Increase in serum IgE levels of ovalbumin-sensitized cats and the detection of elastase and collagenase activities in secretions of sensitized feline alveolar macrophages challenged in vitro.

The feline model of respiratory hypersensitivity induced by intraperitoneal injection of ovalbumin has been studied. IgE serum antibodies were present for 3-10 weeks following sensitization, with maximum titers occurring between 50 and 70 days. Similarly, peak passive cutaneous anaphylaxis reactions occurred between 50 and 70 days. Alveolar macrophages, obtained by tracheal lavage at 65 days after sensitization, produced elastase like and collagenase-like secretions 48 h after challenge with ovalbumin in culture. Macrophages from nonsensitized cats did not produce these secretions. It is hypothesized that reaginic antibodies and sensitized alveolar macrophages, such as those found in the cat model, may be responsible in part for the destruction of lung tissue found in long-term respiratory diseases, similar to fibrosing alveolitis and pulmonary emphysema in man.