Tumor-associated (Tu) macrophages and monocytes from the CNS leukemia microenvironment support T-ALL survival. (A) Quantification of viable CNS T-ALL cells cultured for 6 to 7 days in the presence or absence of healthy (WT) or tumor-associated (Tu) microglia or nonmicroglia myeloid cells from the CNS, respectively, as assessed by flow cytometry. Data are compiled from 13 independent experiments using distinct color-coded primary LMO2 tumor stocks engrafted into F1 littermate mice. Each circle represents the average of duplicate or triplicate wells. Data are normalized to wells of “T-ALL” alone; bars represent mean + SEM from 13 independent experiments. Data are shown with all combined T-ALL samples (left) or stratified by Hhex^high (middle) and Hhex^low (right) subtypes. (B-C) Quantification of viable CNS-isolated T-ALL cells cultured for 6 to 7 days in the presence or absence of the indicated FACS-purified myeloid subsets from the CNS, as assessed by flow cytometry. Data are compiled from 12 (B) and 3 independent experiments (C) using distinct color-coded primary LMO2 T-ALL stocks injected into F1 littermates. Each circle represents the average of duplicate or triplicate wells. Data are normalized to T-ALL alone; bars represent mean + SEM. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001 (using the unpaired Student t test [Mann-Whitney U] in panel A or nonparametric Kruskal-Wallis test in panels B-C). WT, wild-type.