Activation of Human CD8+ T Cells with Nitroso Dapsone-Modified HLA-B*13:01-Binding Peptides

Area of Science:

• Immunology
• Pharmacology
• Human Genetics

Background:

• Drug metabolites can covalently bind proteins, activating T cells.
• The specific antigenic determinants and drug metabolite presence in T cell stimulatory peptides remain unclear.
• Susceptibility to dapsone hypersensitivity is linked to HLA-B*13:01 expression.

Purpose of the Study:

• To design and synthesize nitroso dapsone-modified peptides that bind to HLA-B*13:01.
• To investigate the immunogenicity of these modified peptides using T cells from hypersensitive patients.
• To characterize the T cell response and its HLA restriction.

Main Methods:

• Designed cysteine-containing peptides with high HLA-B*13:01 binding affinity.
• Modified peptides with nitroso dapsone at the cysteine residue.
• Generated and characterized CD8+ T cell clones, assessing proliferation and effector molecule secretion.
• Utilized autologous antigen-presenting cells (APCs) and C1R cells expressing HLA-B*13:01 for HLA restriction analysis.
• Confirmed modification site and purity using mass spectrometry.

Main Results:

• Generated HLA-B*13:01-restricted CD8+ T cell clones responsive to nitroso dapsone-modified peptides Pep1 and Pep3.
• Demonstrated T cell proliferation and effector molecule secretion upon stimulation with modified peptides.
• Observed T cell reactivity against soluble nitroso dapsone forming adducts in situ, but not against unmodified peptides or dapsone.
• Confirmed cross-reactivity between modified peptides with varying cysteine positions.

Conclusions:

• Characterized a drug metabolite hapten CD8+ T cell response restricted by the HLA risk allele HLA-B*13:01.
• Established that the drug-peptide complex, not free drug or peptide alone, is the primary antigen.
• Provided a framework for structural analysis of hapten-HLA binding interactions in drug hypersensitivity.