Abstract: 【Abstract】   Objective   To explore the efficacy of intranasal treatment by immunosuppressant tacrolimus for allergic asthma and its mechanism in mice.  Methods  24 female BALB/c mice were randomly divided into 4 groups: group A （negative control）， group B （model control）， group C （low dose treatment）， and group D （high dose treatment）. Mice in group A were treated with saline （100 μl）. Other groups were sensitized intraperitoneally with allergen extracts of Dermatophagoides farinae （Der f） absorbed to Al（OH）3 at day 0， 7， and 14. From day 28， groups A， B， C， and D were intranasally treated with saline， PBS， 0.01% tacrolimus， and 0.1% tacrolimus， respectively， once per day for 7 d， and followed by intranasal challenge with 50 μl Der f extracts in the mean time. 24 h after the last challenge， the airway hyper-responsiveness （AHR） were detected. At 48 h after the last challenge, the mice were sacrificed, the bronchoalveolar lavage fluid （BALF） was collected, the lungs and spleen were aseptically removed. The total cell number and cell classification of BALF were recorded. The level of interleukin-4 （IL-4）， interleukin-5 （IL-5）， interferon-γ （IFN-γ） in BALF and in spleen cells culture supernatants was detected by ELISA. The lung inflammation and mucus secretion were observed in mice by HE （haematoxylin and eosin） staining and AB （Alcian Blue） staining.  Results  Compared with group B， AHR （P<0.05） and airway inflammation in group D significantly reduced. The number of total cells ［（29.92±5.20）×104/ml］ （P＜0.05） and eosinophils ［（4.33±0.75）×104/ml］ （P＜0.01） in group D greatly decreased than those of group B ［（59.33±5.99）×104/ml and （22.67±5.65）×104/ml］. The level of IL-4 ［（22.49±4.96） pg/ml］ （P＜0.05）, IL-5 [（43.90±13.15） pg/ml］ （P＜0.01） and IFN-γ ［（10.17±1.09） pg/ml］ （P＜0.05） in BALF significantly decreased （P<0.05） than those of group B ［（57.02±7.38）， （133.49±15.63） and （15.32±3.23） pg/ml, respectively］. The level of IL-4 ［（22.54±4.58） pg/ml］， IL-5 ［（36.31±20.85） pg/ml］ and IFN-γ ［（11.28±1.79） pg/ml］ in spleen cell culture supernatant all sig-nificantly decreased （P<0.05） than those of group B ［（56.34±6.21）， （72.32±6.23） and （18.82±1.88） pg/ml, respectively］. There was no significant difference between group C and group B.  Conclusion  Tacrolimus shows certain immune therapeu-tic effect on dust mite sensitized mice， and this effect may be attributed to its inhibition on T lymphocyte factor secretion.

Key words: Tacrolimus, Mice, Intranasal treatment, Asthma model, Dermatophagoides farinae