Increasing Functional Avidity of T Cell Receptor (TCR)-Redirected T Cells by Removing Defined N-Glycoslyation Sites in the Constant Domain of Introduced TCR Chains.

Abstract

Adoptive transfer of T lymphocytes transduced with a TCR to impart tumor reactivity has been reported as potential strategy to redirect immune responses to target cancer cells. However, the affinities of most TCRs specific for shared tumor antigens that can be isolated are usually low, in part reflecting the nature of the targeted tumor antigens which are self-proteins. Thus strategies that can increase the affinity or functional avidity of TCRs to be used in therapy to transduce T cells might be therapeutically beneficial. However, current strategies for increasing TCR affinity require extensive and usually random mutagenesis followed by screening the many derived mutations, and must be individualized for each TCR. Since glycosylation impacts the flexibility, movement, and interactions of surface molecules, we tested if removing conserved N-glycoslyation sites in the constant regions of TCR a or b chains can increase the functional avidity of T cells transduced with such modified TCR. We observed enhanced functional avidity and improved recognition of tumor cells by CD8 T cells harboring partially N-deglycosylated as compared to wild type (wt) TCR chains. T cells transduced with wt or N-deglycosylated TCR chains bound tetramer equivalently at 4°C, but tetramer-binding was enhanced at 37°C, reflecting predominantly reduced tetramer dissociation, suggesting an energy-dependent conformational change and/or enhanced clustering of N-deglycosylated TCR chains. The enhanced avidity was evident in the presence or absence of the CD8 co-receptor. This strategy was effective with murine and human TCRs specific for different antigens, and thus should be readily translated to TCRs with any specificity. Thus, transfer of partially deglycosylated TCR chains is a generally applicable strategy that can be used to increase functional avidity of TCR-transduced T cells.