Densely granulated murine NK cells eradicate large solid tumors.

Area of Science:

• Immunology
• Oncology

Background:

• Natural killer (NK) cells are crucial for inhibiting early tumor development, recurrence, and metastasis.
• The capacity of NK cells to eliminate established, large solid tumors remains an area of active investigation.

Purpose of the Study:

• To investigate the mechanisms by which NK cells eradicate large solid tumors.
• To elucidate the role of interleukin 15 (IL-15) and NK cell morphology in tumor eradication and relapse prevention.

Main Methods:

• Analysis of NK cell infiltration, proliferation, and morphology within solid tumors.
• Assessment of perforin-mediated cytotoxicity.
• Investigation of the IL-15 receptor alpha (IL-15Rα) expression on cancer and stromal cells.

Main Results:

• NK cells eradicated large solid tumors through massive proliferation, driven by IL-15 produced by cancer cells.
• Infiltrating NK cells exhibited dense granulation, resembling uterine NK cells, and perforin-mediated killing was essential for tumor eradication.
• IL-15Rα expression on cancer cells induced granulated NK cells, while its expression on stromal cells prevented tumor relapse.

Conclusions:

• Interleukin 15 (IL-15) signaling at the tumor site induces highly activated, granulated NK cells capable of eradicating large solid tumors.
• NK cell activation and tumor microenvironment interactions are critical for both tumor destruction and prevention of relapse.