ESPE Abstracts

Background: Glucocorticoids play an important role in the developing fetus, the most important of which is lung maturation by increasing surfactant production and release. Glucocorticoid receptor (GR) functioning changes throughout the fetal period, especially during the transition to extrauterine life. Given the importance of glucocorticoids in lung development and functioning, studying glucocorticoid sensitivity in this population would be helpful, especially in the preterm population, to determine steroid treatment for better lung outcomes. Few groups have characterised the GR and its sensitivity using cord blood monocytes.

Objective and hypotheses: We propose to use cord blood monocytes to characterise the GR and its sensitivity in term neonates using a fluorescein labeled dexamethasone (F-Dex) monocyte binding assay.

Method: Twenty cord blood samples were collected from term neonates (37–40 weeks gestation) born to mothers with no pregnancy complications and no labor (scheduled C-section). We compared the F-Dex binding in this group to 50 healthy pediatric pts (5–22 years old).

Results: We found that the F-Dex binding of the studied neonatal population was similar (within 1 S.D.) to the pediatric population through the initial concentration ranges of F-Dex. However, there was an increase in binding in the neonatal population in comparison to the pediatric population at the highest concentration.

Conclusion: A cord blood F-Dex monocyte binding assay can be used to characterise the GR in neonates. It showed that there is a difference in F-Dex binding at the highest concentrations in the neonate population, as compared to our pediatric population, most likely related to changes in the GR in the process of adaptation to extrauterine life. Our future studies will use this assay to study the GR in preterm neonates to help us determine appropriate steroid dosing and better lung outcomes in these patients.