T-ALL growth is independent of DCs in vivo and can be supported by other myeloid subsets. (A) Quantification of the indicated myeloid cell subsets in spleens of tumor-free WT and Flt3l^−/− mice. Bars represent means + standard error of the mean (SEM) of 3 independent experiments; circles represent individual mice. (B) Survival of WT and Flt3l^−/− recipient mice after transplantation with primary LN3 T-ALL cells. Graph displays cumulative survival of WT and Flt3l^−/− mice from 3 independent experiments, each using distinct primary T-ALL samples. The Kaplan-Meier survival curves were normalized to the first day of death in each experiment. The number (C) and frequency (D) of viable T-ALL cells from the spleens of Flt3l^−/− mice transplanted with primary LN3 T-ALL were assessed by flow cytometry 6 or 7 days after culture in the presence or absence of tumor-associated myeloid cells. Graphs display cumulative results from 4 independent experiments with distinct primary tumors. Circles represent the mean of 2 or 3 technical replicate wells per experiment. (E) Quantification of the frequencies of the indicated myeloid subsets within the splenic myeloid compartment of primary LN3 T-ALL-bearing WT and Flt3l^−/− mice. Bars represent means + SEM of cumulative data from 7 to 13 independent primary tumors; circles represent individual mice. *P < .05, **P < .01, ***P < .001, unpaired Student t test (A,E), log-rank test (B), and paired Student t test (C-D). ns, not significant.