Insight into normal thymic activity by assessment of peripheral blood samples

Area of Science:

• Immunology
• Developmental Biology
• Cell Biology

Background:

• The thymus is crucial for T cell receptor (TCR) rearrangement and selection, ensuring functional and self-tolerant T cells.
• Understanding how peripheral blood markers reflect thymic function in infants is limited.
• Infant thymic function assessment is vital for diagnosing and managing immune disorders.

Purpose of the Study:

• To compare thymic function markers in the thymus and peripheral blood of infants.
• To establish correlations between peripheral blood and intra-thymic T cell parameters.
• To validate peripheral blood markers for assessing infant thymic activity.

Main Methods:

• Analysis of TCR excision circles (TRECs), TCR delta chain (TCRD) gene rearrangements, and TCR repertoire in thymic and blood samples.
• Quantification of regulatory T cells (Tregs) and FOXP3 mRNA expression using flow cytometry and RQ-PCR.
• Concomitant blood and thymus sample collection from infants undergoing thymectomy.

Main Results:

• Significant correlations were observed between thymic and peripheral blood levels of TRECs, TCRD gene rearrangements, and Tregs.
• Levels of these markers were consistently higher in the thymus compared to peripheral blood.
• TCR repertoire distribution was similar in both sample types, and FOXP3 mRNA levels correlated well.

Conclusions:

• Peripheral blood assessment of TRECs, TCRD rearrangements, and Tregs accurately reflects intra-thymic activity in infants.
• These findings demonstrate a strong correlation between peripheral blood and thymic function parameters during infancy.
• Peripheral blood markers provide a reliable method for estimating thymic capacity and assessing T cell function.