Bifurcated dendritic cell differentiation in vitro from murine lineage phenotype-negative c-kit+ bone marrow hematopoietic progenitor cells

We have recently established the culture system to generate dendritic cells (DCs) from murine Lin(-)c-kit(+) bone marrow hematopoietic progenitor cells (HPCs) in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF) + stem cell factor (SCF) + tumor necrosis factor-alpha (TNF-alpha). We present here the identification of two DC precursor subsets originated from HPCs with the phenotype of CD11b(-/dull)CD11c(+) and CD11b(+hi)CD11c(+) that develop independently at early time paints (days 4 to 6) in the same culture conditions. Both of CD11b(-/dull)CD11c(+) and CD11b(+hi)CD11c(+) precursors could differentiate at day 10 to 14 into CD11b(-/dull)CD11c(+) mature DCs with typical morphology, phenotype, and the ability to stimulate allogenic mixed leukocyte reaction (MLR). However, the endocytic capacity of fluorescein isothiocyanate dextran was markedly reduced during the differentiation. CD11b(-/dull)CD11c(+) precursors expressed high levels of Ia, CD86, CD40, and E-cadherin molecules, but not c-fms transcript, and mature DCs derived from this precursor subset continue to express abundant E-cadherin antigen, a discernible marker for Langerhans cells. In contrast, CD11b(+hi)CD11c(+) precursors expressed c-fms mRNA, but low levels of Ia, CD86, and E-cadherin, whereas CD40 was undetectable. CD11b(-/dull)CD11c(+) mature DCs differentiated from these precursors displayed abundant c-fms mRNA and nonspecific esterase activity. Interestingly, CD11b(+hi)CD11c(+) precursors, but not CD11b(-/dull)CD11c(+) precursors, may be bipotent cells that can be induced by M-CSF to differentiate into macrophages. All of these results suggest that CD11b(-/dull)CD11c(+) and CD11b(+hi)CD11c(+) cells are distinct DC precursors derived from Lin(-)c-kit(+) HPCs, which differentiate into mature DCs through bifurcated and independent DC differentiation pathways. (C) 1998 by The American Society of Hematology.