ALPs differentiate into EILPs. (A–C) 20,000 HSCs defined as CD150⁺ Flt3⁻ LSK cells and 30,000 ALPs isolated as GFP⁻ from Tcf7^EGFP/+ mice were injected into irradiated (150 rads) WT mice. Bone marrow cells were analyzed by flow cytometry after 7 d of reconstitution. (A) Lin⁻ Kit⁺ CD122^low bone marrow cells from an untreated Tcf7^EGFP/+ mouse, or WT mice injected with PBS, HSCs, or ALPs. (B) α4β7 expression on ALPs (gray), EILPs from a Tcf7^EGFP/+ mouse (black), and ALP-derived EILPs from A (red). (C) Quantification of EILPs recovered per mouse as shown in A. Data are representative of three independent experiments and are presented as mean ± SEM for n = 3 mice per group. (D) Flow cytometric analysis of IL-7Rα and YFP on the indicated bone marrow populations in an Il7r-Cre R26-stop-YFP Tcf7^EGFP/+ mouse. Lin⁻ Kit^high cells were used as a negative control for IL-7Rα expression (gray). Corresponding populations from a Tcf7^EGFP/+ mouse are used as a negative control for YFP expression (gray). Data are representative of three independent experiments. (E) GFP and YFP expression by IL-7Rα^low and IL-7Rα⁺ EILPs from an Il7r-Cre R26-stop-YFP Tcf7^EGFP/+ mouse as gated on the left histogram. (D and E) Numbers indicate the percentage of cells in each gate. (F) Flow cytometric analysis of bone marrow cells from Il7r^−/− mice and Il7r^+/+ littermates. Quantification of EILPs and ILC2ps defined as Lin⁻ Kit⁻ Sca-1⁺ CD25⁺ Thy1⁺ cells. (G) Quantification of ALP, EILP, and ILCp numbers in the bone marrow of Il2rg^−/− and Il2rg^+/+ littermates. (F and G) Data are representative of two independent experiments and are presented as mean ± SEM for n = 3 mice per group. A two-tailed unpaired Student’s t test was performed to determine significance. **, P < 0.01; ***, P < 0.005; nd, not detectable.