Phenotype analysis of CD133⁺ and Jurkat cells. Representative FACS histograms of CD133⁺ cells after 24-hour cytokine stimulation (A) and Jurkat cells (B) with antibodies (black peak) and relevant isotype controls (white peak). MFI ± SEM (n = 3) is shown for each antibody in the top right corner of the plot. CXCR4 surface expression was up-regulated on CD133⁺ cells after incubation with cytokines (from 15.1% ± 2.1% to 77.0 ± 3.6% CXCR4⁺, with MFI increasing from 234 ± 10.6 to 778 ± 127; n = 3). No significant alterations in 103B2 CD164 staining were observed before or after 24-hour cytokine stimulation (staining, 67% ± 4.5% to 69.4% ± 9.1%; MFI values, 1003 ± 121 to 1000 ± 246 (n = 3) for freshly isolated and 24-hour cytokine-stimulated cells, respectively). In separate dual-labeling experiments, 73.1% ± 6.4% of CD133⁺ cells coexpressed CXCR4 and the class II CD164 epitope on the surface after 24-hour cytokine stimulation (P = .41 for CXCR4 expression alone vs CXCR4 coexpression with CD164).