MITE-INDUCED ALLERGIC AIRWAY INFLAMMATION IN GUINEA-PIGS

Background: Mites are the most common aeroallergen in human allergic a sthma. However, no animal model of mite-induced allergic airway inflam mation has been reported before. In this study, an animal model of mit e-induced allergic airway inflammation in guinea pigs was developed. M ethods: Firstly, we found that two intraperitoneal injections of 100 m u g crude mite extract (CME), but not multiple aerosol inhalations of 10 mg/ml CME, can cause sensitization in guinea pigs. The sensitizatio n to mites was confirmed by the measurement of serum antimite antibody titer and the detection of anaphylactic bronchoconstriction after int ravenous injection of CME solution. Then, single or multiple aerosol c hallenges with different concentrations (8, 4 or 1 mg/ml) of CME in th ese sensitized animals were performed. The total white cell and differ ential counts in the bronchoalveolar lavage (BAL) fluids were studied at different time intervals after challenge in different animals, and tracheal pathology was performed to detect the allergic airway inflamm ation. For comparison with the study in animals treated with CME, a BA L study in animals treated with ovalbumin was also performed. Results: The inhalation challenge of CME aerosol in sensitized animals caused prolonged eosinophilia in BAL fluid which persisted for at least 7 day s after single challenge. Neither inhalation challenge at higher conce ntrations of CME aerosol nor repeated inhalation challenges increased the degree of eosinophilia in BAL fluid compared to a single challenge . Using the same procedures, we also found that the mite model caused more eosinophilia in BAL fluid than did ovalbumin. Conclusion: This is the first report of an animal model of mite-induced allergic airway i nflammation in guinea pigs which can provide us with a useful model to study airway inflammation of mite-induced asthma in humans.