[Hypersensitivity pneumopathies].

Abstract

The diagnosis of hypersensitivity lung diseases in an agricultural, urban or occupational environment is established in two stages: (a) the environmental allergens likely to affect the alveoli and interstitial tissue are identified, and (b) the disease is diagnosed by clinical and radiological examinations but also by methods exploring respiratory function and immune mechanisms. Respiratory function tests show alveolar lesions, and the frequent involvement of the small bronchi is demonstrated by studies of respiratory mechanics. An important component of routine diagnosis is the presence in the serum of precipitating antibodies directed against the causative allergen and above all, bronchoalveolar lavages, which explore the deep lung, reveal distinctive cytological features (infiltration by T-lymphocytes) and lipidic features (fall in lecithins and increase in phosphatidyl-inositol and phosphatidyl-ethanolamine). High microviscosity of the alveolar fluid can be demonstrated by fluorescence polarization methods. A more rational treatment and, most important, measures aimed at preventing the development of a disabling and irreversible pulmonary fibrosis can be based on these findings.