Single cell analysis reveals CD45RClow/-TNFR2+CD29lowCD8+ Tregs with superior activity

Although described in the 70's, CD8+ regulatory T cells (Tregs) remain incompletely understood and to date they remain poorly defined. The identification of reliable and consistent markers, as it was done for CD4+Tregs, remains an urgent task and a challenge. Herein, we analyzed total CD8+T cells using single cell CITEseq and VDJ TCR sequencing utilizing markers used previously to identify Tregs, in particular CD45RC dividing pro-inflammatory (CD45RChigh) and pro-regulatory (CD45RClow/-) CD8+T cells in rat, mice and human. 7000 freshly isolated, non-stimulated CD8+T lymphocytes of four healthy volunteers were analyzed. Combining at a single cell level transcriptome and protein expression data led for the first time to the characterization and definition of three subsets of regulatory CD8+T cells. Further in vitro functional analysis based on three markers highlighted the superior suppressive activity of the CD8+CD45RClow/-TNFR2+CD29low Tregs subset. To our knowledge, this is the largest characterization of human CD8+Tregs to date. This data resource will help improve our understanding of CD8+T cells heterogeneity and will help to translate CD8+Tregs to the clinic.