Thymic selection of the T cell receptor repertoire is biased toward autoimmunity in females.

Female thymocytes show a 2.4-fold higher prevalence of TCRs specific to autoimmunity-related self-antigens than males, indicating a sex-biased bias in thymic selection.

• Why it matters: Autoimmune diseases predominantly affect women, but the underlying mechanisms remain unclear. Understanding sex differences in T cell development could reveal why women are more susceptible.
• What they did: The study analyzed TCR repertoires from male and female thymocytes and T cells, focusing on gene usage, diversity, and self-antigen specificity, with a particular emphasis on autoimmune-related TCRs.
• The result: Findings demonstrate a sex-specific imbalance in thymic selection favoring autoimmunity-associated TCRs in females, offering insights into the biological basis for increased autoimmune disease risk in women.