BioProject

XCR1+ dendritic cells (DC) have been shown to excel in antigen cross-presentation for the activation of naïve CD8 T cells. More...

XCR1+ dendritic cells (DC) have been shown to excel in antigen cross-presentation for the activation of naïve CD8 T cells. This property was reported to be associated to the subset of the XCR1+ DC expressing IL-12b upon ex vivo stimulation for 24 h with a mixture of CpG, IFN-γ, and GM-CSF (Lin ML et al. Proc Natl Acad Sci USA. 2008. PMID: 18272486). DC found in the steady-state non-lymphoid tissues undergo an homeostatic, tolerogenic, maturation and migrate to the draining lymph nodes to interact with naive autoreactive T cells and induction their peripheral tolerance. In contrast, spleen DC are thought to exist solely in an immature state. The aim of this study was to re-examine heterogeneity within steady state spleen XCR1+ DC, in particular examining whether this population encompass a fraction of mature DCs as assessed through their expression of CCR7 and/or the Il12b gene. Indeed, we show that a small fraction of XCR1+ spleen DC constitutively mature into two distinct but likely successive activation stages characterized as CCR7+ and CCR7+Il12b+ respectively, and correlated with increasing ability to cross-present antigen to naïve CD8 T cells. Transcriptomic analysis of the subsets of XCR1+ DC found in steady state spleen unexpectedly showed that their homeostatic maturation was unexpectedly associated with up-regulated of many genes thought to drive pro-inflammatory T-cell responses and previously found to be commonly induced upon maturation of distinct DC subsets in response to stimulation by various microbial-type stimuli (Vu Manh TP et al. Eur J Immunol. 2013. PMID: 23553052). Thus, our results reveal that spleen XCR1+ DC undergo constitutive maturation and emphasize the common mechanisms operating upon homeostatic, tolerogenic, DC maturation versus microbial-type stimuli-induced, immunogenic, DC maturation. Overall design: DC were isolated from the spleen of untreated Il12b-EYFP reporter mice (Reinhardt RL et al. J Immunol. 2006. PMID:16849470) mice as previously described (Robbins SH et al. Genome Biol. 2008. PMID: 18218067; Baranek T et al. Cell Host Microbe. 2012. PMID: 23084923). DC subsets were sorted by flow cytometry according to the marker combinations described in the “characteristics: phenotype” field for each sample. Less...