Expression of miR-155, SHIP1, and sensitivity to anti-µ in subpopulations of CLL cells isolated from the blood mononuclear cells of the same patient. (A) Flow cytometric analyses of representative unsorted CLL cells (left), isolated CD5^brightCXCR4^dim CLL cells (upper right), or isolated CD5^dimCXCR4^bright CLL cells (lower right). Contour plots (10% probability) depict the fluorescence of CLL cells stained with fluorochrome-conjugated mononuclear antibodies specific for human CD5 (y-axis) or human CXCR4 (x-axis). (B) Expression of miR-155 in CLL cells that expressed high levels of CD5 and low levels of CXCR4, or low levels of CD5 and high levels of CXCR4. The height of each column in the histogram indicates the fold increase of miR-155 copy number of sorted CD5^brightCXCR4^dim cells relative to that of sorted CD5^dimCXCR4^bright cells, as indicated at the bottom. Statistical significance was determined by paired Student t test (P < .05). (C) Expression of SHIP1 in sorted CD5^brightCXCR4^dim or CD5^dimCXCR4^bright CLL cells of representative samples (CLL1 [left 2 lanes] or CLL2 [right 2 lanes]), as indicated at the bottom. Probing for β-actin was used to monitor for equal loading of sample lysates. (D) Anti-µ–induced calcium mobilization in CLL cells that expressed high levels of CD5 and low levels of CXCR4, or low levels of CD5 and high levels of CXCR4. The relative mean fluorescence intensity in intracellular calcium is plotted in Figure 3B,C for each cell subset. The height of each column in the histogram on the right corresponds to the increase of fluorescence intensity after anti-µ stimulation for sorted CD5^brightCXCR4^dim or CD5^dimCXCR4^bright cells, as indicated at the bottom. Statistical significance was determined by unpaired Student t test (P < .05).