CD4⁺ and CD8⁺ TCRβ repertoires possess different potentials to generate extraordinarily high-avidity T cells

Recent high throughput sequencing analysis has revealed that the TCRβ repertoire is largely different between CD8⁺ and CD4⁺ T cells. Here, we show that the transduction of SIG35α, the public chain-centric HLA-A∗02:01(A2)/MART1 27-35 TCRα hemichain, conferred A2/MART1 27-35 reactivity to a substantial subset of both CD8⁺ and CD4⁺ T cells regardless of their HLA-A2 positivity. T cells individually reconstituted with SIG35α and different A2/MART1 27-35 TCRβ genes isolated from CD4⁺ or CD8⁺ T cells exhibited a wide range of avidity. Surprisingly, approximately half of the A2/MART1 27-35 TCRs derived from CD4⁺ T cells, but none from CD8⁺ T cells, were stained by A2/MART1 27-35 monomer and possessed broader cross-reactivity. Our results suggest that the differences in the primary structure of peripheral CD4⁺ and CD8⁺ TCRβ repertoire indeed result in the differences in their ability to form extraordinarily high avidity T cells which would otherwise have been deleted by central tolerance.