Two functionally distinct myeloid dendritic cell subpopulations are present in bovine blood

•Phenotypically distinct CD205Hi and CD205Lo myeloid DC subpopulations are present in bovine blood.•CD205Hi and CD205Lo myeloid DCs have an equal capacity to acquire antigen.•CD205Lo but not CD205Hi myeloid DCs efficiently activate T cell.•CD205Lo and CD205Hi myeloid DCs may represent developmentally distinct DC lineages. Immature myeloid (m)DCs circulating in the blood of cattle have been defined as lineage negative (Lin−)MHCII+CD11c+CD205+ cells. Lin−MHCII+CD11c+CD205+ mDCs (0.2% blood mononuclear cells) isolated from bovine blood were heterogeneous in cell size and CD205 expression. Using highspeed cell sorting, Lin−MHCII+CD11c+CD205+ DCs were sorted into CD205Hi and CD205Lo subpopulations which were phenotypically distinct and differed significantly (P