Tumor-associated NK cells drive MDSC-mediated tumor immune tolerance through the IL-6/STAT3 axis
Researchers investigated the interactions between a type of white blood cell called natural killer (NK) cells and a different category of blood cells called myeloid-derived suppressor cells (MDSCs) in patients whose tumors did not respond to immune checkpoint therapy. In the study they found that blood cells called monocytes and neutrophils that interact with NK cells that have encountered tumors suppressed immune responses. In a group of patients with sarcoma and breast cancer, they found that this was in part accomplished by the production of a protein called interleukin-6 (IL-6) by the tumor-infiltrating NK cells. Additionally, they found that inhibition of the IL-6 signaling reversed the immune suppression, resulting in reduced tumor growth and metastatic dissemination. These results indicate a NK cell-mediated mechanism that drives the development of MDSCs during tumor immune escape and may open additional therapeutic avenues for the treatment of sarcomas.