Relevance of asbestos bodies in sputum.
The presence of asbestos bodies (ABs) in sputum specimens of individuals with occupational asbestos exposure has been well-documented. The aim of this study was to determine their clinical relevance in comparison to the concentration of AB in bronchoalveolar lavage (BAL) and lung tissue. Subjects were included following a well-documented exposure of asbestos history (n = 93) or BAL fluid analysis positive for ABs (n = 42). The subjects with a well documented history of AB exposure were divided into three groups: heavy (Group 1, n = 29); moderate (Group 2, n = 31); or occasional exposure (Group 3, n = 33). BAL fluid was available from all subjects, and lung tissue from 21 subjects. To assess the variability, 10 sputum positive subjects collected subsequent sputum on days 2, 7, 14, 30 and 90. ABs were determined by light microscopy after membrane filtration of specimen digests. The mean sputum AB content was highest in Group 1 (2.4 +/- 5.5 AB.mL-1), lower in Group 2 (0.2 +/- 0.3 AB.mL-1) and lowest in Group 3 (0.1 +/- 0.1 AB.mL-1) suggesting a correlation with cumulative exposure. However, many negative sputum samples were noted, when BAL specimens were positive. The AB content of sputum and BAL specimens did not correlate. ABs were found in sputum of all subjects with a tissue content of > 1,000 AB-cm-3, but in none with contents of