Characterization of Regulatory T Cells in Preterm and Term Infants

Our study aimed to study regulatory T cells (Tregs) and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. In an observational study, we used a three-color flow cytometry for determination of Tregs and their expression of CD45RA, HLA-DR, and CD39 in preterm and full-term infants. The percentages of CD4 + CD25 +high Foxp3 + , CD39 + Tregs, HLA-DR + Tregs and the expression of Foxp3 + in CD4 + CD25 +high Foxp3 Tregs cells were significantly lower in neonates when compared to healthy adult controls. The levels of naïve resting Tregs (CD45RA + Tregs) were significantly higher in neonates than controls. The percentages of CD4 + CD25 +high Foxp3 + Tregs, total CD4 + CD25 + and CD4 + CD25 +high were significantly higher in preterm infants when compared to the full-term group. Moreover, CD45RA + Tregs were significantly higher in preterm than in term infants. We found significant inverse correlations between the gestational age and the levels of both Tregs (r = − 0.395, p = 0.017) and CD45RA + Tregs (r = − 0.422, p = 0.010). Relative to full-term, the frequencies, and phenotypes of Tregs were affected by prematurity. A larger longitudinal study with a sufficient number of newborns is needed to investigate the Treg pool of term and preterm infants thoroughly and to explore the association between the Treg pool and clinical variables.