Expression of IL-2Rβ mRNA and protein by immature cells of the myeloid lineage. The appearance of Mac-1^loIL-2Rβ⁺ (A) and Mac-1^hiIL-2Rβ⁺ (B) bone marrow cells isolated by FACS. The identity of bone marrow cells expressing the gene encoding the β-chain of the IL-2R (C and D) was determined by hybridization in situ of ³⁵S-labeled probes synthesized in the antisense (C) or sense (D) orientation to cytocentrifuge preparations of total bone marrow from adult SCID mice. All cytocentrifuge preparations were fixed and stained with Wright-Giemsa stain before photomicroscopy. Magnification in A 800X and B through D 1000X. The results shown are representative of four independent experiments.