Gene expression of CD34⁺CD1a^– and CD34⁺CD1a⁺ thymocytes. Expression levels (in arbitrary fluorescence units) of several genes were extracted from previously performed Affymetrix microarrays.¹³  (A) “Stem cell–like” genes, (B) T-cell–specific genes, (C) “non-T lineage” genes. (D) RQ-PCR validation: fold increase or decrease in expression between CD34⁺CD1a^– and CD34⁺CD1a⁺ subsets. (E) Expression patterns of CD133, MPO, and CD13/CD33 were validated at the protein level using flow cytometry. CD34⁺ cells from thymus and UCB were purified using AutoMACS and gated for the indicated populations. Expression of CD13/33 in mature granulocytes was at least 10-fold higher than in CD34⁺ UCB cells.