[Electron microscopical and histochemical investigations of phagocytotic defense reaction of the lung in experimental mineral oil pneumonia (author's transl)].

Phagocytosis of foreign body material (mineral oil) by alveolar macrophages and interstitial localized macrophages is seen in early stages of mineral oil pneumonia studied by electron microscopy and histochemistry. Degradation of phagocytized mineral oil by phagolysosomes is seen in alveolar macrophages, appearing in final stages as empty vacuoles. In contrast, this hydrolytic degradation cannot be found in interstitially localized macrophages. In these cells the mineral oil is present in unchanged form. It seems to be likely that this retention of foreign body material is the reason of granuloma formation. As a non-specific result of mineral oil application there is observed an increased production and extrusion of osmiophilic material (surface active phospholipids) by large alveolar epithel cells.