Evaluation of alveolitis by studies of lung biopsies.

Immunocytochemical studies of lung biopsies from patients with cryptogenic fibrosing alveolitis and those having fibrosing alveolitis associated with scleroderma show that numerous T-cells occur in the alveolar walls and septa of all patients with these diseases, implying that cell-mediated hypersensitivity reactions are involved in the pathogenesis. However, B-lymphocytes, mainly within lymphoid follicles, are also present and, in the CFA group, such patients, and those with less than 50% T-suppressor/cytotoxic cells in the diffuse T-cell infiltrates, may have a poorer prognosis. Interleukin-2 receptor expression indicates that T-cell activation is occurring within the lungs, and there is evidence that interstitial monocytes/macrophages and alveolar epithelial cells may play a more important role in antigen presentation than alveolar macrophages. These observations on the features of the inflammatory response in the interstitial tissues of patients with fibrosing alveolitis need to be incorporated into the existing hypothesis on pathogenetic mechanisms based mainly on lavage findings of alveolar macrophages and granulocytes.