Phenotype and functional identity of GM-CSF-independent dendritic cells generated by long-term propagation of DC progenitor cells in bone marrow cells and skin Langerhans cells.

Evidence is provided that dendritic cells (DC) generated by either long-term bone marrow cell (BMC) culture with Flt3L and interleukin-6 (IL-6), or after short-term BMC culture with granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), contain heterogeneous cell populations of admixed DC and Mphi, regardless of the cytokine source. By employing GM-CSF-independent culture systems with the aid of Flt3/Flk-2 ligand and IL-6 and phenotypic characterization of BMC-derived DC and skin Langerhans cells (LC), revealed similar phenotypes. Furthermore, CD103 (OX62), which is widely used for rat DC separation, was found to be insufficient to enrich DC, due to downregulation of the marker. In this regard, the most efficient selection of rat DC, was obtained by CD161a (NKR-P1A), a member of the C-type lectin family. Despite the phenotypic similarity with BMC-derived DC, the nucleus of LC showed a distinct morphology. A large population of DC generated by Flt3L/IL-6 from GM-CSF receptor-deficient mice by do not express NK1.1 (NKR-P1B and NKR-P1C). The profiles for BMC-derived DC were the same as for skin Langerhans cells.