Abundance of siderophages in sputum - Indicator of an adverse lung reaction to air pollution

OBJECTIVE: To investigate the lung response to traffic-related air pollutio n by enumerating hemosiderin-laden alveolar macrophages (AM) in sputum. STUDY DESIGN: Sputum samples were collected from 103 urban adult males from Calcutta chronically exposed to automobile exhaust. Forty-nine rural indiv iduals served as controls. AM were identified by nonspecific esterase stain ing. Perl's Prussian blue technique was employed for the detection of hemos iderin-laden AM (siderophages). RESULTS: The urban group, consisting of 31 traffic officers, 25 automobile service station workers and 47 street hawkers, had seven times more AM in t heir sputum than did the matched controls, Besides, a remarkable rise (27-f old) in the number of siderophages in sputum was observed in urban individu als. Smoking further elevated the AM count and number of siderophages. CONCLUSION: Abundant siderophages in the urban group may indicate the toxic effect of airborne pollutants on the lung, leading to phagocytosis of dest royed cells, including erythrocytes, and accumulation of iron in AM. Enumer ation of siderophages in sputum appears to be a simple, noninvasive, inexpe nsive cytochemical technique well suited to preliminary assessment of the a dverse effects of air pollution on the lungs in large, population-based stu dies, especially in, developing countries.