Abstract
ABSTRACT: Bronchoalveolar macrophages (BAM) protect the adult lung from low level microbial contamination. The antimicrobial activity of human newborn RAM is unknown. BAM were isolated from effluents of suctioned, intubated newborns and from bronchoalveolar lavage of healthy, nonsmoking adult volunteers. An in vitro cytologic slide assay was developed and used to ascertain: 1) inhibition of intracellular filamentation of Candida albicans (active yeast growth) and 2) killing + digestion of ingested C. albicans. The ability to restrict intracellular yeast filamentation was markedly different for human newborn versus adult BAM. Adult BAM were five times more effective in restricting intracellular filamentation of Candida compared to newborn cells (p < 0.01). Nonfilamented ingested yeast were also handled differently by newborn and adult macrophages. Nonfilamented yeast were killed and digested by adult BAM at a rate that was 2.5 times above that noted in neonatal lung macrophages (p < 0.005). However, no differences were found in the total number of killed + digested Candida within human newborn and adult BAM [adult = 32A ± 10.5% (n = 5), newborn <1200 g = 39.6 ± 16.8% (n = 8), and newborn >1200 g = 30.2 ± 11.1 % (n = 16), mean ± S.D.]. Neonatal BAM were able to destroy C. albicans at a level equivalent to adult cells because there newborn phagocytes allowed intracellular Candida to enter a state of active growth, thereby rendering the yeast more susceptible to killing and digestion. The anti-Candida activity noted in lung macrophages recovered from normal 1-day-old and adult rabbits was similar to that seen in human BAM. Kinetic studies of intra- and extracellular yeast filamentation with time revealed that extracellular yeast were unrestricted in their ability to grow (filamentation = 98 ± 0.5% by 2 h). Bonchoalveolar macrophages recovered from rabbits exposed to 95 + % O2 for 96 h after birth had a 2-fold higher rate of intracellular Candida filamentation when compared to BAM lavaged from newborn rabbits raised in room air [66.3 ± 5.9% versus 33 ± 13.5% (mean ± SD, p < 0.025)]. Oxygen exposure did not alter macrophage phagocytosis. We conclude that oxygen therapy may be an important factor underlying the fungistatic limitations of BAM from newborns undergoing intensive care.
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D'Ambola, J., Sherman, M., Tashkin, D. et al. Human and Rabbit Newborn Lung Macrophages Have Reduced Anti-Candida Activity. Pediatr Res 24, 285–290 (1988). https://doi.org/10.1203/00006450-198809000-00001
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DOI: https://doi.org/10.1203/00006450-198809000-00001