Figure 1. Better control of B16 melanoma by Klrk1^-/- mice is NK cell and IFNγ mediated.

(a) Survival curve of C57BL/6J and Klrk1^-/- mice in model of radiation induced thymic lymphomas. Graphs show survival curves (b,e,g) or tumor sizes (c,f) of Klrk1^-/- mice and indicated controls after injection of B16 cells i.v (b,e,g) or s.c. (c,f). One day prior to tumor inoculation, mice were either untreated (b, c) or received depleting antibodies directed against NK cells (e, f) or CD8+ T cells (g). Depletion was repeated every fifth day. (d) Survival curve of Klrk1 ^fl/fl and CD4^CreKlrk1^fl/fl mice which received B16 cells i.v.. (h) Killing capacity of NK cells from C57BL/6J or Klrk1^-/- mice toward CFSE- labeled B16 cells after 4h of co-cultivation at indicated effector to target (E:T) ratios. (i) Cytokine production by NK cells from C57BL/6J or Klrk1^-/- mice 4h after PMA/Ionomycin stimulation. (j) IFN-γ production by NK cells after co-cultivation of splenocytes from Klrk1^+/+ and Klrk1^-/- mice with B16 cell. (k) Survival curve of Ifng^-/-, Klrk1^-/-Ifng^-/- and Klrk1^-/- mice after B16 cells i.v. injection. Graphs for tumor experiments (a-g and k; n=10 mice per group) are representative from 2 independent experiments. Survival curves were analyzed by the Kaplan–Meier model followed by Log-rank (Mantel-Cox) test (two-tailed; **p < 0.01, *** p <0.001). Tumor sizes and difference between groups after stimulations were analyzed using two-tailed unpaired t-test (shown mean ± s.e.m); **P < 0.01. Results in h, i and j (n=5 mice per group) are representative from 2 independent experiments. b-d and j are performed using littermates.