[Experimental study on recombinant Bla g 2(rBla g 2) in the treatment of allergic asthma in mice]

To study the therapeutic effect on murine allergic asthma with recombinant Bla g 2 (rBla g 2) allergen and its possible mechanism.

Eighteen BALB/C mice were randomly divided into three groups: normal control group (group A), asthma model group (group B), and recombinant protein rBlag2 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.

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) x 10(5)/ml] and eosinophils [(22.20 +/- 3.76) x 10(5)/ml] in BALF of group B significantly increased than those of group C [(14.30 +/- 4.95) x 10(5)/ml and (5.20 +/- 1.56) x 10(5)/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 inflammation of group C reduced considerably. Each test value of group C was substantially similar to that of group A.

The experiment shows proper immunotherapeutic efficacy of rBla g 2 in murine allergic asthma, which may possibly related to the apoptosis of eosinophils.