The CD8+ T-cell receptor (TCR) repertoire in extremely preterm neonates is highly shared and convergent

Neonates have an immunological immaturity which persists from fetal life into the newborn period and can result in a poorly protective response to intracellular pathogens. We have previously shown a less complex TCR repertoire may be responsible for reduced CD8+ T cell immunity in a neonatal murine model of influenza virus infection. Therefore, we sought to determine if there were similar differences in the TCR repertoire across the human life span. High-throughput sequencing of the TCRβ CDR3 regions was performed in sorted, naïve CD8+ T cells from extremely preterm (23–27 weeks gestation), term (39–40 weeks gestation), children aged 16 months to 4 years old, and adults aged 25–50 years (n=5 in each group). There were differences in the CDR3 length across the life span, with preterm infants having a shorter CDR3 length, which was due to fewer N1 and N2 additions (p