OBJECTIVETo examine the levels of nerve growth factor (NGF) and interleukin-4 (IL-4) in the induced sputum of children with cough variant asthma (CVA), with the aim of studying the roles of NGF and IL-4 in childhood CVA.

METHODSThirty-four children with CVA were enrolled in this study. Twenty healthy children were used as a normal control group. The induced sputum was separated into supernatant and cells. Hematoxylin and eosin staining was used to count differential cells. The expression of NGF and IL-4 in supernatant was measured using ELISA. The mRNA expression of NGF and IL-4 in cells was determined by Real-time PCR analysis.

RESULTSThe percentage of eosinophils in the CVA group was significantly higher than in the control group [(13.4±3.6)% vs (2.6±1.7)%; P<0.01]. The expression of NGF and IL-4 protein and mRNA in induced sputum was significantly higher in the CVA group than in the control group (P<0.05). The expression of NGF and IL-4 protein and mRNA was positively correlated with the percentage of eosinophils (P<0.01). The expression of NGF and IL-4 protein and mRNA in induced sputum was significantly reduced in the CVA group after treatment (P<0.05).

CONCLUSIONSEosinophils infiltration and increased expression of NGF and IL-4 play key roles in the development of childhood CVA, suggesting that they may be useful in the diagnosis and treatment of childhood CVA.