Going Pro to enhance T-cell immunogenicity: easy as π?

Area of Science:

• Immunology
• Structural Biology
• Computational Chemistry

Background:

• MHC class I molecules present intracellular peptides to CD8(+) T cells for immune surveillance.
• High-affinity peptide-MHC (pMHC) interactions are crucial for effective CD8(+) T-cell responses.
• Current methods to enhance pMHC affinity often reduce T-cell recognition, limiting therapeutic potential.

Purpose of the Study:

• To investigate a novel peptide modification strategy to enhance pMHC affinity and stability.
• To determine if enhanced pMHC binding can improve T-cell receptor recognition.
• To elucidate the structural basis of improved pMHC interactions.

Main Methods:

• Peptide modification: substitution of the third residue with proline (p3P).
• Biophysical assays to measure pMHC affinity and complex stability.
• X-ray crystallography to determine the structural basis of pMHC interactions.
• T-cell activation assays to assess recognition.

Main Results:

• The p3P modification significantly increased pMHC affinity and complex stability.
• Enhanced pMHC binding did not compromise, but rather improved, T-cell receptor recognition.
• X-ray crystallography revealed novel CH-π bonding between p3P and MHC residue Y159, contributing to stability.

Conclusions:

• Substitution of the third residue with proline is a viable strategy to enhance pMHC stability and affinity.
• CH-π bonding plays a significant role in stabilizing pMHC complexes.
• This approach offers a promising method for improving cancer immunotherapies by enhancing pMHC interactions without sacrificing T-cell recognition.