Objective: To study the expression of CD(44) in pneumocytes in pulmonary sarcoidosis.
Methods: CD(44) and AE(1)/AE(3) were detected by immunostaining in lung tissues from 21 cases of pulmonary sarcoidosis, 5 cases of tuberculosis, 4 cases of idiopathic interstitial fibrosis, 3 cases of Wegener's granulomatosis and 8 normal controls. The numbers of CD(44) positive cells and AE(1)/AE(3) positive cells (total alveolar epithelial cells) per three high-power fields were counted, and the ratio of CD(44) cells to AE(1)/AE(3) cells (84 +/- 6) were calculated.
Results: The total number of alveolar epithelial cells (110 +/- 32) and the density of CD(44) cells were significantly higher in sarcoidosis than in the normal lungs. CD(44) (18 +/- 4) staining was localized in the pneumocyte membrane and the positive cells were mostly type II pneumocytes as confirmed by histology.
Conclusion: Proliferation of pneumocytes and increased expression of CD(44) in pneumocyte membrane, especially in the type II pneumocytes, may play an important role in lung inflammation and repair in pulmonary sarcoidosis.