CD8⁺ T cell self-tolerance permits responsiveness but limits tissue damage.

Area of Science:

• Immunology
• T cell biology
• Autoimmunity

Background:

• Self-specific CD8+ T cells can evade deletion, but their behavior in vivo remains poorly understood.
• Understanding these cells is crucial for managing autoimmune diseases.

Purpose of the Study:

• To characterize the properties and capabilities of self-specific CD8+ T cells in a physiological context.
• To investigate the mechanisms underlying functional self-tolerance in CD8+ T cells.

Main Methods:

• Characterization of polyclonal CD8+ T cells specific for tyrosinase-related protein 2 (Trp2) in wild-type and Dct-deficient mice.
• Analysis of phenotypic and gene expression profiles, cell expansion, differentiation, and immunopathology mediation.

Main Results:

• Pre-immune Trp2/K(b)-specific CD8+ T cells showed similar phenotypes and frequencies in wild-type and Dct-deficient mice.
• Despite comparable initial responses, wild-type cells exhibited blunted expansion and less CD25+ differentiation.
• Adoptively transferred wild-type cells mediated vitiligo less efficiently, indicating functional self-tolerance.

Conclusions:

• CD8+ T cell self-specificity is not reliably predicted by precursor frequency, phenotype, or initial responsiveness.
• Deficient activation-induced CD25 expression and specific gene expression patterns may identify functionally tolerant self-reactive CD8+ T cells.