Fig. 2
From: NK cells and solid tumors: therapeutic potential and persisting obstacles
Immunological and stromal barriers against optimal NK cell activity in solid tumors. Tumor-infiltrating natural killer (NK) cells engage in contact-dependent and independent interactions with a variety of cells that ultimately inhibit their anticancer activity. Such cells include not only regulatory T (TREG) cells, M2-like tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), but also cancer-associated fibroblasts (CAFs). ARG1, arginase 1; IDO1, indoleamine 2,3-dioxygenase 1; IL, interleukin; MMP, metalloprotease; NO, nitric oxide; PGE2, prostaglandin E2; ROS, reactive oxygen species; TGFB1, transforming growth factor beta 1