Abstract: AIM: To observe the effect of dexam-ethasone on the expression of neutrophil-activating pep-tide-2 (NAP-2)in neutrophil and explore the role of neutrophil in asthma rat .METHODS: In this experi-ment , the model rats of asthma were randomly divided into three groups on average, including asthma group, control group and dexamethasone treated group.Blood neutrophil were isolated and purified,the expression of NAP-2 protein in bronchial wall and in blood neutro-phil was detected by immunohistochemical assay .RESULTS: The expression of NAP-2 protein in blood neu-trophil from asthma group (0.198 ±0.016, optical density)was significant higher than that from control group (0.079 ±0.015, optical density)(P<0.01). And the expression of NAP-2 protein in blood neutro-phil from dexamethasone treated group (0.135 ± 0.021, optical density)was lower than that from asth-ma group, but was higher than that from control group (all P<0.01).While in bronchial wall , the expression of NAP-2 protein in asthma group (0.226 ±0. 050, optical density)was significant higher than that in control group (0.140±0 .012, optical density)(P<0.01).And the expression of NAP-2 protein in dex-amethasone treated group (0.175 ±0.028, optical density)was lower than that in asthma group, but was higher than that in control group (P<0.01).There were significant positive correlation between NAP-2 protein expression in blood neutrophil and the number of NEU in bronchoalveolar lavage fluid(n =29, r = 0.334, P<0.05).CONCLUSION: The levels of NAP-2 protein in blood neutrophil were increased in rat asthma .Neutrophil may be involved in asthma inflam-mation via NAP-2.The decreased inflammation of asth-ma by dexamethasone may partly depend on suppressing the synthesis of NAP-2 protein, which may be correlat-ed with the influx of neutrophil into lung tissue .

Key words: asthma, neutrophil-activating peptide-2, immunohistochemical method, neutrophil, dexamethasone