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The ontogeny of pulmonary defenses: alveolar macrophage function in neonatal and juvenile rhesus monkeys
G Kurland1, A T Cheung, M E Miller
1Department of Pediatrics, University of California Davis, School of Medicine 95616.
Abstract:
Using the technique of bronchoalveolar lavage, we isolated alveolar macrophages (AM) from the lower respiratory tract of newborn (1-4 days of age), infant (6-10 days of age), juvenile (3-6 months of age), and adult rhesus monkeys. The AM thus obtained were assayed in vitro to determine their chemotactic, phagocytic, and candidicidal capabilities. The predominant (greater than or equal to 89%) cell type in bronchoalveolar lavage effluent in all ages was the AM. Chemotaxis, phagocytosis, and killing of Candida albicans were markedly impaired in neonatal AM as compared with those from infants, juveniles, and adults. AM chemotactic activity achieved normal adult values by 6 days of age. Phagocytosis, and to a lesser extent candidicidal activity, were significantly improved in 6-day-old animals, but adult levels were still not achieved even by 6 months of age.
Insights
Neonatal rhesus monkey alveolar macrophages (AM) show impaired immune functions like chemotaxis and phagocytosis. These functions improve with age, but adult levels are not reached by six months.
Area of Science:
- Immunology
- Developmental Biology
- Primate Research
Background:
- Alveolar macrophages (AM) are crucial immune cells in the lower respiratory tract.
- Understanding the maturation of AM function is vital for assessing infant respiratory health.
Purpose of the Study:
- To investigate the functional capabilities of alveolar macrophages (AM) in rhesus monkeys at different developmental stages.
- To determine the age at which AM function matures in rhesus monkeys.
Main Methods:
- Bronchoalveolar lavage was used to isolate AM from newborn, infant, juvenile, and adult rhesus monkeys.
- In vitro assays were performed to assess AM chemotaxis, phagocytosis, and candidicidal activity against Candida albicans.
Main Results:
- Neonatal AM exhibited significantly impaired chemotaxis, phagocytosis, and candidicidal capabilities compared to older age groups.
- Chemotactic activity reached adult levels by 6 days of age.
- Phagocytic and candidicidal activities improved by 6 days but did not reach adult levels even by 6 months of age.
Conclusions:
- Immune function of alveolar macrophages (AM) in rhesus monkeys is immature at birth.
- Significant functional improvements occur within the first week of life, with further maturation continuing for at least six months.
- These findings highlight the prolonged developmental trajectory of innate immune cells in the respiratory tract.