High-affinity TCRs generated by phage display provide CD4+ T cells with the ability to recognize and kill tumor cell...

Area of Science:

• Immunology
• Cancer Immunology
• T cell biology

Background:

• T cell receptors (TCRs) mediate antigen recognition crucial for adaptive immunity.
• Engineering T cells with specific TCRs is a promising cancer immunotherapy strategy.
• The affinity of TCRs for their cognate antigen influences T cell function and specificity.

Purpose of the Study:

• To investigate the impact of varying T cell receptor (TCR) affinities on the specificity and activity of engineered human T cells.
• To evaluate the recognition of the cancer/testis antigen NY-ESO-1 by T cells expressing different 1G4 TCR variants.

Main Methods:

• Bacteriophage display was used to generate 1G4 TCR variants with a range of affinities.
• Human T cells were engineered to express these 1G4 TCR variants.
• T cell binding and specificity were assessed using NY-ESO-1/HLA-A2 tetramer assays and tumor cell line recognition assays.
• The role of CD8 co-receptor in TCR-mediated recognition was examined.

Main Results:

• Engineered T cells expressing intermediate- and high-affinity TCRs showed high avidity and antigen specificity.
• Increased TCR affinity led to a loss of target cell specificity in CD8(+) T cells.
• The highest affinity TCR (26 pM K(D)) resulted in complete loss of antigen specificity.
• Mid-range affinity TCRs (5 and 85 nM K(D)) required CD8 blockade for specificity.
• Lower affinity TCRs (450 nM and 4 microM K(D)) demonstrated antigen-specific recognition.
• Low-affinity TCRs significantly increased CD4(+) T cell reactivity against tumor cell lines.

Conclusions:

• TCR affinity is a critical determinant of engineered T cell specificity and function.
• High-affinity TCRs do not necessarily translate to improved therapeutic efficacy due to potential off-target effects.
• Lower affinity TCR variants may offer a strategy to enhance CD4(+) T cell-mediated anti-tumor immunity.