Il1rap is dispensable for normal HSC function. (A-D) IL1RAP expression on myeloid progenitor populations (CMP, common myeloid progenitor; LSK, lineage negative, Sca1 positive, c-kit positive cells; MEP, megakaryocyte erythrocyte progenitor) and stem and multipotent progenitor populations (ltHSC, long-term HSC; MPP, multipotent progenitor; stHSC, short-term HSC). Histograms display the stains from 1 representative sample, and diagrams summarize the data (n = 3). Stained BM cells from an Il1rap^−/− mouse were used as negative controls. (E) Numbers of PB myeloid cells in Il1rap^+/+ and Il1rap^−/− mice. (F) Levels of CD11b⁺ cells in PB, normalized to mean of Il1rap^+/+ mice. The P value was calculated by a 1-sided Student t test to confirm the data presented in panel E. (G) Relative size of the GMP population among myeloid progenitors, normalized to the mean of the Il1rap^+/+ mice. (H) Proportion of CD11b⁺ BM cells in Il1rap^+/+ and Il1rap^−/− mice. (I-J) Donor reconstitution in PB and lineage distribution within the donor cell population 16 weeks after competitive BM transplantations of Il1rap^+/+ and Il1rap^−/− cells. (K-L) Donor reconstitution and lineage distribution within the donor population 10 weeks after transplantation of BM into secondary recipient mice.