Ultrastructural changes in bronchoalveolar lavage cells in sarcoidosis and comparison with the tissue granuloma

The authors undertook this study to determine whether there were any morphologic changes in bronchoalveolar lavage lymphocytes and macrophages in sarcoidosis and, in particular, to determine whether changes described previously in the mononuclear phagocytes of sarcoid granulomas were also evident in such cells obtained by lavage. Lavage cells from 28 sarcoidosis patients were studied by transmission electron microscopy and compared with lavage cells from 17 control subjects and with lung tissue granulomas from 5 sarcoidosis patients. Interactions between mononuclear phagocytes, especially subplasmalemmal linear densities, and between these cells and lymphocytes were observed in both the tissue granulomas and lavage specimens from sarcoidosis patients. Subplasmalemmal linear densities were never observed in control lavage specimens. Fully developed epitheloid cells were not identified in lavage specimens, but differences were nevertheless found between the lavage cells from sarcoidosis patients and control subjects: in particular, alveolar macrophages in sarcoidosis were larger and showed better developed pseudopodia, more marked polarity, less nuclear heterochromatin, and lysosomes that were larger and more numerous but less electron-dense than normal. Lymphocytes were also enlarged and contained more lysosomes. It is concluded that although there are only a few similarities between the cells of the granuloma and those obtained by bronchoalveolar lavage in sarcoidosis, there are noticeable differences between the lavage cells of sarcoidosis patients and control subjects. In sarcoidosis, a variable proportion (10-70%) of the lavage cells show morphologic features of "activation."