Respiratory allergy to Blomia tropicalis : Immune response in four syngeneic mouse strains and assessment of a low allergen-dose, short-term experimental model

Abstract

Doc number: 51

Abstract

Background: The dust mite Blomia tropicalis is an important source of aeroallergens in tropical areas. Although a mouse model for B. tropicalis extract (Bt E)-induced asthma has been described, no study comparing different mouse strains in this asthma model has been reported. The relevance and reproducibility of experimental animal models of allergy depends on the genetic background of the animal, the molecular composition of the allergen and the experimental protocol.

Objectives: This work had two objectives. The first was to study the anti-B. tropicalis allergic responses in different mouse strains using a short-term model of respiratory allergy to Bt E. This study included the comparison of the allergic responses elicited by Bt E with those elicited by ovalbumin in mice of the strain that responded better to Bt E sensitization. The second objective was to investigate whether the best responder mouse strain could be used in an experimental model of allergy employing relatively low Bt E doses.

Methods: Groups of mice of four different syngeneic strains were sensitized subcutaneously with 100 μg of Bt E on days 0 and 7 and challenged four times intranasally, at days 8, 10, 12, and 14, with 10 μg of Bt E. A/J mice, that were the best responders to Bt E sensitization, were used to compare the B. tropicalis -specific asthma experimental model with the conventional experimental model of ovalbumin (OVA)-specific asthma. A/J mice were also sensitized with a lower dose of Bt E.

Results: Mice of all strains had lung inflammatory-cell infiltration and increased levels of anti-Bt E IgE antibodies, but these responses were significantly more intense in A/J mice than in CBA/J, BALB/c or C57BL/6J mice. Immunization of A/J mice with Bt E induced a more intense airway eosinophil influx, higher levels of total IgE, similar airway hyperreactivity to methacholine but less intense mucous production, and lower levels of specific IgE, IgG1 and IgG2 antibodies than sensitization with OVA. Finally, immunization with a relatively low Bt E dose (10 μg per subcutaneous injection per mouse) was able to sensitize A/J mice, which were the best responders to high-dose Bt E immunization, for the development of allergy-associated immune and lung inflammatory responses.

Conclusions: The described short-term model of Bt E-induced allergic lung disease is reproducible in different syngeneic mouse strains, and mice of the A/J strain was the most responsive to it. In addition, it was shown that OVA and Bt E induce quantitatively different immune responses in A/J mice and that the experimental model can be set up with low amounts of Bt E.