Effects of oral hyposensitization with recombinant Der f2 on immediate airway constriction in a murine allergic model

Recombinant Der f2 (rDer f2) has recently been developed as a promising allergen for the diagnosis and immunotherapy of house-dust mite allergy, and studies in immunology. The aim of the present study was to evaluate whether oral administration of rDer f2 could suppress an immediate allergic reaction in mice sensitized with mite allergen. We developed a murine allergic model that showed bronchoconstriction after inhalation of rDer f2, and studied the effect of oral administration of rDer f2 on the reaction. Seven week old male A/J mice were intranasally immunized with rDer f2 12 times. Sensitized mice showed anti-rDer f2 immunoglobulin (Ig)E production and immediate airway constriction after inhalation of 10 mg.mL(-1) of rDer f2, as determined by the Konzett-Rossler method. Immunized animals were divided into three groups, and fed phosphate-buffered saline (PBS), 0.1 mg.day(-1), or 1 mg.day(-1) of rDer f2 for 4 weeks, respectively. Seven days after the last feeding, the mice were examined for their immediate response. Animals fed with 1 mg.day(-1) rDer f2 showed significantly reduced bronchoconstriction after inhalation of both 2 mg.mL(-1) and 10 mg.mL(-1) of rDer f2 compared with PBS-fed mice. Similar results were obtained when we examined mice 10 weeks after the last feeding. Reactions in the 0.1 mg.day(-1) rDer f2-fed group also tended to decrease in comparison with PBS-fed animals. Plasma anti-rDer f2 IgE, IgG1, IgG2a, and IgG2b levels were not changed by feeding with rDer f2. We conclude that recombinant Der f2 exhibits both sensitizing and hyposensitizing activities in mice. rDer f2 may be useful in immunotherapy and diagnosis of house-dust mite allergy.