Introduction: Although described in the 70’s, CD8+ regulatory T cells (Tregs) remains incompletely understood and to date, although several markers are used to define them, they remain inconsistent. The identification of good markers, as it was done for CD4+ Tregs; remains an urgent task and a challenge to advance our understanding.
Methods: Herein, we addressed the heterogeneity within total CD8+ T cells using single cell CITEseq and VDJ T cell receptor sequencing. We included markers used to previously identify Tregs, in particular CD45RC described by our team and others to divide effector (CD45RChigh) and pro-regulatory (CD45RClow/-) CD8+ T cells. 7K non-stimulated CD8+ T lymphocytes, including CD8+CD45RClow/- Tregs and CD8+CD45RChigh T cells of 4 healthy volunteers were analyzed.
Results: These analyses enabled the characterization of the transcriptomic heterogeneity at a single cell level from steady state total CD8+ T cells and allowed definition of regulatory CD8+CD45RClow/- Treg subsets. Functional analysis using cell sorting and suppressive assays highlighted the suppressive potential of the CD8+CD45RClow/-TNFR2+CD29low Tregs subset.
Conclusion: To date, to our knowledge, this is the largest characterization study of human CD8+ Tregs, this huge data resource will help in the current revival of CD8+ Tregs in research, will improve our understanding of T cell heterogeneity and will help translate CD8+ Tregs to the clinic.
