Alterations in von Willebrand factor antigen in premature infants with respiratory distress syndrome and chronic lung disease.

Elevated levels of von Willebrand Factor Antigen (vWF:Ag) may occur in the presence of endothelial injury, a component in the pathology of acute pulmonary insufficiency. The vWF:Ag levels were examined in 13 well infants (controls) and 20 infants with respiratory distress syndrome (RDS), nine of whom developed bronchopulmonary dysplasia (BPD). All infants were very low birth weight (730 to 1500 g) and premature (25 to 34 weeks estimated gestational age). Plasma samples were obtained at birth and weekly through 28 days of age and frozen at -70 degrees C. The vWF:Ag was quantified by the enzyme linked immunosorbent assay (ELISA) method for 138 plasma specimens; in addition, 77 samples were analyzed for multimer pattern by SDS-agarose (1.7 percent) electrophoresis and densitometric scanning. All groups had elevated mean levels of vWF:Ag, compared to adults. Although levels remained stable over the four week period, the group of infants with BPD had a significantly high mean level of vWF:Ag at 21 days than those groups without BPD (p < 0.05). Visual examination of vWF multimer patterns revealed absence of unusually large vWF multimers and triplet patterns suggestive of increased proteolytic degradation of von Willebrand factor. However, densitometer scanning revealed that samples with higher vWF:Ag levels (> 200 percent) had increased amounts of moderate to smaller sized multimers, regardless of presence or absence of BPD. It is our conclusion that von Willebrand factor antigen levels are nonspecifically elevated in premature infants and that chronic lung disease is associated with even higher plasma values, possibly owing to pulmonary endothelial injury.