Fig. 4.

Loss of NK cell IFNAR1 impairs poly I:C-induced tumor cell killing due to decreased NK cell activation and degranulation. In vivo poly I:C-activated (25 μg, IP, 24 h prior to spleen excision) NK cells were purified from control^iCre or Ifnar^−/−NKp46 mice (n = 3/group) and cocultured with calcein-AM-labelled a EO771.LMB cells for 4 h, after which the percentage of target cell lysis was quantitated and NK cells recovered for flow cytometric analysis of b CD69⁺ and c CD107a⁺ NK1.1⁺ cell frequency (%) (d representative flow cytometry plots shown); or e B16F10 cells for 4 h, after which the percentage of target cell lysis was quantitated and NK cells recovered for flow cytometric analysis of f CD69⁺ and g CD107a⁺ NK1.1⁺ cell frequency (%). NK cell degranulation (CD107a⁺) was assessed post-coculture of NK cells purified from naïve control^iCre or Ifnar^−/−NKp46 mice (n = 3/group) with h EO771.LMB cells and i B16F10 cells. j Baseline poly I:C-activated NK cell degranulation (no targets) also shown. p values * < 0.05, ** < 0.005, determined by Student’s t test. Errors bars, SEM