Intrauterine neutrophil activation is associated with pulmonary haemorrhage in preterm infants.

Background: Clinical and experimental studies showing lung damage associated with biologically active neutrophil derivatives suggests the possibility that intrauterine neutrophil activation may predispose to the development of pulmonary haemorrhage in extremely low birthweight infants early after birth.

Objectives: To assess neutrophil functional activity in cord blood from extremely low birthweight infants who subsequently developed severe pulmonary haemorrhage.

Methods: Neutrophil functional activity was evaluated in the cord blood of preterm neonates (gestational age <28 weeks and weight <800 g) who developed pulmonary haemorrhage (n = 6) and in controls who did not (n = 6). Infants with congenital abnormalities and noteworthy maternal complications such as diabetes, pre-eclampsia, haemorrhagic disorders, and connective tissue disease were excluded. Neutrophils isolated from cord blood immediately after delivery were tested to evaluate neutrophil chemotaxis, random motility, and chemiluminescence. Standard methodology was used.

Results: Chemotaxis and chemiluminescence of neutrophils from cord blood of infants with pulmonary haemorrhage was higher than in the controls (34.8 (2.0) v 28.6 (0.8) microm, p<0.001, and 95.8 (8.5) v 73.2 (3.6) cpm x10(3), p<0.001 respectively). Random motility of cord blood neutrophils was comparable in the two groups (28.6 (1.2) v 25.3 (1.2) microm, p<0.09).

Conclusions: Intrauterine induction of chemotactic activity and metabolic oxygenation of neutrophils may predispose to the development of pulmonary haemorrhage in extremely low birthweight infants with respiratory distress early after birth.