Allergen-Induced Airway Inflammation Related to Sensitization and Provocation Doses in Rat

Park, Seog Chea; Choi, In Seon; Koh, Young Il; Jang, An Soo; Lee, Shin Seok; Kang, Kwang Won

Abstract

It has been reported that an exposure to allergen aerosol induces airway inflammation in sensitized animals. The aims of this study were to characterize allergen-induced airway inflammation, and to determine the most appropriate sensitization and provocation doses to induce airway inflammation in rats. Eighty-three male Sprague-Dawley rats were actively sensitized with a subcu- taneous injection of 0, 10, or 1000microg ovalbumin (OA) and 14 days later they were provoked with 0, 1, or 5% OA aerosols. One day after the provocation, the levels of OA-specific IgE in serum, cell numbers in bronchoalveolar lavage (BAL) fluid were measured. The results were as follows; 1. Early asthmatic responses (EAR) were observed in 54.0% in OA-sensitized/ OA-provoked rats. 2. The levels of serum OA-specific IgE in OA-sensitized rats were significantly higher than those in nonsensitized rats(89.2+/-1.8x10-3OD vs 81.0+/-1.7x10-3OD, p<0.01). 3. There were significant increases in the number of total cell, neutrophils, lymphocytes and eosinophils in BAL fluid obtained from OA-sensitized /OA-provoked rats compared to control rats. 4. The levels of OA-specific IgE in serum related with eosinophil counts in BAL fluid obtained from OA-sensitized/saline-provoked rats, and related with neutrophil counts in BAL fluid from OA-sensitized/OA-provoked rats. 5. The numbers of BAL fluid eosinophils were significantly higher in 1000microg OA-sensitized rats than in 10microg OA-sensitized rats, and the numbers of eosinophils and neutrophils in 5% OA-provoked rats than in 1% OA-provoked rats. In conclusion, provocation with OA aerosols developed EAR and increases in BAL fluid inflammatory cells. The numbers of inflammatory cells in BAL fluid depended on serum OA-specific IgE level, sensitization and provocation doses. EAR tended to be developed well in low (10microg) sensitization and high (5%) provocation doses, but airway inflammation on high (1000microg) sensitization and high (5%) provocation doses of OA in rats.