ANALYSIS OF AIRSPACE AND INTERSTITIAL MONONUCLEAR CELL-POPULATIONS IN HUMAN DIFFUSE INTERSTITIAL LUNG-DISEASE

Abstract

Increased numbers of mononuclear cells are found in the pulmonary interstitium and airspaces in chronic fibrotic lung diseases. Light and electron microscopic study of lung biopsy specimens from 28 cases of diffuse interstitial lung disease and of 7 normal lung tissue specimens permitted semiquantitative analysis of the numbers and types of mononuclear cells found in the airspaces and interstitium. Pulmonary alveolar macrophages and lymphocytes were the predominant cell types free in the airspaces in normal lung tissue and in specimens from patients with chronic fibrotic lung diseases. Increased percentages of lymphocytes were found in the airspaces of patients with diffuse interstitial lung diseases. An approximately 10-fold or greater increase in the percentage of airspace lymphocytes was found in the lungs of patients with hypersensitivity pneumonitis, connective tissue diseases and lymphoid interstitial pneumonitis, whereas an approximately 4-fold or smaller increase was found in idiopathic pulmonary fibrosis, sarcoidosis and several other fibrotic diseases. Intense interstitial mononuclear cell infiltration was seen in many specimens, but could not be directly correlated with the percentage of airspace lymphocytes in individual cases. Each tissue demonstrated what appeared to be stages in a series of events by which lymphocytes and macrophages migrate between the interstitium and the airspaces. Characterization of the interstitial and alveolar mononuclear cell populations may provide better understanding of the pathophysiology of chronic fibrotic lung disease.