Distinct Transcriptional Programs Control Cross-Priming in Classical and Monocyte-Derived Dendritic Cells

Both classical DCs (cDCs) and monocyte-derived DCs (Mo-DCs) are capable of cross-priming CD8⁺ T cells in response to cell-associated antigens. We found that Ly-6C^hiTREML4^- monocytes can differentiate into Zbtb46⁺ Mo-DCs in response to granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) but that Ly-6C^hiTREML4⁺ monocytes were committed to differentiate into Ly-6C^loTREML4⁺ monocytes. Differentiation of Zbtb46⁺ Mo-DCs capable of efficient cross-priming required both GM-CSF and IL-4 and was accompanied by the induction of Batf3 and Irf4. However, monocytes require IRF4, but not BATF3, to differentiate into Zbtb46⁺ Mo-DCs capable of cross-priming CD8⁺ T cells. Instead, Irf4^-/- monocytes differentiate into macrophages in response to GM-CSF and IL-4. Thus, cDCs and Mo-DCs require distinct transcriptional programs of differentiation in acquiring the capacity to prime CD8⁺ T cells. These differences may be of consideration in the use of therapeutic DC vaccines based on Mo-DCs.