CD70TG mice lack EoPs and CD70TG GMPs are unable to generate eosinophils. (A) Representative contour plot of staining for CMPs (CD16/32^intCD34⁺) and GMPs (CD16/32^hiCD34⁺) within the Lin⁻c-Kit⁺ compartment in bone marrow of WT and CD70TG mice (percentages are shown). (B) Absolute numbers of CMPs and GMPs present in 2 femurs and 2 tibiae per mouse. (C) Representative contour plot of staining for EoPs (c-Kit^lowIL-5Rα⁺) within the Lineage⁻CD34⁺CD16/32^hi compartment of WT and CD70TG mice (percentages are shown). (D) Absolute numbers of EoPs. (E) Amount of mRNA of GATA1, C/EBPϵ, and C/EBPα relative to 18S in GMPs and EoPs from WT and CD70TG mice. (F) When CMPs or GMPs (left) are sorted and cultured for 9 days with SCF and IL-5, they develop into a near homogeneous population of eosinophils, as determined by May-Grunwald Giemsa staining on cytospins (middle) and flow cytometric analysis for expression of Siglec-F, F4/80, and Gr1 (right). Filled histogram shows fluorescence-minus-one control staining. (G) Absolute number of eosinophils derived from 1.0 × 10⁴ CMPs or GMPs from WT and CD70TG mice cultured for 9 days with SCF and IL-5. (H) Absolute number of cells derived from 2.5 × 10³ CMPs or GMPs from WT and CD70TG mice cultured for 9 days with SCF, IL-5, and GM-CSF. Data are mean ± SD for 3 individual mice per group (B,D) and for 2 or 3 mice (E). (G-H) Data are mean ± SD for 2 cultures per condition. (B,D,G) Data are representative of 3 independent experiments. (H) Data are representative of 2 independent experiments. *P < .05; **P < .01.