Characterization of the inflammatory and immune effector cells in the lung parenchyma of patients with interstitial lung disease
The pathogenesis of the interstitial lung disorders is intimately related to the number, type, and state of activation of inflammatory and immune effector cells (the alveolitis) within the alveolar structures. To directly characterize the type and status of the cells comprising the alveolitis of various interstitial lung disorders, a method was developed to isolate inflammatory and immune effector cells from open lung biopsies of patients with idiopathic pulmonary fibrosis (n = 9) and sarcoidosis (n = 6). The cells isolated from these biopsies were compared with effector cells obtained from normal lung (n = 3). The effector cell populations in normal lung contained alveolar macrophages (84 ± 17%), lymphocytes (16 ± 4%), and rare polymorphonuclear leukocytes (<1%); of the lymphocytes present, 73 ± 4% were T-lymphocytes, 7 ± 2% were 'activated' T-lymphocytes, and 9 ± 2% were B-lymphocytes. In contrast, a characteristic feature of the alveolitis of idiopathic pulmonary fibrosis was the presence of increased proportions of polymorphonuclear leukocytes, primarily neutrophils (18 ± 4%); the percentages of lymphocytes and various lymphocyte subpopulations were similar to those found in the normal lung. By comparison, the alveolitis of sarcoidosis was characterized by the presence of increased proportions of lymphocytes (57 ± 7%). T-lymphocytes (91 ± 5%), and 'activated' T-lymphocytes (19 ± 4%); neutrophils were rarely found in the lung of nonsmoking patients with sarcoidosis. The proportions of various inflammatory and immune effector cells isolated from the lung of normal subjects as well as from biopsies of patients with idiopathic pulmonary fibrosis and sarcoidosis were similar to those cell populations that were present in the respective bronchoalveolar lavage fluids. Thus, the alveolitis of the interstitial lung diseases can be directly characterized by the types of inflammatory and immune effector cells present within the lung parenchyma. In addition, the cells recovered by bronchoalveolar lavage accurately reflect the alveolitis of these disorders.