Identification Of Dendritic Cell Precursors In The Culture Of Bone Marrow With Hematopoietic Cytokines

Abstract Dendritic cells (DCs) play crucial parts in a variety of immune responses by capturing and presenting antigens to naïve T cells and by producing the subsequent T-cell activation or tolerance. In vitro culture systems of DCs have been widely used. The culture of bone marrow (BM) in the presence of a hematopoietic cytokine, Fms-like tyrosine kinase 3 ligand (FLT3L), produces plasmacytoid DCs (pDCs) and classical DCs (cDCs), whereas the culture of BM with granulocyte-macrophage colony-stimulating factor (GM-CSF) generates DCs and macrophages considered to possess inflammatory phenotypes. In the present study, we examined the culture of BM with both cytokines, i.e., FLT3L and GM-CSF in combination and identified 4 different subsets in CD11c⁺ MHCII+ cells. Meanwhile, in the culture of BM with FLT3L, we discovered a novel population of CD11c⁺ MHCIIhi cells that possess a limited capacity of antigen-presenting activity, suggesting precursors for DCs. This novel population of DC precursors from the BM culture with FLT3L was isolated and evaluated for their potential to differentiate to DCs in the BM culture containing both FLT3L and GM-CSF. Consequently, we demonstrated that the presence of a novel population of DC precursors in the in vitro culture system of DCs.