Functional signaling and targeting of IL-7Rp in normal and malignant thymocytes. (A) Independent human thymi (n = 2) were cultured for 15 minutes in a complete medium deprived of IL-7 (basal state), supplemented with IL-7 (100 ng/mL) (IL-7), or supplemented with IL-7 and ruxolitinib (500 nM; IL-7+ruxolitinib). pSTAT5 Y694 was then assessed by FC for each condition and each subpopulation (histograms). Data are presented according to subsetting into thymocytic subpopulations. DN, double negative; DP, double positive; ISP, immature simple positive; SP, single positive. (B) sIL-7R expression (%CD127⁺ blasts) on PDXs (n = 46) used in the experiments. Samples are color-coded per the category of the T-ALL from which they are derived. (C) PDX cells were cultured as described for panel A before being subjected to pSTAT5 Y694 analysis by FC. Dot plots represent pSTAT5 median of fluorescence intensity for each case and each condition. Mean and SEM are represented. Friedman test with post hoc Dunn multiple comparisons. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. (D) PDX cells were cultured for 24 hours in complete medium deprived of IL-7, supplemented with IL-7 (100 ng/mL), or supplemented with IL-7 and ruxolitinib (1 μM) before the RNA extraction and quantification of CISH (left) and PIM1 (right) by qRT-PCR. Mean and SEM are represented. Friedman test with post hoc Dunn multiple comparisons. ns, not significant; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001.