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-Rössler 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 housedust mite allergy. Eur Respir J 1998; 11: 144-150 To date, several clinically important allergens such as Der 1 and Der 2 have been identified in crude mite extract [1][2][3][4]. Among others, the structural gene of Der f2, one of the major mite allergens found in Dermatophagoides farinae was cloned, and the product (recombinant Der f2 (rDer f2)) shown to exhibit allergic activity in humans comparable with native Der f2 prepared from crude mite extract [5,6]. Since Der f2 has been shown to sensitize over 80% of patients with house-dust mite allergy, rDer f2 should prove useful in the diagnosis and immunotherapy of allergic asthma and rhinitis caused by house-dust mites. It should also provide a basis for research into allergies and immunology.In the present study, with special reference to the therapeutic application of rDer f2, we established a murine allergic model by intranasal or intraperitoneal injection of rDer f2 to A/J mice, which are highly responsive to Der f2 [7]. We examined the effect of oral-hyposensitization therapy with rDer f2 against the immediate bronchoconstriction in the intranasally sensitized animals because their reaction after rDer f2 inhalation was more intense than that of intraperitoneally immunized mice.
Materials and methodsAntigen rDer f2, clone 1 [5], was kindly supplied by the Nikka Whisky Distilling Co., Ltd. (Chiba, Japan), and dissolved in...