L-selectin is down-regulated in umbilical cord blood granulocytes and monocytes of newborn infants with acute bacterial infection.

The leukocyte glycoprotein L-selectin mediates an early step in the recruitment of leukocytes to sites of inflammation. L-Selectin surface expression is rapidly down-regulated by inflammatory signals in vitro. In a prospective study, we found L-selectin expression on umbilical cord blood granulocytes and monocytes to be significantly decreased in newborn infants with acute bacterial infection compared with controls (p < 0.01). A significantly reduced L-selectin expression of both granulocytes and monocytes was also found to be associated with an increased neutrophil immature/total ratio (p < 0.01) but not with other laboratory markers of neonatal sepsis. There was no apparent impact of prematurity, low birth weight, gestational hypertension, or gestational diabetes on L-selectin expression. Although the mode of delivery did not affect granulocyte L-selectin expression, umbilical cord blood monocytes showed an increased L-selectin expression after emergency cesarean delivery compared with samples obtained after elective cesarean or vaginal delivery (p < 0.01). We conclude that acute systemic inflammation results in down-regulation of granulocyte and monocyte L-selectin expression in vivo similar to that observed in vitro.