DO11.10 and OT-II T cells recognize a C-terminal ovalbumin 323-339 epitope

Area of Science:

• Immunology
• T cell immunology
• Antigen presentation

Background:

• The ovalbumin (OVA)323-339 peptide is a well-characterized model antigen for studying T cell recognition.
• Understanding the precise T cell receptor (TCR) contact residues and epitope boundaries is crucial for dissecting immune responses.

Purpose of the Study:

• To delineate the fine specificity of T cell recognition for the OVA323-339 peptide.
• To identify critical amino acid residues involved in TCR-peptide interactions.
• To investigate the potential for multiple peptide-MHC binding registers.

Main Methods:

• Amino- and carboxy-terminal truncations of the OVA323-339 peptide were used to define epitope ends.
• Single amino acid substitutions within the peptide were employed to identify key TCR contact residues.
• Analysis of T cell clones with specificity for OVA323-339.

Main Results:

• Both DO11.10 and OT-II T cells recognize a C-terminal epitope (residues 329-337) of OVA323-339.
• Amino acid 333 is a primary TCR contact residue for both T cell types, with residue 331 serving as a secondary contact.
• Differences in secondary contact residue importance and flanking residue influence were observed between DO11.10 and OT-II cells.
• Additional T cell clones recognized epitopes in the N-terminal or central regions of the peptide.
• Evidence suggests OVA323-339 can bind to I-Ad in at least three different registers.

Conclusions:

• The OVA323-339 peptide contains a nested set of T cell epitopes.
• Multiple MHC binding registers contribute to the presentation of OVA323-339.
• These findings highlight the intricate nature of peptide-MHC-TCR interactions and antigen recognition.