The clinical role of BAL in pulmonary histiocytosis X.

detection of trace metals in the cell-free BAL fluid, showing high concentrations of tungsten (W), tantalum (Ta) and cobalt (Co) in hard metal lung disease [163]. The quantification of asbestos bodies is best done by filtration of 5-15 ml fresh BAL fluid, cells included, onto millipore filters, and counting the number of asbestos bodies [179]. Uncoated asbestos fibres can only be counted by electron microscopy [177], but this is, so far, without clinical value. Asbestos body counts correlate with the type of asbestos related disorder being higher in those with benign pleural disease or malignant mesothelioma [179]. Asbestos body counts in BAL correlate closely with concentrations of asbestos bodies in lung tissue obtained by biopsy or at autopsy. A BAL count of more than one asbestos body per ml is highly indicative of a lung concentration exceeding 1,000 asbestos bodies per g dry tissue [180, 181]. Only seven percent of non-asbestos exposed white collar workers have asbestos bodies at concentrations > 1·ml·1 BAL fluid [179]. In general, demonstration of dust in the lungs is an indication of exposure but is no evidence of disease. On the other hand, a minority of patients with definite asbestos exposure and disease may have BAL 949