RNA-seq analysis of activated plasmacytoid dendritic cell subsets after viral infection

Hematopoiesis generates cell diversity through evolutionarily-determined differentiation programs defined at steady-state conditions. Here, we show that peripheral innate immune activation can generate cell diversity and functional specialization during the activation process. We found that activation of steady state human plasmacytoid pre-dendritic cells (pDCs) with a single microbial stimulus induced their differentiation into three phenotypically, morphologically, and functionally distinct subsets, in the absence of cell division: P1 (PD-L1+CD80-), P2 (PD-L1+CD80+) and P3 (PD-L1-CD80+). Different stimuli induced variable proportions of the subsets, suggesting that steady state pDC are multipotent. P1-pDCs display a plasmacytoid morphology and strong specialization on IFN production, whereas P3-pDCs adopt a dendritic morphology and adaptive immune functions. P2-pDCs have an intermediate functional profile. We found that a P1-pDC phenotype is present in human autoimmune diseases associated to type I IFN production as lupus and psoriasis, supporting their pathophysiological relevance. We propose that peripheral innate activation represents a differentiation mechanism to generate subsets diversity and functional complementarity in human pDCs. Overall design: 15 samples: medium (control condition), ex-vivo, P1, P2 and P3, each from 3 healthy donors. Ex-vivo plasmacytoid dendritic cells from the blood of healthy human donors were treated for 24h with influenza virus. Treated cells were sorted as P1, P2, and P3 subsets depending on surface markers: P1 (PD-L1+CD80-), P2 (PD-L1+CD80+) and P3 (PD-L1-CD80+). Non-treated control cells correspond to pDCs kept in medium.