PHAGOLYSOSOMAL PH IN ALVEOLAR MACROPHAGES FROM SMOKERS AND NONSMOKERS

1 Alveolar macrophages efficiently phagocytize particles deposited in the alveolar part of the lung. Phagolysosomal pH in alveolar macrophag es from rabbits, dogs, baboons and guinea pigs is around 5 pH units. A low pH is of importance for clearance of inorganic particles and prob ably also for defence against bacteria and fungi. 2 Phagolysosomal pH in alveolar macrophages from smokers and non-smokers was measured usin g fluorescein-conjugated amorphous silica particles as a probe, pH was the same in both groups and similar to earlier studies on alveolar ma crophages from animals. 3 The morphological picture between alveolar m acrophages from smokers and non-smokers differed clearly with a high n umber of dense inclusions of great variation in size and shape in macr ophages from smokers. Ingested test particles were located in all type s of inclusions. 4 We conclude that phagolysosomal pH in human alveola r macrophages is similar to that in several animal species and that ii is rather insensitive to influence from the environment.