Acid phosphatase (EC 3.1.3.2) activity in alveolar macrophages from patients with active sarcoidosis

Five main acid phosphatase (AcP) zones have been recognized and studied by polyacrylamide-gel electrophoresis. Band 5 represents the only tartrate-resistant form and is present in bone osteoclasts and in human alveolar macrophages (AMs). This study was carried out to quantify the presence of total and tartrate-resistant AcP (TrAcP) in AMs from bronchoalveolar lavage (BAL) of 11 patients with first stage sarcoidosis and in 13 nonsmokers and 16 smokers serving as control healthy subjects. The AMs from smokers showed an increase in total AcP activity (115.9 +/- 77.8 mU/10(6)); on the contrary, macrophages of patients with sarcoidosis revealed a consistent decrease in total AcP (27.8 +/- 7.0 mU/10(6)) and particularly the TrAcP subtype (14.8 +/- 3.7 mU/10(6)) in comparison with control nonsmokers (AcP = 42.2 +/- 18.9 mU/10(6) [p = NS]; TrAcP = 35.1 +/- 15.1 mU/10(6) [p less than 0.005]). The decrease in TrAcP activity was inversely correlated with the lymphocyte number (r = -0.75; p less than 0.01), lymphocyte percentage (r = -0.62; p less than 0.05), and CD4/CD8 ratio (r = -0.61; p less than 0.05). After six months of follow-up, the cytologic BAL picture returned completely to normal in five patients with full spontaneous regression of sarcoidosis; and also at the same time, normal values of TrAcP activity were restored. Since TrAcP activity can be easily detected, its possible use, along with the lymphocyte count and CD4/CD8 ratio, as a prognostic indicator of the clinical course of sarcoidosis deserves further investigation.