Nonspecific esterase activity of human alveolar macrophages in routine cytology

Alpha-naphthyl acetate esterase (ANAE) activity in alveolar macrophages was demonstrated in air-dried smears from samples of 82 sputa, 47 bronchial secretions and 14 bronchial lavages from 113 patients. Enzyme activity was estimated by a semiquantitative scoring method. There was a 7.4% loss of activity after 24 hours of storing the unfixed material, increasing to 14.4% after three days, while storing the air-dried smears for up to four weeks did not change the ANAE activity. The mean cellular esterase activity was correlated to the clinical and cytologic findings. A stringent correlation could be found for patients smoking more than 30 cigarettes a day; they had a 17% increase in activity as compared to nonsmokers. In patients with bronchial asthma, the activity was 18% higher than the total mean. In three patients with pulmonary embolisms, the ANAE activity was also increased. Treatment with a combination of cytostatics and a corticoid caused a severe decrease. No correlation could be found to age, sex, inflammation or malignant or cardiac diseases. These findings indicate that the application of the ANAE reaction to routine cytologic specimens can contribute to the functional characterization of human alveolar macrophages.