We investigated whether the expression of CD11b on precursors derived in vitro from CD34 + hematopoietic stem cells was related to their ability to generate CD11b − and CD11b + Langerhans dendritic cells (LC).Human CD34 + cells purified from cord blood were cultured with FLT3 ligand, thrombopoietin, and stem cell factor (FTS) for 2 weeks, analyzed, and sorted by FACS. Sorted fractions were cultured as above, or differentiated into LC with GM-CSF, IL-4, and TGF-β1 (G4-TGF) for 6 days. The capacity of LC to internalize langerin and dextran was assessed.Ex vivo, human CD34 + cells were CD11b − and mostly CLA + . After 2 weeks of culture with FTS, CD34 − CLA − CD11b − and CD34 − CLA − CD11b + cells emerged. CD11b − cells were the most ancestral because they were the only ones to proliferate with FTS, and constantly generated CD11b + cells. Both CD11b − and CD11b + sorted cells generated E-cadherin + langerin + LC after incubation with G4-TGF. The former fraction contained 46% ± 15% of E-cadherin + and 10% ± 5% of langerin + cells, whereas in the latter fraction these values reached respectively 66% ± 23% and 30% ± 16% (mean ± SD, n = 7, p < 0.056). Looking at functional properties, CD11b − and CD11b + LC were similar in terms of langerin and dextran endocytosis. By contrast, only CD11b + LC internalized fluorescent LPS.Human CD34 + CD11b − cells differentiate in FTS culture into a CD34 − CD11b − precursor that in turn generates CD34 − CD11b + cells. These cells are enriched in LC precursors compared to CD34 − CD11b − cells. Both CD11b − and CD11b + LC are generated in vitro, and each fraction may assume different functions in inflammatory situations.