Thedendriticcellsystemcontainsconventionaldendriticcells(DCs)andplasmacytoidpre-dendriticcells(pDCs).BothDCsandpDCsarebonemarrowderivedcells.AlthoughthecommonfunctionsofDCsareantigen-processingandT-lymphocyteactivation,theydifferinsurfacemarkers,migratorypatterns,andcytokineoutput.ThesedifferencescandeterminethefateoftheTcellstheyactivate.SeveralsubsetsofmatureDCshavebeendescribedinbothmouseandhumanandthedevelopmentalprocessesofthesespecializedDCsubsetshavebeenstudiedextensively.TheoriginalconceptthatallDCswereofmyeloidoriginwasquestionedbyseveralrecentstudies,whichdemonstratedthatinadditiontotheDCsderivedfrommyeloidprecursors,someDCscouldalsobeefficientlygeneratedfromlymphoid-restrictedprecursors.Moreover,ithasbeenshownrecentlythatbothconventionalDCsandpDCscanbegeneratedbytheFlt3expressinghemopoieticprogenitorsregardlessoftheirmyeloid-orlymphoid-origin.ThesefindingssuggestanearlydevelopmentalflexibilityofprecursorsforDCsandpDCs.ThisreviewsummarizessomerecentobservationsonthedevelopmentofDCsysteminbothhumanandmouse.
