Methods: BALB/c mice were i.p. immunized with different doses of Der p lyophilized extract three times in three week interval in the mixture with Al(OH)3. 8 weeks after the final immunization mice were challenged with Der p during five consecutive days by intranasal applications (INA) or aerosol administration (AA). All mice were divided into 5 experimental groups: group 1 was immunized with 50 µg/mouse of Der p (in protein equivalent) in the mixture with 2 mg/mouse Al(OH)3 and challenged by INA; group 2 was immunized in the same way and challenged by AA; group 3 was immunized with 100 µg/mouse Der p in the mixture with 2 mg/mouse of Al(OH)3 and challenged by INA; group 4 was immunized in the same way and challenged by AA; group 5 (negative control) was immunized and challenged with saline. 24 hours after the last challenge airway hyperresponsiveness (AHR) to different concentrations of methacholine was evaluated in all groups by whole-body plethysmography. 48 hours after the last challenge in all groups blood was collected for differential cell count, brochoalveolar lavage fluid (BALF) was sampled for the determination of inflammatory cells and lungs were removed for histological analysis. Histopathological changes were graded according to semi-quantitative scoring system. Serum anti-Der p IgE, IgG1 and IgG2a antibodies were detected by ELISA seven days after the last immunization and 48 hours after the challenge.
Results: The highest level of serum Der p-specific IgE antibodies was observed in group 2. The levels of Der p-specific serum IgG1 and IgG2a antibodies in group 2 were significantly higher than that of other experimental groups. The maximum of AHR was observed in groups 1 and 3 challenged by INA. Analysis of cell composition in BALF demonstrated elevated number of basophils in group 3 in comparison with other experimental groups. No significant differences in peripheral blood cell counts were observed among experimental groups. Histological picture of allergic inflammation in lungs (peribronchial and perivascular infiltration with inflammatory cells) was the most expressive (according to score system) in group 3 in comparison with other experimental groups.
Conclusion: Data obtained indicate that sensitization with Der p in a dose 100 µg/mouse together with Al(OH)3 and challenge with Der p by INA is a suitable approach for modeling of mouse allergic asthma.