Abstract
Summary: Phagocytic and bactericidal function of rabbit alveolar macrophages (AMs) lavaged from animals during the course of postnatal maturation was studied. Staphylococcus aureus and a temperature-sensitive mutant of Escherichia coli, which could not replicate at 37° during the functional assays, were employed as test bacteria. Assays of the phagocytic capacity of AMs from rabbits of various age groups revealed no significant differences either in the percentage of AMs which took up bacteria (79–90%) or in the number of bacteria taken up per AM (Table 1). In contrast, bactericidal activity of AMs was found to increase with increasing animal age. No bactericidal activity was detected in AMs from newborn animals (Figs. 1 and 2), whereas AMs from 7-day-old animals exhibited at least a bacteristatic activity against S. aureus (Fig. 1) and AMs from 28-day-old rabbits snowed marked bactericidal activity, essentially the same as that of AMs from adult rabbits. Adult AMs killed 75% of the S. aureus and 60% of the E. coli within 120 min (Figs. 1 and 2).
Speculation: The development of bactericidal activity in AMs during the postnatal period correlates with their previously reported morphologic and biochemical maturation. This developmental pattern of bactericidal activity may indicate that the mechanisms responsible for bacterial killing may not be fully developed at birth but develop during extrauterine life. Alternatively, the large quantities of phagocytized surfactant-like material known to be present in the AMs in the early postnatal period may inhibit their bactericidal activity.
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Zeligs, B., Nerurkar, L. & Bellanti, J. Maturation of the Rabbit Alveolar Macrophage during Animal Development III. Phagocytic and Bactericidal Functions. Pediatr Res 11, 1208–1211 (1977). https://doi.org/10.1203/00006450-197712000-00008
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DOI: https://doi.org/10.1203/00006450-197712000-00008