The Dark Side of NK Cells in Cancer Immunotherapy

NK cells are a subset of innate lymphoid cells originally identified in mice and humans based on their ability to mediate cytotoxicity against transformed cells. However, two recent back-to-back studies in this issue of Cancer Discovery reveal that NK cell infiltration is not always beneficial; rather, it can impair the efficacy of immune checkpoint blockade through immune-regulatory mechanisms. See related article by Pozniak et al., p. 1819 See related article by Song et al., p. 1835.