Inactivation of staphylococci by alveolar macrophages with preliminary observations on the importance of alveolar lining material.

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Separate groups of rats were challenged with aerosolized Staphylococcus aureus or Staphylococcus albus labeled with phosphorus-32, and intrapulmonary bactericidal activity was determined 6 hours later. The rate of inactivation of S. albus was approximately 10 times greater than that seen with S. aureus. Since the alveolar macrophage defense network is the primary site of inactivation of inhaled bacteria in vitro, phagocytic and bactericidal studies were performed to see whether the in vivo differences described could be reproduced in vitro. These studies demonstrated that, whereas rat alveolar macrophages efficiently phagocytosed both types of staphylococci, only S. albus was killed intracellularly. Intracellular bactericidal activity of alveolar macrophages against S. aureus was further studied by lysing extracellular bacteria with lysostaphin after phagocytosis and performing bacterial counts of aliquots of ruptured cell at 0, 2, 4, and 6 hours. Phagocytosis of S. aureus without bactericidal activity wa...