Pulmonary host defence mechanism in newborn non-humanprimate lungs

ABSTRACT

Using the technique of Broncho-alveolar lavage (BAL), alveolar macrophages (AM) from the lower respiratory tract of five newborn rhesus monkeys (1 to 2 days of age) with five adult controls were isolated. Chemotactically responsiveness phagocytic assays and killing capacity of the above macrophages were tested. It was found that the alveolar macrophages from the adult primate lung were chemotactically responsive while the alveolar macrophages from the newborn lung were chemotactically impaired. In phagocytic assays, the percentages of alveolar macrophages from the lung which had pahgocytised 3 or more candida albican blastospores ranged from 56 to 89 while macrophages from newborn scored as 0 to 10. The killing capacity of alveolar macrophages from adult lung ranged from 70 to 92 per cent while macrophages from newborn scored at 1 to 12 per cent. Moreover, a substantial increase in neutrophil count was obtained in the second series of lavages and a significant migration of neutrophils into the adult lungs was confirmed. These results clearly indicate that the newborn non-human primate lungs are functionally deficient in defence mechanism compared to adults.