Interleukin-8 expression by fetal and neonatal pulmonary cells in hyaline membrane disease and amniotic infection.

IL-8, a chemokine with striking neutrophil-activating properties, is important in the pathogenesis of various disorders of the adult lung. Little is known about its production and possible role in fetal and neonatal lung disorders. We therefore examined IL-8 expression by immunohistochemistry in lung tissue from neonates with hyaline membrane disease, from fetuses with amniotic infection, and from a fetal control group with noninflammatory diseases. In the majority of cases with hyaline membrane disease, intense IL-8 immunoreaction was seen in fetal and neonatal neutrophils and in almost half of these cases, in epithelial cells of the terminal airways as well as in the connective tissue cell compartment. In contrast, in the amniotic infection group, strong IL-8 immunostaining was almost exclusively seen in maternal aspirated neutrophils. Little or no IL-8 signal was seen in the control cases in all cell types examined. Also, no IL-8 production by fetal lung cells was detected in fetuses <18 wk of gestation. The marked presence of IL-8 in all cell types of the lung in hyaline membrane disease cases indicates a role for IL-8 in the pathobiology of hyaline membrane disease possibly similar to that in adult respiratory distress syndrome. It further suggests that the cytokine network of the fetal lung is already well developed by the second trimester of pregnancy.