Background: Sarcoidosis and chronic beryllium disease (CBD) are inflammatory conditions in which oxidative stress state may be crucial for disease outcome. This study compares haem oxygenase-1 (HO-1) extracellular activity for the first time in patients with sarcoidosis or CBD and in healthy controls.
Materials and methods: Induced sputum was recovered using a standard protocol. Pulmonary function tests (PFT) were performed by conventional methods. T lymphocyte subsets (CD4 and CD8) were measured by flow activated cell shorter (FACS). The HO-1 and nitrite levels were measured by a bilirubin-biliverdin reductase-dependent reaction and Greiss reaction respectively. Ferritin and iron levels were measured by enzymatic reaction and chemiluminometric immunoassay respectively.
Results: The mean percentage of lymphocytes was significantly higher in the 36 sarcoid patients compared with that in the 17 controls (P=0.001). The mean CD4/CD8 ratio was significantly higher in the sarcoid and the 10 CBD patients compared to that in controls (P=0.000 and 0.002 respectively), as was the mean HO-1 activity (P=0.045 and 0.041 respectively). The HO-1 activity did not differ with the sarcoidosis stage. The HO-1 level and PFT parameters were negatively correlated. The differences in mean nitrite, ferritin and iron levels were non-significant between the three groups. The HO-1 and ferritin levels were correlated (P=0.008).
Conclusions: We succeeded in non-invasively measuring the activity of HO-1 from cells of airways in spite of its being an intracellular enzyme. The HO-1 levels in sarcoidosis and CBD were abnormally elevated.