Phenotypic markers of alveolar macrophage maturation in pulmonary sarcoidosis

The expression of maturation-associated antigens on alveolar macrophages (AMs) was studied in bronchoalveolar fluid of 30 patients with sarcoidosis and 11 control subjects. The percent of AMs expressing CD14 or CD11b (common for blood monocytes) was significantly increased in patients with active sarcoidosis compared to those with inactive disease, and control subjects. On the other hand, the mean expression of antigens characteristic for mature macrophages showed no significant difference (25F9), or was even increased in patients with sarcoidosis (CD71, KiM8). Since CD14 and CD11b molecules were also frequently expressed on large phagocytes morphologically similar to mature macrophages, and recent studies showed modulation of these glycoproteins by the activation of myeloid cells, our data indicate that the majority of AMs recovered by bronchoalveolar lavage in sarcoidosis are mature, activated cells.