Aim To examine the function of oxygen-dependent intracellular killing (oxidative burst) in neutrophils of preterm infants and expression of neutrophil adhesion molecules CD11b and CD18.
Methods Blood samples were collected on days 1, 3, and 7 (n = 58), median gestation 29 weeks, median birth weight 1257 g. Neutrophils were stimulated with phorbol myristate acetate (PMA), a strong chemical stimulant and with opsonised Escherichia coli. A non-stimulated sample was included as a control. Neutrophils exhibiting oxidative burst activity produce free radicals, which react with dihydrorhodamine to produce fluorescence. This is detected by a flow cytometer and reported as mean fluorescence index (MnIX). The neutrophil oxidative index is then calculated as the ratio of stimulated : non-stimulated MnIX.
Results All preterm infants expressed CD11b and CD18 antigens, the percentage of neutrophils expressing binding antigens was variable. Neutrophil oxidative burst response to stimulation with PMA and E coli was reduced (see table).
Conclusion This may contribute to susceptibility to infection in this preterm population.