A distinct lineage of origin reveals heterogeneity of plasmacytoid dendritic cells III

Plasmacytoid dendritic cells (pDCs) are an immune subset devoted to the production of high amounts of type 1 interferons in response to viral infections. While conventional dendritic cells (cDCs) originate mostly from a common dendritic cell progenitor (CDP), pDCs have been shown to develop from both CDPs and common lymphoid progenitors (CLP). Here we found that pDCs developed predominantly from IL7R+ lymphoid progenitor cells. Expression of SiglecH and Ly6D defined pDC lineage commitment along the lymphoid branch. Transcriptional characterization of SiglecH+Ly6D+ precursors indicated that pDC development requires high expression of the transcription factor IRF8, while pDC identity relies on TCF4. RNA sequencing of IL7R+ lymphoid and CDP-derived pDCs mirrored the heterogeneity of mature pDCs observed by single-cell analysis. Both mature pDC subsets are able to secrete type 1 interferons, but only myeloid-derived pDCs share with cDCs their ability to process and present antigen. Overall design: Bulk RNA Seq was performed from sort purified DN, SP and DP lymphoid progenitors and BM pDCs of 4 individual mice