C. Delacourt et al., OXIDANT-ANTIOXIDANT BALANCE IN ALVEOLAR MACROPHAGES FROM NEWBORN RATS, The European respiratory journal, 9(12), 1996, pp. 2517-2524
An oxidant-antioxidant imbalance in neonatal alveolar macrophages (AMs
) may contribute to the increased susceptibility to lung injury descri
bed in the neonatal period. We therefore evaluated oxygen radical prod
uction by rat AMs at various postnatal ages, and measured in parallel
cellular antioxidant enzyme activities. AMs were obtained by bronchoal
veolar lavage from rats aged <24 h, 21 days and 5 weeks, and results w
ere compared to those obtained with adult rat AMs. Intracellular produ
ction of oxygen radical species, estimated fluorometrically using 2',5
'-dichlorofluorescein diacetate as the substrate, was significantly re
duced in neonates as compared with adults, both in the presence and in
the absence of cell stimulation with phorbol myristate acetate (PMA)
or opsonized zymosan, A similar pattern was observed for the extracell
ular release of oxygen radical species, evaluated by lucigenin-enhance
d chemiluminescence (CL) or peroxidase-catalysed CL oxidation of lumin
ol: peak CL values measured after cell stimulation with PMA or opsoniz
ed zymosan remained significantly lower for AMs from newborn rats than
for AMs from adults, By contrast, high values for antioxidant enzyme
activities (superoxide dismutase and glutathione peroxidase) in AMs we
re demonstrated in newborns as compared to adults. We conclude that hi
gh antioxidant activity in rat AMs after birth may be at least partly
responsible for the low production of oxygen metabolites observed duri
ng the same period.