Research Information System
FRONTIERS IN IMMUNOLOGY, vol.15, 2024 (SCI-Expanded)
The expression levels of TCRs on the surface of human T cells define the avidity of TCR-HLA/peptide interactions. In this study, we have explored which components of the TCR-CD3 complex are involved in determining the surface expression levels of TCRs in primary human T cells. The results show that there is a surplus of endogenous TCR alpha/beta chains that can be mobilised by providing T cells with additional CD3 gamma,delta,epsilon,zeta chains, which leads to a 5-fold increase in TCR alpha/beta surface expression. The analysis of individual CD3 chains revealed that provision of additional zeta chain alone was sufficient to achieve a 3-fold increase in endogenous TCR expression. Similarly, CD3 zeta also limits the expression levels of exogenous TCRs transduced into primary human T cells. Interestingly, transduction with TCR plus CD3 zeta not only increased surface expression of the introduced TCR, but it also reduced mispairing with endogenous TCR chains, resulting in improved antigen-specific function. TCR reconstitution experiments in HEK293T cells that do not express endogenous TCR or CD3 showed that TCR alpha/beta and all four CD3 chains were required for optimal surface expression, while in the absence of CD3 zeta the TCR expression was reduced by 50%. Together, the data show that CD3 zeta is a key regulator of TCR expression levels in human T cells, and that gene transfer of exogenous TCR plus CD3 zeta improved TCR surface expression, reduced TCR mispairing and increased antigen-specific function.