Figure 1.
In vitro and in vivo proliferation advantage of primary T-ALL cells expressing IL-7R induced by activated Notch1. (A) IL-7R and CD5 flow cytometry analysis of primary T-ALL cells (T-ALL5 and T-ALL8, from T-ALL patients 5 and 8, respectively) cocultured for 3 days onto OP9-GFP stromal cells supplemented with rhIL-7 and either a Notch activation inhibitor (red) or DMSO as vehicle (blue). Representative results from 3 experiments are shown. Shaded graphs represent background staining. (B) Percentages of primary human T-ALL cells expressing IL-7R cultured as in (A) for the indicated days. Mean ± standard error of the mean (SEM) of triplicates from a representative experiment are shown (n = 3). (C) Total numbers of primary T-ALL5 cells recovered at the indicated days from cocultures set up onto OP9-DL4 cells in the presence of rhIL-7 and either a neutralizing anti–IL-7Rα or an isotype-matched control antibody. Data are mean ± SEM (n = 3). (D) Flow cytometry of IL-7R+ (middle panel) and IL-7R−/lo (right panel) human primary T-ALL8 cells electronically gated as shown (left panel) upon labeling with CellTrace Violet and culture onto OP9-GFP cells supplemented with rhIL-7 for the indicated times. Data are representative of triplicate cultures from 2 independent experiments. (E) Relative proliferation of IL-7R+ vs IL-7R-/lo cells in (D), calculated as CellTrace Violet dilution ratio. (F) Proliferation potential of IL-7R+ and IL-7R−/lo T-ALL8 cells cultured onto OP9-GFP stromal cells supplemented with increasing concentrations of rhIL-7. Percentages of cells in the S+G2/M phases of the cell cycle were determined by Hoestch labeling and flow cytometry of cells electronically gated as in (D) after 3 days of culture. Data are mean ± SEM of triplicate cultures from 2 independent experiments. (G) IL-7R expression levels displayed by primary T-ALL cells from 3 patients analyzed by flow cytometry at the time of diagnosis (Patient) or after serial transplantation and thymus engraftment into consecutive Rag2−/−γc−/− immunodeficient mice (1st graft and 2nd graft). Numbers show percentages of positive cells. Shaded graphs show background staining with irrelevant isotype-matched antibodies. (H) Percentages of IL-7R–expressing T-ALL cells engrafting the indicated organs 10 to 12 weeks after transplant into immunodeficient mice in (G). Data are mean ± SEM of 3 to 7 mice. Percentages at the time of diagnosis (Patient) are shown for comparison. *P < .05, **P < .01, ***P < .001. ns, not significant.

In vitro and in vivo proliferation advantage of primary T-ALL cells expressing IL-7R induced by activated Notch1. (A) IL-7R and CD5 flow cytometry analysis of primary T-ALL cells (T-ALL5 and T-ALL8, from T-ALL patients 5 and 8, respectively) cocultured for 3 days onto OP9-GFP stromal cells supplemented with rhIL-7 and either a Notch activation inhibitor (red) or DMSO as vehicle (blue). Representative results from 3 experiments are shown. Shaded graphs represent background staining. (B) Percentages of primary human T-ALL cells expressing IL-7R cultured as in (A) for the indicated days. Mean ± standard error of the mean (SEM) of triplicates from a representative experiment are shown (n = 3). (C) Total numbers of primary T-ALL5 cells recovered at the indicated days from cocultures set up onto OP9-DL4 cells in the presence of rhIL-7 and either a neutralizing anti–IL-7Rα or an isotype-matched control antibody. Data are mean ± SEM (n = 3). (D) Flow cytometry of IL-7R+ (middle panel) and IL-7R−/lo (right panel) human primary T-ALL8 cells electronically gated as shown (left panel) upon labeling with CellTrace Violet and culture onto OP9-GFP cells supplemented with rhIL-7 for the indicated times. Data are representative of triplicate cultures from 2 independent experiments. (E) Relative proliferation of IL-7R+ vs IL-7R-/lo cells in (D), calculated as CellTrace Violet dilution ratio. (F) Proliferation potential of IL-7R+ and IL-7R−/lo T-ALL8 cells cultured onto OP9-GFP stromal cells supplemented with increasing concentrations of rhIL-7. Percentages of cells in the S+G2/M phases of the cell cycle were determined by Hoestch labeling and flow cytometry of cells electronically gated as in (D) after 3 days of culture. Data are mean ± SEM of triplicate cultures from 2 independent experiments. (G) IL-7R expression levels displayed by primary T-ALL cells from 3 patients analyzed by flow cytometry at the time of diagnosis (Patient) or after serial transplantation and thymus engraftment into consecutive Rag2−/−γc−/− immunodeficient mice (1st graft and 2nd graft). Numbers show percentages of positive cells. Shaded graphs show background staining with irrelevant isotype-matched antibodies. (H) Percentages of IL-7R–expressing T-ALL cells engrafting the indicated organs 10 to 12 weeks after transplant into immunodeficient mice in (G). Data are mean ± SEM of 3 to 7 mice. Percentages at the time of diagnosis (Patient) are shown for comparison. *P < .05, **P < .01, ***P < .001. ns, not significant.

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