 pDCs that undergo malignant transformation cause a rare hematologic disorder, blastic plasmacytoid dendritic cell neoplasm.In the bone marrow, common dendritic cell progenitors expressing Flt3 (CD135) receptors are able to give rise to pDCs.Flt3 or CD135 signaling induces differentiation and proliferation of pDCs, although their mechanisms are not entirely understood.