• cryptogenic fibrosing alveolitis;
  • tumour necrosis factor-α;
  • pulmonary fibrosis;
  • type II pneumocyte;
  • macrophage;
  • bronchial epithelium

We have studied 15 cases of cryptogenic fibrosing alveolitis stained with a monoclonal antibody reactive with human tumour necrosis factor-α (TNFα), a cytokine that has been implicated in inflammation and fibrosis. Seven were examples of lone cryptogenic fibrosing alveolitis and eight were examples of cryptogenic fibrosing alveolitis in patients with systemic sclerosis. There was widespread staining of epithelial cells, particularly hyperplastic type II pneumocytes. Macrophages stained only weakly. In a control group of 10 patients dying of unrelated conditions, staining for TNFα was weak and, in the alveolar epithelium, was confined to a very occasional type II pneumocyte. The strong expression of TNFα in hyperplastic type II pneumocytes suggests that TNFα produced during alveolar epithelial regeneration may play a part in the fibrosis seen in this disease.