A T-cell functional phenotype common among autoimmune-prone rodent strains

Area of Science:

• Immunology
• Genetics
• Autoimmunity

Background:

• Autoimmunity exhibits genetic links and familial clustering, suggesting shared predispositions.
• Identifying common phenotypic traits in autoimmune-prone individuals is crucial for understanding disease mechanisms.

Purpose of the Study:

• To investigate a shared T-cell phenotype in various autoimmune-prone rodent models.
• To determine if this phenotype is linked to T-cell receptor (TCR) signaling and thymocyte selection.

Main Methods:

• Tested multiple strains of autoimmune-prone mice (MRL, NOD, NZB, NZW, NZB/W F1, SJL, SWR) and rats (DA, BB) for T-cell responsiveness.
• Assessed T-cell activation thresholds via TCR cross-linking in vitro and in vivo.
• Analyzed thymocyte populations, including CD4/CD8 single-positive and heat stable antigen (HSA)hi medullary thymocytes.

Main Results:

• A consistent hyporesponsive T-cell phenotype was identified across all tested autoimmune-prone rodent strains.
• This hyporesponsiveness is T-cell intrinsic, age-independent, and involves an increased TCR activation threshold.
• Inefficient deletion of specific medullary thymocyte populations (CD4+CD8+HSAhi) was observed in hyporesponsive donors.

Conclusions:

• The identified T-cell hyporesponsiveness is a shared trait in autoimmune-prone rodents.
• Increased TCR signaling thresholds may impair negative selection of autoreactive thymocytes, contributing to autoimmunity.