AHR agonists suppress NK-cell function. (A-B) NK cells expanded using FC21 for 2 weeks with AHR agonist 25 μm Kyn or KA. The expanded NK cells were tested against calcein-labeled tumors: K562 or SJGBM2 cells. Mean specific lysis was determined using amount of calcein release. NK cells cell expanded using FC21 for 2 weeks. Following the expansion, NK cells were treated overnight with KA (25 μM) or DMSO (control) and then cocultured with calcein-labeled tumors at various E:T for 4 hours. Representative plot showing standard cytotoxicity assay against (C) HS578T cells and (E) SJGBM2 cells. Percent lysis calculated relative to the control group shown in panels D and F. Data show mean ± standard error of the mean (n = 3; P < .01).