摘要Objective To evaluate the role of interleukin-5 (IL-5) in the pathogenesis of allergic asthma, we observed the effects of recombinant human (rh) IL-5 inhalation on changes of activity and number of circulating eosinophils in allergic asthmatics, as well as concentrations of serum IgE.Methods A randomized double-blind, placebo-controlled study design was employed in each subject which acted as his or her own control. Eight nonsmoking asthmatics were enrolled in this study. All paients had mild atopic asthma, with baseline forced expiratory volume in 1 second (FEV1) greater than 70% of predicted value, requiring only intermittent use inhaled β2-agonists. Each paitent had one or more documented positive skin prick test responses to aeroallergens. None had received inhaled or oral corticoseroids in the previous 3 months. Each subject inhaled 10 μg of rhIL-5 (Genzyme Co., Boston, MA) in vehicle (0.1% bovine serum albumin in 0.9% saline) or vehicle only as a 0.5 ml nebulized solution. At least 4 weeks were allowed to elapse between the two inhalation, and the order of inhalation of rhIL-5 or vehicle was randomized. Measurements of total nuclear blood cell counts and cell differntial counts, and concentrations of eosinophil cationic protein (ECP) were performed before, and at 2, 24, and 48 h after the inhalation of rhIL-5 or vehicle. Levels of ECP in serum were determined with commercially available ECP Fluoroimmunoassay kits (Pharmacia AB, Uppsals, Sweden) according to the procedures recommended by the manufactures. All data were presented as mean±standard error of mean. Statistical analysis was done by repeated measures analysis of variance (ANOVA) for data conforming to a normal distribution, and by Friedman's test for those data with a nonparametric distribution.Results Eosinophil numbers and ECP levels within the control group did not appear to change from baseline at any time throughout the study. Eosinophil numbers from baseline (3.6±1.1×105/ml) to 6.3±1.2×105/ml (P<0.01) at 24 h, and to 5.7±0.9×105/ml (P<0.01) at 48 h after IL-5 inhalation. Accompanying this significant blood eosinophilia was a significant elevation of serum ECP levels. Compared with baseline value (6.3±1.1 pg/ml), inhalation of IL-5 lead to ECP levels in crease with time, reaching a significant hight extent at 24 h (17.6±2.8 pg/ml, P<0.01); And this elevated ECP levels lasted at least 48 h (18.1±2.9 pg/ml, P<0.01). However, IL-5 inhalation had no significant effect of levels of serum total IgE.Conclusions The findings in the present study provided direct evidence the IL-5 not only induced a significant blood eosinophilia, but also resulted in the activation of circulating eosinophils. Our data further support the importance of IL-5 in the pathogenesis of brochial asthma in human.