Intrauterine neutrophil activation is associated with pulmonary hemorrhage in preterm infants

¹ Robert Wood Johnson Medical School-UMDNJ, United States

^* To whom correspondence should be addressed. E-mail: mehtara{at}umdnj.edu.

Accepted 9 May 2006

	Abstract

Rationale: 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 hemorrhage in extremely low birth weight infants at an early age after birth.

Objectives: To assess the neutrophil functional activity in cord blood from extremely low birth weight infants who subsequently developed severe pulmonary hemorrhage.

Methods: Neutrophil functional activity was evaluated in the cord blood of preterm neonates (gestational age <28 weeks and weight <800 grams) who developed pulmonary hemorrhage (n=6) and in controls that did not (n=6). Infants with congenital abnormalities, significant maternal complications such as diabetes, pre-eclampsia, hemorrhagic disorders, and connective tissue disease were excluded.

Measurements: Neutrophils isolated from the cord blood immediately following the delivery were tested in order to evaluate neutrophil chemotaxis, random motility, and chemiluminescence. Standard methodology was used to test these parameters.

Main Results: Chemotaxis and chemiluminescence of neutrophils isolated from the cord blood of infants diagnosed with pulmonary hemorrhage was higher than in controls (34.8+/- 2.0 vs. 28.6+/-0.8 µm, P<0.001, and 95.8+/-8.5 vs. 73.2+/-3.6 cpm x 103, P<0.001, respectively). Random motility of the cord blood neutrophils in the extremely low birth weight infants with pulmonary hemorrhage was comparable to those who did not develop this complication (28.6+/-1.2 vs. 25.3+/- 1.2 µm, P<0.09).

Conclusions: Intrauterine induction of the neutrophils' chemotactic activity and metabolic oxygenation may predispose to the development of pulmonary hemorrhage in extremely low birth weight infants with respiratory distress at an early age after birth.

Keywords: neutrophil functional activity, preterm neonates, pulmonary hemorrhage