Surface marker expression pattern and gene expression profile of human CD34⁺CD1a⁻BMPRIA⁺ intrathymic precursors. (A) Purified thymic CD34⁺CD1a⁻ cells were stained with anti-BMPRIA Abs and a range of mAbs against differentiation-specific antigens, and then they were analyzed by flow cytometry. Solid histograms represent the expression of the indicated cell surface markers on CD34⁺CD1a⁻BMPRIA⁻ and CD34⁺CD1a⁻BMPRIA⁺ cell subsets. Open histograms represent background fluorescence using isotype-matched irrelevant mAbs. Similar staining patterns were obtained in 5 different experiments. (B) Gene expression in sorted CD34⁺CD1a⁻BMPRIA⁺ thymic precursors. Transcription levels of different genes were normalized for GNB2L1 mRNA content and are shown relative to GNB2L1-normalized transcription in the CD34⁺CD1a⁻BMPRIA⁻ cell subset. (C) Percentage of BMPRIA⁺ cells in CD34^loCD44^hiCD5^lo/− and CD34^loCD44^loCD5⁺ thymic precursor subpopulations. Horizontal bar represents the mean of 7 independent experiments (*P ≤ .05 by t test).