Self-peptides with intermediate capacity to bind and stabilize MHC class I molecules may be immunogenic

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• Self-peptides presented by major histocompatibility complex class I (MHC-I) molecules are crucial for immune surveillance.
• Understanding self-peptide immunogenicity is key for developing effective cancer vaccines.

Purpose of the Study:

• To investigate the immunogenicity of MHC-I-binding self-peptides.
• To determine the relationship between peptide-MHC binding affinity and cytotoxic T lymphocyte (CTL) induction.
• To inform the design of self-peptide-based tumor vaccines.

Main Methods:

• Selection of 30 self-peptides based on predicted binding to H-2b molecules.
• Experimental validation of peptide binding using KD measurements and MHC-I stabilization assays.
• Immunization of mice (n=99) with individual peptides and assessment of peptide-specific CTL responses.

Main Results:

• A weak but significant correlation was observed between KD measurements and MHC-I stabilization.
• Twenty-eight peptides induced peptide-specific cytotoxic activity, with 84 mice developing significant CTL responses.
• Intermediate-affinity peptides elicited significantly higher CTL responses compared to high-affinity peptides (11/42 vs 1/21 mice, P < 0.05).

Conclusions:

• The study suggests a lack of tolerance to most MHC-I-restricted self-peptides.
• Strong anti-self immunity can be preferentially generated against self-peptides with intermediate MHC-I affinity.
• These findings have critical implications for the rational design of tumor vaccines utilizing MHC-I-binding self-peptides.