Regional defense mechanisms of the guinea pig lung

Many pulmonary diseases, such as tuberculosis, cancer, and pneumonia, are localized to lobes or segments of the lung suggesting regional differences in host defense mechanisms in the lungs. To determine the intrinsic regional differences in transport or phagocytic defense mechanisms, particle deposition, bactericidal activity, and particle transport were measured in each of the 5 individual lobes of guinea pig lungs. Animals were exposed by aerosol to a mixed bacterial suspension containing P. mirabilis labeled with sulfur 35 and S. aureus labeled with phosphorus 32 or P. mirabilis labeled with phosphorus 32 and unlabeled staphylococci. Deposition of particles 3.5 μ or less in diameter was directly proportional to the weight of the lobes; however, on an equal weight basis, no preferential deposition was observed in any of the individual regions. No delay or enhancement in bactericidal activity or transport was observed among the lobes regardless of size or geographic position. These data demonstrated that the pulmonary defense mechanisms of particle transport and bactericidal activity were uniform throughout the lung. It is unlikely that localization in pulmonary diseases is attributable to any inherent geographic differences in intrapulmonary bactericidal or transport activities.