A TCR affinity threshold regulates memory CD4 T cell differentiation following vaccination

Area of Science:

• Immunology
• Vaccinology

Background:

• Diverse antigen-specific memory T cell repertoires are crucial for pathogen defense.
• Subunit vaccines combining antigens with TLR agonists effectively induce T cell responses.

Purpose of the Study:

• To evaluate the stability and diversity of memory CD4 T cell repertoires after peptide or protein vaccination.
• To understand the mechanisms regulating T cell repertoire evolution during memory formation.

Main Methods:

• Examined the evolution of antigen-specific CD4 T cell receptor (TCR) repertoires post-vaccination.
• Compared repertoire dynamics following peptide versus protein antigen administration.
• Investigated the role of CD27-mediated signaling in T cell memory maintenance.

Main Results:

• Both peptide and protein vaccines induced diverse effector CD4 TCR repertoires.
• Peptide vaccines skewed memory repertoires toward high-affinity clonotypes.
• Protein vaccines maintained low-affinity clonotypes, dependent on CD27 signaling.

Conclusions:

• A novel affinity threshold influences memory CD4 T cell differentiation post-vaccination.
• Non-apoptotic cell death may regulate CD4 T cell clonal selection.
• Vaccine formulation critically impacts the resulting memory T cell repertoire composition.