Influence of the Adjuvants and Genetic Background on the Asthma Model Using Recombinant Der f 2 in Mice

Der f 2 is the group 2 major allergen of a house dust mite (Dermatophagoides farinae) and its function has been recently suggested. To determine the optimal condition of sensitization to recombinant Der f 2 (rDer f 2) in murine model of asthma, we compared the effectiveness with different adjuvants in BALB/c and C57BL/6 mice. Mice from both strains sensitized with rDer f 2 by intraperitoneal injection or subcutaneous injection on days 1 and 14. The dosage was $20{\mu}g$. Freund's adjuvants with pertussis toxin (FP) or alum alone were used as adjuvants. On days 28, 29, and 30, mice were challenged intranasally with 0.1% rDer f 2. We evaluated airway hyperresponsivenss, eosinophil proportion in lung lavage, airway inflammation, and serum allergen specific antibody responses. Naive mice were used as controls. Airway hyperresponsiveness was increased in C57BL/6 with FP, and BALB/c with alum (PC200: $13.5{\pm}6.3$, $13.2{\pm}6.7$ vs. >50 mg/ml, p<0.05). The eosinophil proportion was increased in all groups; C57BL/6 with FP, BALB/c with FP, C57BL/6 with alum, BALB/c with alum ($24.8{\pm}3.6$, $20.3{\pm}10.3$, $11.0{\pm}6.9$, $5.7{\pm}2.8$, vs. $0.0{\pm}0.0$%, p<0.05). The serum allergen specific IgE levels were increased in C57BL/6 with FP or alum (OD: $0.8{\pm}1.4$, $1.1{\pm}0.8$, vs. $0.0{\pm}0.0$). C57BL/6 mice were better responders to rDer f 2 and as for adjuvants, Freund's adjuvant with pertussis toxin was better.