Preterm newborns are more vulnerable to infection than are term newborns and advancing gestational age is associated with increased monocyte immune function. Early growth response-1 gene (EGR-1) is essential in promoting cell differentiation of progenitor cells to macrophages and is induced by lipopolysaccharide (LPS) stimulation and by macrophage-colony stimulating factor (M-CSF). This gene expression has not been studied in newborns. We developed a probe for human EGR-1 using a NcoI fragment of human EGR-1 genomic DNA (ATCC) by subcloning into a pGEM-5Zf vector. The DNA sequence was verified by sequencing analysis. A 32P labeled cRNA probe for Northern analysis was generated by in-vitro transcription. Cord blood was collected from the placenta immediately after delivery and monocytes were isolated by Ficoll gradient separation and adherence. Total cellular RNA was isolated, Northern blot hybridizations performed, and autoradiographs analyzed. Our results show that EGR-1 mRNA is expressed in unstimulated monocytes from three term samples and one preterm sample at 34 weeks gestation. This level of basal expression is likely related to the serum responsive element of the gene. This is the first demonstration of EGR-1 in human neonatal monocytes or macrophages. This methodology provides an opportunity to study whether EGR-1 expression can be upregulated in neonatal monocytes in response to LPS or M-CSF and whether there are differences in this expression related to gestational age of the newborn.

Supported in part by NIH P20RR10256 Kansas IDEA