Mtb HLA-E-tetramer-sorted CD8+ T cells have a diverse TCR repertoire

Abstract

HLA-E molecules can present self- and pathogen-derived peptides to both natural killer (NK) cells and Tcells. Tcells that recognize HLA-E peptides via their Tcell receptor (TCR) are termed donor-unrestricted Tcells due to restricted allelic variation of HLA-E. The composition and repertoire of HLA-E TCRs is not known so far. We performed TCR sequencing on CD8+ Tcells from 21 individuals recognizing HLA-E tetramers (TMs) folded with two Mtb-HLA-E-restricted peptides. We sorted HLA-E Mtb TM+ and TM- CD8+ Tcells directly exvivo and performed bulk RNA-sequencing and single-cell TCR sequencing. The identified TCR repertoire was diverse and showed no conservation between and within individuals. TCRs selected from our single-cell TCR sequencing data could be activated upon HLA-E/peptide stimulation, although not robust, reflecting potentially weak interactions between HLA-E peptide complexes and TCRs. Thus, HLA-E-Mtb-specific Tcells have a highly diverse TCR repertoire.