Abstract: Objective To study the therapeutic effect on murine allergic asthma with recombinant Bla g 2 （rBla g 2）allergen and its possible mechanism. Methods Eighteen BALB/C mice were randomly divided into three groups: normal control group（group A）, asthma model group（group B）, and recombinant protein rBla g 2 treatment group（group C）. Mice in groups B and C were subcutaneously immunized weekly with rBla g 2（50 mg）formulated in Al（OH）3 adjuvant for three weeks. Group A received only adjuvant emulsified with normal saline. Two weeks after the last inoculation, mice in group C were administered each with rBla g 2（100 mg）/dose, and groups A and B were given PBS. All the mice received eight doses at 2-day intervals. One week after the last immunotherapy, mice in groups B and C were intranasally challenged with 50 mg rBla g 2 daily for seven days, while mice in group A received PBS. Twenty-four hours after the challenge, the following items were examined: airway hyperresponsiveness of mice, total cellular score and cell classification in bronchoalveolar lavage fluid（BALF）, level of rBla g 2-specific IgE and IgG2a in serum, lung inflammation by HE stain, and Bcl-2 expression of eosinophils of lung by immunohistochemistry. Results Compared with group B, group C showed a decreased Penh value of airway hyperresponsiveness（P＜0.05）, reduced serum rBla g 2-specific IgE but increased IgG2a（P＜0.01）, and reduced Bcl-2 expression of eosinophils. Total cells［（24.60±15.08）×105/ml］and eosinophils［（22.20±3.76）×105/ml］ in BALF of group B significantly increased than those of group C［（14.30±4.95）×105/ml and（5.20±1.56）×105/ml，respectively］（P＜0.01）. The interstitial space surrounding the airway lumen was characterized by a denseｌｙ mixed cellular infiltrate, tissue edema and epithelium tissue damage in group B, while lung inflamma-tion of group C reduced considerably. Each test value of group C was substantially similar to that of group A. Conclu-sion The experiment shows proper immunotherapeutic efficacy of rBla g 2 in murine allergic asthma, which may possi-bly related to the apoptosis of eosinophils.

Key words: Blatella germanica, Recombinant Bla g 2（rBla g 2）, Asthma, Eosinophil, Bcl-2