[The importance of assessing angiotensin-converting activity in silicosis patients]

The macrophage cells have an essential role in the pathogenesis of silicosis. After the endocytosis of silica grains, the lung macrophage demonstrates an active state, associated with high levels of lysosomal enzymes, expressed also in serum. A similar active state of macrophages is evident in sarcoid lung which manifests also an intensive serum activity of angiotensin-converting enzyme. The angiotensin-converting assay in the serum of 116 silicotic patients revealed over 60 per cent higher levels than in normals. Such increased levels were present more frequently among the patients with early studies of silicosis. In the same patients, the serum acid phosphatase activity, a marker of macrophage activity, and also serum lactate dehydrogenase activity, were higher than in normal individuals. On present evidence, it can be appreciated that increased serum levels of angiotensin-converting activity could be the expression of an active progressive state of silicosis.