Pigeon-serum-induced hypersensitivity pneumonitis in the dog.

Pigeon serum (PS) is one of the most common causes of hypersensitivity pneumonitis (HP). PS-induced HP was examined in a dog model. The dogs (n = 6) were immunized by i.m. injections of PS, followed by insufflation with aerosolized PS, while all control dogs (n = 3) received saline only. All animals insufflated with PS developed tachypnea 2-4 h after PS inhalation. After PS insufflation, a significant decrease in arterial oxygen tension (PaO2) was detected in sensitized dogs. No change in PaO2 was detected in sensitized dogs after saline or in the controls after PS insufflation. In intradermal skin tests with PS antigen, a positive skin reaction was found in 3/6 dogs in 30 min, and in 5/6 dogs in 6 and 48 h after the PS injections. Sensitized dogs showed a significant increase in PS-specific IgG in serum and lavage fluid (LF). In LF of sensitized dogs, an increase in the percentage of lymphocytes, eosinophils, and neutrophils was detected. Sensitized dogs developed chronic interstitial inflammation with lymphocytes, macrophages, plasma cells, and eosinophils in lungs. Granulomas with lymphocytes, histiocytes, and giant cells were detected in both the interstitium and the bronchiolar wall in the lungs of sensitized dogs. PaO2 was lowest in dogs showing the most severe interstitial inflammation in the lungs. The results indicate that dogs can be successfully used in immunologic and physiologic studies of PS-induced HP.