Objective To investigate the expression of RNP（alpha defensins） in guinea pigs with bronchial asthma and the influences of P2Y2 receptors on the expression. Methods Seventy-two adult male guinea pigs were randomly divided into a control group （group A） and an asthma group （group B）. The asthma model was established by sensitizing with ovalbumin injection intraperitoneally and challenging with ovalbumin inhalation. Then the A and B groups were divided into following subgroups,ie,the saline groups （A1/B1），ATP groups （A2/B2），and Suramin groups （A3/B3），in which the animals were intervented with saline，ATP，and suramin respectively. Total pulmonary resistance （RL） was measured.Total and differential cell counts in bronchoalveolar lavage fluid （BALF） were measured. Pathological changes of lung were observed under light microscope using HE staining. The plasma levels of RNP and IL-8 were measured by ELISA. The protein and mRNA expressions of RNP and P2Y2 were detected by immunohistochemistry and RT-PCR. Results The RL increased significantly as much as 10% in group B compared with group A. Pathological study revealed that luminal narrowing of bronchus and inflammatory cells infiltration in the asthma group. The total cell and polymorphonuclear neutrophil （PMN） counts in BALF in group B1 were significantly higher than group A1 and B3，but lower than group B2 （Plt;0.05）,but no significant difference among group A1，A2，or A3 was found. The RNP expression in plasma and lung tissue in group B1 was higher than group A1 and B3，but lower than group B2 （Plt;0.05）. The RNP expression in plasma and lung tissue was lower in group A1 than group A2，but higher than group A3（Plt;0.05）. The IL-8 expression in plasma in group B1 was significantly higher than group A and B3，but lower than group B2 （Plt;0.05） but no significant difference among group A1，A2，or A3 was found（Pgt;0.05）. RNP protein expressed predominantly in lung tissues，especially where the PMN infiltrated. The expression of RNP mRNA were consistent with the RNP protein expression in all groups. P2Y2 mRNA expression in group A1 was lower than group A2，and higher than group A3 （Plt;0.05）.P2Y2 mRNA expression in group B1 was lower than group B2 but higher than group B3 （Plt;0.05）. The linear correlation analysis showed that RNP had no significant correlation with PMN and IL-8 in group A，and was positively correlated with P2Y2 mRNA （Plt;0.05） while RNP was positively correlated with PMN，IL-8，and P2Y2 mRNA in group B. Conclusion RNP expression increases in bronchial asthma guinea pigs and may be related to P2Y2 receptors.