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. 2021 Jan 22;11:602530. doi: 10.3389/fimmu.2020.602530

Figure 4.

Figure 4

Effects of cancer-associated fibroblasts (CAFs) on natural killer (NK) cell cytotoxic activity. Cytotoxic activity of NK cells co-cultured with fibroblasts was analyzed against CSFE-labeled K562 leukemic tumor cells at NK to target ratio of 5:1. Results were evaluated by flow cytometry and presented as percentage propidium-iodide positive (dead) cells versus side scatter activity (SSC). TGF-β treated NK cells served as control for repressed cytotoxic activity. Panels in (A) represent flow cytometry dot-plots from a representative experiment with one of the CAF donors. In (B), NK cell cytotoxic activity is represented as mean (± SD) values from flow experiments with three different CAF donors. Statistical P-values between mixed cultures with NF and CAFs were determined using one-way ANOVA with Tukey correction for multiple comparisons. Similarly, in (C), NK cell degranulation values are calculated as levels of LAMP-1 (CD107a) present on the NK cell surface after being employed against K562 leukemic tumor cells (for 4 h), at a NK to target ratio of 5:1, and an initial co-culturing with CAFs. Data represent mean (± SD) values from three different donors. * indicates P < 0.01.