Table 2.

Characteristic features of allergic alveolitis

Clinical signs	Bilateral lung crackles
Chest radiograph	Pulmonary infiltrates [5]
CT scan	HRCT can identify features such as ground glass shadowing and air trapping even when the X-ray is normal [6,10]
Gallium scan	Uptake reflects alveolar macrophage activation [7]
TcDTPA lung clearance	Indicates increased alveolar permeability and subclinical inflammation [8,9]
Lung function	Restriction of lung volumes [11], impaired gas diffusion, hypoxaemia and airways obstruction [12]
Systemic signs	Temperature and neutrophil leucocytosisin acute exacerbation
Bronchial lavage	Initial neutrophil alveolitis followed by lymphocytic alveolitis
Lung biopsy	Lymphocyte infiltrate, granuloma formation, fibrosis