Dendritic cells (DC) are crucial gatekeepers in regulating immunity. Whereas mature immunostimulatory myeloid DC (DC_ims) potently promote immune responses, IL‐10‐induced myeloid DC (DC‐IL‐10) counteract T cell activation. To elucidate the molecular repertoire by which DC‐IL‐10 secure reduced T cell activation, comparative gene expression profiling was done using Affymetrix U133A microarrays. Among the genes overexpressed in DC‐IL‐10, eight immunoreceptor tyrosine‐based inhibitory motif (ITIM)‐containing inhibitory molecules (ILT2, ILT3, ILT4, ILT5, DCIR, PILRA, FcγRIIB, SLAM) were found. Phenotypic analysis of DC‐IL‐10 defined an ILT^high DC subset further characterized by expression of CD14, TLR2, DC‐SIGN, and CD123 and the lack of lymphocyte, monocyte/macrophage, and plasmacytoid DC markers such as CD3, CD8, and CD68. A unique feature of the ILT^high DC subset was expression of the novel DC marker BDCA3, which was not detected on monocytes, immature DC, DC_ims, or ILT^low DC‐IL‐10. While the allogeneic T cell proliferation induced by the entire DC‐IL‐10 population was approximately 30% of that stimulated by DC_ims, allogeneic MLR responses driven by the ILT^high DC subset were reduced to 8% of the allostimulatory capacity of DC_ims, although secretion of the inhibitory cytokine IL‐10 and other Th1/Th2‐associated cytokines was similar in these cells.