘helper’ NK cells produce high levels of the immature DC (iDC)-attracting chemokines CCL3 and CCL4 upon exposure to tumor cells or the additional inflammatory signals IFNα, IL-15, IL-12, or IL-2. These ‘helper’ NK cells potently attract iDCs in a CCR5-dependent mechanism and induce high DC production of CXCR3 and CCR5 ligands (CXCL9, CXCL10, and CCL5), facilitating the subsequent recruitment of type-1 effector CD8⁺ T (Teff) cells. Using cells isolated from the malignant ascites of patients with advanced ovarian cancer, we show that ‘helper’ NK cell-inducing factors can be used to enhance local production of Teff cell-recruiting chemokines. Our findings reveal the unique chemokine expression profile of ‘helper’ NK cells and highlight the potential for utilizing two-signal-activated NK cells to promote homing of type-1 immune effectors to the human tumor environment.