Elevated histamine content of lung lavage in human asbestosis

Abstract

Increased histamine levels in lung lavage have been previously reported in humans with idiopathic fibrosing alveolitis and mast cell proliferation was documented on lung tissue. Similarly, mast cell proliferation has been documented in experimental asbestosis. To evaluate the relevance of these observations to human asbestosis, we performed bronchoalveolar lavage in 10 normal volunteers (group N) and 22 long-term asbestos workers from the mines and mills of Quebec. The 22 asbestos workers were evaluated by standard clinical, functional, radiographic, and gallium-67 lung uptake tests. Five did not have any abnormality suggestive of asbestosis and constituted group A. The 6 in group B were without sufficient criteria for well-established asbestosis, but their lung pressure-volume curve was rigid and⁶⁷Ga lung uptake was increased; the 11 in group C had well-established asbestosis. In addition to standard parameters of BAL cellularity and biochemistry, we measured histamine levels by fluorometric method. In normals, histamine levels were 1.0 ± 0.3 ng/ml, in group A 1.25 ± 0.37 ng/ml (NS), in group B 2.26 ± 0.86 ng/ml (P < 0.05 B vs A or N), and in group C it was 2.65 ± 0.44 ng/ml (P < 0.05 C vs A or N). BAL eosinophils were absent in normals and group A, 272 ± 136/ml in group B, and 764 ± 350 in group C (P < 0.05 for groups B and C vs normals and group A), but did not correlate with histamine content of BAL. This study provides evidence of an elevated content of histamine in the bronchoalveolar milieu of patients with early and late asbestosis. This finding is of interest in relation to the potential role of the mast cell in the disease process.