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 CD4CD25Foxp3, CD39 Tregs, HLA-DR Tregs and the expression of Foxp3 in CD4CD25Foxp3 Tregs cells were significantly lower in neonates when compared to healthy adult controls. The levels of naïve resting Tregs (CD45RATregs) were significantly higher in neonates than controls. The percentages of CD4CD25Foxp3Tregs, total CD4CD25 and CD4CD25 were significantly higher in preterm infants when compared to the full-term group. Moreover, CD45RATregs 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 CD45RATregs (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.