IL-18Rα⁺ ILCs in adult Rag1^−/− mouse lungs have ILCP properties. BM ILCPs or lung Lin⁻Thy1⁺CD127⁺IL-18Rα⁺ST2⁻ cells were purified from papain-treated Rag1^−/− mice (CD45.2) and injected (4,000 cells per mouse) intravenously into lethally irradiated Pep3b mice. The tissues of the recipient mice were analyzed 6 wk after transplantation. (A) Lung Lin⁻T-bet⁻Thy1⁺CD127⁺Rorγt⁻ cells were sequentially gated, and IL-18Rα⁺ and ST2⁺ subsets were analyzed for donor-derived CD45.1⁻CD45.2⁺ cells. (B) Liver T-bet⁺Eomes⁻ and T-bet⁺Eomes⁺ cells were gated for donor-derived ILC1s and NK cells. (C) Absolute numbers of donor-derived lung ILC2s, liver ILC1s, and NK cells. (D) BM ILCPs or lung IL-18Rα⁺ ILCs were purified as in A, and 1,000 cells each were cultured as in Fig. 4 D. The progenies were analyzed for Thy1 and NKp46 expression. Thy1⁺NKp46⁻ cells were further analyzed for ICOS expression. Frequencies of the indicated subsets are shown in pie charts. (E) Lung IL-18Rα⁺ ILCs were cultured without or with IL-18 cultured as in Fig. 4 D. The Thy1⁺NKp46⁻ cells were further analyzed for ST2 expression. The absolute numbers of the indicated subsets in each condition are shown in bar graphs. Data in A–C are representative of four or more independent experiments with four or more mice per group in each experiment, data in D are representative of ≥15 replicates per experimental group in two independent experiments, and data in E are representative of five or more replicates per experimental group in one experiment (mean ± SEM). *, P ≤ 0.05; **, P ≤ 0.01 by two-tailed Student’s t test. ns, not significant.