[Granulocyte function in premature infants before the 34th week of pregnancy and in mature newborn infants]

Abstract

Background: Preterm and term neonates have an increased risk to develop severe bacterial infections. Impairment of neutrophil function may be responsible for this increased risk. Other diseases related to prematurity like retinopathia of prematurity (ROP) or broncho-pulmonary dysplasia (BPD) on the other hand may be due to poorly controlled O2-radical production.

Patients and methods: Blood samples of 112 premature (34 weeks of gestation and older) and term neonates were analysed. Blood samples of 23 healthy adults (18 to 50 years old) served as controls. O2-radical production and phagocytosis of neutrophils were determined by flow cytometry, using a commercial test system.

Results: Under the experimental conditions applied, the capacity to produce O2-radicals following vigorous stimulation (E. coli) is comparable between neutrophils of preterm/term neonates and healthy adults. However, unstimulated or weakly stimulated (fMLP) neutrophils of preterm and term neonates show a statistically higher O2-radical production as neutrophils of the control group. The production of oxygen radicals increases during the first 10 days of the life. The capability of neutrophils to phagocytose E. coli is significantly lower in newborns (preterm and term) compared to the adult controls.

Conclusions: The values reported here for phagocytosis and O2-radical production utilizing a commercially available test system may serve as "preliminary normal values" for neonates. No differences were found between the groups of neonates with and without infection. Impaired neutrophil-phagocytosis possibly contributes to the increased risk of preterm and term neonates to acquire bacterial infections. The increased spontaneous O2-radical production, on the other hand, may play a role for the development of so called "free radical diseases" such as ROP or BPD. However, our results cannot add further proof to this hypothesis.