IL-18Rα⁺ ILCs with similar properties are found in Rag1^−/− mouse lungs. (A) Lin⁻Tbet⁻Thy1⁺CD127⁺RORγt⁻ cells in adult Rag1^−/− mouse lungs were sequentially gated and divided into IL-18Rα⁺ST2⁻ (green) and IL-18Rα⁻ST2⁺ (black) subsets. (B) Expression of GATA-3 and CD25 by lung IL-18Rα⁺ ILCs (green) and ST2⁺ ILC2s (black) in A as well as lung NK cells (NKp46⁺Eomes⁺Tbet⁺; filled gray) is shown. (C) Lin⁻Thy1⁺CD127⁺ cells from Rag1^−/− mouse lungs were sorted into IL-18Rα⁺ ILCs (green) and ST2⁺ ILC2s (black) and stimulated for 72 h with PMA and ionomycin. The amounts of cytokines and chemokines in the culture supernatants were determined. (D) Absolute numbers of IL-18Rα⁺ ILCs (green) and ST2⁺ ILC2s (black) gated as in A in naive, IL-18, and papain-treated lungs are shown in bar graphs. (E) Lin⁻Thy1⁺CD127⁺IL-18Rα⁺ ILCs (green) and ST2⁺ ILC2s (black) were analyzed for intracellular IL-5 and IL-13 expression in naive, IL-18, and papain-treated lungs. Data are representative of five or more independent experiments with four or more mice per group in each experiment (mean ± SEM). **, P ≤ 0.01; ***, P ≤ 0.001 by two-tailed Student’s t test.