Occupational allergic alveolitis.

Hypersensitivity pneumonitis is an important occupational pulmonary disease. A variety of antigens including foreign proteins and low molecular weight chemicals have been described as etiologic agents. The immunopathogenesis appears to involve activated CD8+ cells as well as activated macrophages. The clinical disease may be acute, subacute or chronic depending upon the nature and level of exposure. Reducing exposure to known antigens is a strategy that appears promising in terms of prevention of irreversible disease.