Age-related Changes In T-cell Repertoire Diversity Of Peripheral Lymphocytes In Healthy Children

Objective: A healthy person has a repertoire of more than several million T-cell receptor(TCR)β sequences in circulating T cells.Among the fragments involved in TCR,the CDR3 region is the most diverse part,which is usually used to represent diversity of the whole TCR.Since lymphocyte compartments undergo dramatic changes during childhood,the age-related changes of peripheral lymphocyte subpopulation and TCR diversity are need to be analyzed.We focused on the bio-informatics data mining of the T-cell group library of children and combined with lymphocyte subsets analysis to verify the relationship of frequency of different lymphocyte subsets and TCR diversity of PBMC,exploringpossible influencing factors on the TCR diversity and usage of V-D-J fragments.This study may help to understand the changes of T cell bank of healthy children at different ages,and to provide reference direction for subsequent research.Methods: A total of 81 healthy volunteers(46 males,35 females)aged 0 to 18 years were recruited in this study.We isolate peripheral blood for detailed immunophenotyping.Genomic DNA extacted from PBMC was used for high-throughput sequencing of TCR CD3 sequence.All the data analysis and figure plot were completed by the software ‘R studio’.The default ‘Pearson’ method was used to calculate the coefficient of TCR diversity and age,the coefficient of each lymphocyte subsets and TCR diversity.Results: We have found that the percentage of naive T cells in both CD4+ and CD8+ subsets decrease linearly with age in healthy children.CD4+T cells relative number is positively correlated with TCR diversity but CD8+T cells is negatively.TCR diversity decreased with the increase of age,and the two were moderately correlated.We also observed some significant difference in the frequency of TRBV 10/11/12/13 and TRBJ1/2 usage.Conclusion: 1.This study found that there is a strong correlation between proportion of naive T cells in the lymphocytes and TCR diversity.TCR diversity generally decreases linearly with age in childhood,but it has nothing to do with gender.Through this article,we can further understand the trend of the T cell repertoire of normal children with age.2.The usage frequency of TRBV/TRBJ of different ages has changed fragments and conservative fragments,which can provide help for finding VDJ significantly different genes and provide a reference direction for follow-up research.3.The library diversity of TCRβ chain CDR3 has increased significantly after vaccination,which can provide reference for immune assessment.