P-selectin expression by endothelial cells is decreased in neonatal rats and human premature infants

Decreased adhesion of neutrophils to endothelial cells and delayed transend othelial cell migration of neutrophils have been consistently reported in n eonatal animals and humans and contribute to their susceptibility to infect ion. The delayed transmigration of neutrophils is especially prevalent in p remature neonates. To define the nature of this defect, we used an in vivo animal model of inflammation and found that radiolabeled leukocytes from ad ult rats transmigrated into the peritoneum of other adult rats 5 times more efficiently than they did in neonatal rats (P = .05), This indicated that defects in neonatal neutrophils could not completely account for the delaye d transmigration, Delayed transmigration in the neonatal rats correlated wi th a defect in the expression of P-selectin on the surface of their endothe lial cells, We found a similar P selectin deficiency in endothelial cells l ining mesenteric venules and umbilical veins of human premature infants whe n compared with term human infants. The decreased P-selectin in premature i nfants was associated with decreased numbers of P selectin storage granules and decreased P-selectin transcription. Decreased P-selectin expression on the surface of endothelial cells in preterm infants may contribute to dela yed neutrophil transmigration and increased susceptibility to infection. (C ) 1999 by The American Society of Hematology.