A platform for mapping reactive cysteines within the immunopeptidome.

Area of Science:

• Immunology
• Proteomics
• Chemical Biology

Background:

• Major histocompatibility complex class I (MHC-I) antigen presentation is crucial for immune responses.
• Cysteines in the immunopeptidome offer therapeutic targets, particularly for generating neoepitopes via covalent ligands.
• Understanding cysteine reactivity on MHC-I-bound peptides is key for developing novel immunotherapies.

Purpose of the Study:

• To develop a platform for mapping reactive cysteines on MHC-I-bound peptide antigens.
• To investigate the impact of immune stimulation on cysteine reactivity within the MHC-I-bound peptidome.
• To explore the therapeutic potential of targeting these reactive cysteines for immunotherapy.

Main Methods:

• Development of cell-impermeable sulfonated maleimide probes for capturing reactive cysteines.
• Application of these probes in chemoproteomic experiments to analyze MHC-I-bound peptides.
• Assessment of antibody-dependent cellular phagocytosis induction using targeted maleimide conjugates.

Main Results:

• Reactive cysteines on MHC-I-bound antigens display varying reactivity levels.
• Interferon-gamma stimulation significantly enhances the reactivity of cysteines at position 8 of 9-mer MHC-I peptides.
• Targeting reactive cysteines with a maleimide-conjugated peptide induced antibody-dependent cellular phagocytosis.

Conclusions:

• The developed platform effectively maps reactive cysteines on MHC-I-bound antigens.
• Immune stimulation modulates cysteine reactivity, offering specific targets for therapeutic intervention.
• Targeting reactive cysteines on MHC-I peptides represents a promising strategy for enhancing cellular immunity.