Fig. 1: Transmembrane FLT3L drives human DC differentiation in vitro.

a Expression of membrane-bound FLT3L in mouse bone marrow-derived stromal cells engineered to express human FLT3L (MS5_F) and control (MS5_CTRL). b Human cDC subsets differentiated in vitro from CD34⁺ cord blood-derived HSPCs cultured with MS5 expressing membrane-bound FLT3L (MS5_F) or MS5 supplemented with recombinant human FLT3L (MS5+recFL) at day 15 (n = 3 donors in one experiment). *p < 0.05, **p < 0.01, ***p < 0.001, one-way ANOVA test with Tukey’s multiple comparisons. c Representative flow cytometry plots and quantification of human cDC subsets differentiated in vitro from cord blood-derived CD34⁺ progenitors in culture with mouse stromal cell lines MS5 and OP9 expressing human FLT3L (MS5_F and OP9_F) at day 15 (n = 4 donors in one experiment). *p < 0.05, one-way ANOVA test with Tukey’s multiple comparisons). d Absolute number and frequency of CD141⁺Clec9A⁺ and CD14⁻CD1c⁺ human cDCs differentiated from CD34⁺ HSPCs in direct contact (lower well) or physically separated (upper well) from engineered MS5_F. DC differentiation was assessed at day 15 by flow cytometry (n = 6 donors in three independent experiments). *p < 0.05, two-tailed paired Student’s t-test. Data are presented as floating bars ranging from min to max and line represents median (b–d).