SG trNK cells contain a cytotoxic subset that is present in multiple glandular tissues. (A) High-dimensional flow cytometry of adult WT and Ncr1^CreTgfb1^fl SG group 1 ILCs shown as UMAP with FlowSOM clustering and corresponding heatmap displaying relative marker expression in identified cell populations. (B) Cluster frequency in SGs of indicated genotype. (C) Overlay of indicated markers on UMAP with all group 1 ILCs. Color shows normalized expression. (D) Representative flow cytometry plot of GzmB and -C expression in all (grey) or CD103⁺ (green) SG trNK cells. (E) Flow cytometric quantification of GzmB⁺ and GzmC⁺ cells in indicated SG group 1 ILC populations. (F and G) Representative flow cytometry plots of trNK cells (F) and subset composition (G) in indicated organs. (H) Immunofluorescence staining showing DAPI (blue), NKp46-TdTomato (magenta), GzmB (yellow), and EpCAM (teal) in indicated organs of Ncr1^CreR26R^Ai14 mice. Scale bars, 50 μm (pancreas) or 25 μm (rest). (I and J) Heatmap showing percentage of Ly49 marker-positive cells (I) and histogram with Perforin expression among SG group 1 ILCs (J), measured with flow cytometry. (K) Percentage of IFN-γ⁺ SG group 1 ILCs after stimulation with PMA/Iono or IL-12 and IL-18 for 4 h. (L) YAC-1 cells (target, T) were cultured for 6 h at indicated ratio with effector (E) cells. Percentage of dead YAC-1 cells was measured with flow cytometry. (A–C) Data from one representative experiment with total n = 5–7 mice per group, or (D–G and I–K) from one representative of two to three independent experiments with n = 4–7 mice, (H) representative for n = 2–5 mice, or (L) representative for one of two experiments. Error bars display means ± SD. Statistical significance was calculated using one-way ANOVA or two-tailed t test; **P < 0.01 and ****P < 0.0001. ns, not significant.